# 1989 d21 SE ecu trouble.



## BSERIES18C407 (Mar 17, 2020)

Sup people's new to forum/ Nissan's so kinda learning how they work, got a 89 SE 5spd bought with tired motor so swapped in a 2000 xterra/pathfinder vg33e not sure which one but has always been in limp mode from day one code 51 after purchasing injector,dist,ecu with no luck, understand the injector/tbi operation but couldn't find anything wrong injector circuit,so just went and installed 33 motor and swapped all sensors/eng harness over, it ran but with same issue unfortunately it took a drive in it too find out problem remains but this time had to pull back home after analysing everything i found my fuel pump isnt priming or injectors aren't spraying well after many many many weekends spent up stupid late tryin to figure this shit out before i blow a gasket and put a stick of dynamite under the gas tank this my last chance of ever getting this thing running have owned it 3yrs know and drove it maybe 4 times, (so ashamed of myself ) !! But i dont quit easy and could've long time ago but to prove everyone i know wrong about it being worth the trouble i want this thing to run like it should be with the record of dependability they're known for hell wouldn't mind getting the late 80's single turbo manifolds and boost it being most my friends got full size chevy and fords lol but like to be different rather than follower any help greatly appreciated fella's.


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## jp2code (Jun 2, 2011)

Unplug the injectors, one by one, and see which one doesn't cause a worse condition. Replace that one.


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## BSERIES18C407 (Mar 17, 2020)

jp2code said:


> Unplug the injectors, one by one, and see which one doesn't cause a worse condition. Replace that one.


Its a tbi setup original engine was vg30i so there's only 2 injectors but aside from that ecu isnt powering up upon ignition being turned on so injectors isnt firing fuel pump isnt priming but if i unplug i believe furthest plug to the right if on passenger side looking at ecu service manual says to attach pin#6 blu/red wire to a ground to check something else but when i do that ecu will come on but unfortunately the plug isnt isnt pluged in with remaining other wires that are in it. Why has this been such a nightmare smh thanks for pointer though appreciate reading my issue.


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## rogoman (Dec 16, 2004)

There's a fusible link that may have blown. Check for 12v at the safety relay. Here are two pictures:







:


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## jp2code (Jun 2, 2011)

After checking the fusible links, check the fuses to see if the one going to the ECU is good. The ECU controls when the injectors fire. If it doesn't work, your engine will not crank. If you are not going to use the ECU, you will need to do a Weber carburetor swap.


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## BSERIES18C407 (Mar 17, 2020)

Man i think tried so many different things i cant even think of what im doin anymore, ive got the fsm and did everything it says and yet the problem is still current, i just figured out if i jump 2 pins on main relay with it unplugged ecu will come on fuel pump still not priming but ecu works so i did the main relay procedures and all checked out ohmed the relay itself and again checked out so it seems somehow there's a grounding issue in regards to ecu/relay not working but it would lead me to think something with my key ignition switch possibly? Is this a possibility maybe im not one to give up especially when its my money dumped into it but im on my knees just about and sometimes wanting to light a stick of dynamite under this nightmare, until i catch some air along with a break from it , and the carburetor was a thought but its not practical enough as far as weather changes but was thinking hard about it sorry for long reply just beem trying everything possible so appreciated you guys getting back at me with help.


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## BSERIES18C407 (Mar 17, 2020)

rogoman said:


> There's a fusible link that may have blown. Check for 12v at the safety relay. Here are two pictures:
> View attachment 6343
> :
> 
> View attachment 6342


Tried this and to my knowledge everything checked out,but safety switch this is what i did to figure out 51 code truck has had from day one with original engine in place.


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## BSERIES18C407 (Mar 17, 2020)

Will look into safety switch though and let you guys know what results are.


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## jp2code (Jun 2, 2011)

I have heard a lot of owners talk about the ignition switch going out. It would seem odd that it's failure would coincide with your engine swap. Possible though.


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## BSERIES18C407 (Mar 17, 2020)

Ive heard similar things something about ģround signaling,but aside from this as luck would have it, i was about to wrap up for the night and due to my devotion to figuring out why ecu wont come on i decided to try one i bought at the time i was trying to figure out the infamous code51 which at present time the legend continues on to the jdm vg33e currently in truck, to plug ecu in and see if same results occur, and wouldn't you know dame thing comes on, smh so some where along this nightmare the original ecu got burnt or something, which strange being everything thing ive tried has been from the fsm but that's good news and a progress, unfortunately no good story ends with a victory, dam fuel pump still isnt priming and ohmed relay checks out, checked voltage supply at relay inputs also checks out so what am i missing fellas? Also code 51 haunts over truck still which at point of converting to mpfi more efficiency and power from engine made when all problems are fixed of course any ideas to why relay isnt doing its job for fuel pump ? (Yes fuel pump works and yes fuses are good) so thats crossed out any help greatly appreciated guys.


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## rogoman (Dec 16, 2004)

BSERIES18C407 said:


> Ive heard similar things something about ģround signaling,but aside from this as luck would have it, i was about to wrap up for the night and due to my devotion to figuring out why ecu wont come on i decided to try one i bought at the time i was trying to figure out the infamous code51 which at present time the legend continues on to the jdm vg33e currently in truck, to plug ecu in and see if same results occur, and wouldn't you know dame thing comes on, smh so some where along this nightmare the original ecu got burnt or something, which strange being everything thing ive tried has been from the fsm but that's good news and a progress, unfortunately no good story ends with a victory, dam fuel pump still isnt priming and ohmed relay checks out, checked voltage supply at relay inputs also checks out so what am i missing fellas? Also code 51 haunts over truck still which at point of converting to mpfi more efficiency and power from engine made when all problems are fixed of course any ideas to why relay isnt doing its job for fuel pump ? (Yes fuel pump works and yes fuses are good) so thats crossed out any help greatly appreciated guys.


You just said that when you replaced the ECU, the truck started up. In that case the fuel pump is working. So what is the actual problem at this point?


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## jp2code (Jun 2, 2011)

Relays go out. Try putting 12V across the terminals and see if the relay clicks on.


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## BSERIES18C407 (Mar 17, 2020)

rogoman said:


> You just said that when you replaced the ECU, the truck started up. In that case the fuel pump is working. So what is the actual problem at this point?


Quote= ECU COMES ON DOESN'T SAY ENGINE IS RUNNING OF WHICH WAS NEVER STATED,however i will repeat again incase someone else is confused for some odd reason, was having issues with fuel pump priming initially upon diagnosing this problem somewhere along the the ecu suddenly stopped working (dont know how this happened or exactly when because was focused on relay's and fuse links etc. After realizing that started checking why it didn't come on (power,grounds, what fsm procedures called) then before was finished for the night i looked at another ecu i bought when original engine was in truck and having code 51 problem which after ecu,distributor and new injector bought still continues on with current engine but is reason for having second computer to have and plug in ?


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## BSERIES18C407 (Mar 17, 2020)

jp2code said:


> Relays go out. Try putting 12V across the terminals and see if the relay clicks on.


Ok so basically add 12v to the relay itself to verify it makes click sound, ok cool will let guys know results just at moment i got truck at a storage facility cause HOA doesn't allow mechanic work and when installing engine was only choice bur know this Coronavirus bull shit limits time to do alot married with 3 teenagers so hard to disappear for some automotive session's smh but will check out and thanks again for the help.😏


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## jp2code (Jun 2, 2011)

BSERIES18C407 said:


> After realizing that started checking why it didn't come on (power,grounds, what fsm procedures called) then before was finished for the night i looked at another ecu i bought when original engine was in truck and having code 51 problem which after ecu,distributor and new injector bought still continues on with current engine but is reason for having second computer to have and plug in ?


I think you might have a slew of issues going on, and it sounds like you kept making unrelated changes when you had issues, and now your system is all fuked up.

So with the VG33e engine, did you use your existing throttle body injection system or are you trying to get the VG33e engine's multiport injection system to work in your 1989 truck?

When you mention the multiple ECUs, which 2 do you have?


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## BSERIES18C407 (Mar 17, 2020)

jp2code said:


> I think you might have a slew of issues going on, and it sounds like you kept making unrelated changes when you had issues, and now your system is all fuked up.
> 
> So with the VG33e engine, did you use your existing throttle body injection system or are you trying to get the VG33e engine's multiport injection system to work in your 1989 truck?
> 
> When you mention the multiple ECUs, which 2 do you have?


 Lol it probably would seem this way if reading this essay of things done but very mechanically inclined and have done more swaps than i got fingers unfortunately these are hondas and a friends f150 which helped him install a 351 out of a ski natique boat, but have no actual experience with Nissan's even though have decent amount of knowledge of the stupid fast jdm engines sr16/20vet,rb25,26det etc. But as for what i used for swap is basically everything from the original engine only head,block and front accessories- pwsteering,ac and alternator everything else is original from truck but has thousands of grounds from what i can see and being 1989 it shows it ive gone threw as many as i can find cleaning surface and cleaning copper surfaces but its the little things that those familiar with these trucks common issues that need to be addressed and its these things that im trying to address


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## jp2code (Jun 2, 2011)

If the Nissan Hardbody has a code stored in the ECU, the trucks will run in limp mode until the codes are fixed.


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## BSERIES18C407 (Mar 17, 2020)

Wow its been for ever it seems !! Sorry so long but did some testing on that relay buisness and fuel and main check out fine and at this point 2nd computer is working fuel pump is priming when ignition switch is turned on, and if squirt some fuel into throttle body motor fires up immediately until fuel is burned and then quits. So injectors arent firing but are getting 12v and obviously getting spark since fires up if fuel is added so now its its something the computer isnt receiving like signal or something also my tachometer barely moves whenever attempting to start it without adding fuel. It should clearly be moving whenever engine is cranking correct?


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## BSERIES18C407 (Mar 17, 2020)

Oh and as for question about engine codes i cant get it to run so not sure if there could be a code generated could it ? But the only code ive ever gotten is 51 and well before with old motor it would start without a problem just wouldn't rev past 2800. So this problem is still around but been told it could be oxygen sensors and coolant sensor thats causing the ecu to see something it doesn't like so it enters limp mode just cant do anything if wont even start and run so im in the dark on the injector circuit crap, anything that can help with mystery truck would be greatly appreciated guys.


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## jp2code (Jun 2, 2011)

The injectors could be blown or shorted. When you apply 12vdc to an injector, you should hear it click as the coil inside it is energized and the injector opens. It should click again after you remove power and it closes.

Also check the resistance between the terminals. The newer injectors expect 12 to 14 Ohms, but I think that the older ones like you have should be around 6 Ohms.


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## rogoman (Dec 16, 2004)

BSERIES18C407 said:


> Oh and as for question about engine codes i cant get it to run so not sure if there could be a code generated could it ? But the only code ive ever gotten is 51 and well before with old motor it would start without a problem just wouldn't rev past 2800. So this problem is still around but been told it could be oxygen sensors and coolant sensor thats causing the ecu to see something it doesn't like so it enters limp mode just cant do anything if wont even start and run so im in the dark on the injector circuit crap, anything that can help with mystery truck would be greatly appreciated guys.


The code 51 is for the Injector circuit as you know. Basically what is going on is that the ECM is picking up a signal from the O2 sensor, that a particular "pulse" is either running rich or lean. Now, there can be several causes of this. First, the obvious. That's a leaking injector. To find if you do have a leaking injector, I would pick up a fuel pressure test kit. This will "T" into the fuel line just after the fuel filter. Turn the key on, then off, and watch the fuel pressure. It should hold around 43psi for quite some time. If it drops off quickly, you probably have an injector sticking open.

Next, I would pull the plugs and inspect them one at a time. A plug that has raw fuel on it can be caused by a leaking fuel injector. There may also be carbon buildup on the plug due to an overly rich mixture or a weak spark. At this time, its also good to make sure the rest of your ignition system is operating properly (plugs, wires, cap & rotor). Any problems with those may cause misfires, possibly creating your code. Now, there are other factors that may also cause this problem. Those could be the O2 sensor itself, Air Flow Meter, EGR valve, timing, vacuum leaks, the ECM. Also check the harness connector at the injector.


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## BSERIES18C407 (Mar 17, 2020)

Ok that all makes sense , infact couple of those things to do's have been done in trying to pin point the cause, as for the oxygen sensor sending a signal its weird for that to be possible if injector/injectors arent working enough with given amount of time to have engine run rich but anything possible with these kind of problems but what i have just found out being code 51 is to do with circuitry is that if i unplug negative terminal from battery and attach test light clip to neg. terminal and touch ground post it lights up, and won't go out unless i disconnect black wire with male plugs on both ends within fuseable links otherwise no fuse or plug will put it out so know im understanding why there's no neg switching from ecu to injectors to fire them so i poured some 2stroke gas down card to get truck to run,lubricate cylinders and retrieve and possible eng codes thats could help identify the main problem and still only code 51. Thats where im at today will try to ohm and continuity test with fuseable links and let guys know thanks again for info to help me figure this out .


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## Ascotty (Apr 28, 2020)

It gave code 41 but not sure what it was


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## jp2code (Jun 2, 2011)

41 Intake Air Temperature Sensor

Do you know where the air temperature sensor is on your engine?


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## Ascotty (Apr 28, 2020)

I do not but I'm looking things up as I go I also found a female plug end on my fuel filter bracket that's not connected any idea what it could be.


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## jp2code (Jun 2, 2011)

It's that part in the lower left picture


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## jp2code (Jun 2, 2011)

The female plug end by the fuel filter bracket sounds like the O2 sensor plug. You will certainly be in limp mode if the O2 sensor isn't working properly.


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## BSERIES18C407 (Mar 17, 2020)

Yea mine was double checked when swapping the motor to a 33 its obvious something that i retained from original engine which is harness,int man,tbi and exhaust manifolds. Ohmed check injectors ohmed checked ground side switch for injectors as well as continuity for extra certainty and this dam truck refuses to get any better, no matter what money,time and patience you throw at it !!! still maintains least a problem or two doesn't seem like it wants to be fixed i swear !!!!! Omg want blow this [email protected]#$in thing up !!!!!


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## BSERIES18C407 (Mar 17, 2020)

You know its getting bad when a giant peace of metal has ability to almost have u on knees cryin with rage and tear of frustration be encropitive!!!!!!!!


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## jp2code (Jun 2, 2011)

Have you checked the ignition timing?

Do you know if the VG33E was working properly when you got it? If the timing belt slipped or is off, codes won't solve anything.


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## rogoman (Dec 16, 2004)

BSERIES18C407 said:


> Yea mine was double checked when swapping the motor to a 33 its obvious something that i retained from original engine which is harness,int man,tbi and exhaust manifolds. Ohmed check injectors ohmed checked ground side switch for injectors as well as continuity for extra certainty and this dam truck refuses to get any better, no matter what money,time and patience you throw at it !!! still maintains least a problem or two doesn't seem like it wants to be fixed i swear !!!!! Omg want blow this [email protected]#$in thing up !!!!!


From my experience, it's never a good idea to perform a continuity check on the signal wire of an injector. With the ohmmeter, you're introducing a voltage into the ECU; there's a possibility of damaging the ECU. The signal wire does not go to direct ground, instead it goes to the ECU. The ECU provides a temporary ground in order to fire the injector at that moment. The safest method to determine if the signal wire is operating is to use a "noid light" kit; you would unplug the injector harness connector and plug the "noid light" harness connector in series with the circuit; you would do this for each injector.


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## BSERIES18C407 (Mar 17, 2020)

Your right which is why its best to unplug both ends before doing continuity test therefore no damage is applied to ecu, and yes motor has nothing wrong with it in fact moment i put any fuel down tbi it fires up immediately until burns fuel up and quits have fuel pressure up to throttle body injectors not pulsing,tryin to test circuit but fsm procedures show test when engine is running and that is kinda hard to do at the moment is it possible for crank sensor to be faulty but still deliver spark signal? Also both injector ohmed at 2.5-2.6 ohms and im finding they should be at 1.5 ohms so if there's any one can verify this of there's so i know for sure this isn't good there not cheap at all and thinking about just converting this nightmare to mpfi if i can source donor truck/car to get parts.


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## jp2code (Jun 2, 2011)

Post this issue on Infamous Nissan. There are some good members here, but there are more there. Maybe someone can figure out your issues. 

Seems like you are not getting fuel. Fusible links can burn out making injectors stop working. Fuel filter can get clogged. Fuel line could have gotten crushed during the engine swap. If all that is good, I'd say replace the injectors with new or rebuilt ones or just throw a Weber carburetor kit on it.


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## BSERIES18C407 (Mar 17, 2020)

Yes i swore i already replied to that already but yes its not good to do a continuity test with pluged into ecu but knowing this i did test after unplugged from ecu but good that you're advising that some would naturally make that mistake, but good news as off now and im still slapping myself on back of the head the problem came down to the one of the very first things that already known to check first and thats constant fuel pressure i checked some what orginally but that was fuel already in filter and line but when i disconnected fuel filter and turned key on pump primes but aint a drop of fuel coming out, and primed it few times as well as cranked over and nothing is coming out even turned fuel pump on manually from relay inputs and with pump whirring away nothing comes out so guessing there's another filter underneath bed or by tank but thats a tomorrow show finished for tonight update tomorrow with finding. Lmk if there's anything to be aware of with this scenario.


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## BSERIES18C407 (Mar 17, 2020)

Dam page wasn't updated lol know i see the new replies my mistake 😒


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## jp2code (Jun 2, 2011)

Nissan doesn't have another fuel filter besides the one in the engine compartment. 

It sounds like the fuel line is clogged or the steel line got crushed shut.


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## BSERIES18C407 (Mar 17, 2020)

Yes i swore i already replied to that already but yes its not good to do a continuity test with pluged into ecu but knowing this i did test after unplugged from ecu but good that you're advising that some would naturally make that mistake, but good news as off now and im still slapping myself on back of the head the problem came down to the one of the very first things that already known to check first and thats constant fuel pressure i checked some what orginally but that was fuel already in filter and line but when i disconnected fuel filter and turned key on pump primes but aint a drop of fuel coming out, and primed it few times as well as cranked over and nothing is coming out even turned fuel pump on manually from relay inputs and with pump whirring away nothing comes out so guessing there's another filter underneath bed or by tank but thats a tomorrow show finished for tonight update tomorrow with finding. Lmk if there's anything to be aware of with this scenario.


jp2code said:


> Nissan doesn't have another fuel filter besides the one in the engine compartment.
> 
> It sounds like the fuel line is clogged or the steel line got crushed shut.


Well remembered i had a pump transfer tool so i hooked up too filter feed and started to pump out air until fuel came out and eventually it did so answers that, but question on the electrical side of things do these trucks have a constant power submitted to anything? Notice that everytime i attempt to start truck my ecu goes out like the 2 leds on top but whenever quit starting it comes back on, disconnected negative terminal and hooked up voltage meter and shiws 11.1 when touching neg terminal and neg batt post? Currently at truck so any info would be awesome i wouldn't think there should be anything taking power unless ignition turned on or something left on but this truck has shown things id never knew about smh appreciated.


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## BSERIES18C407 (Mar 17, 2020)

Ok if i disconnect the thick black wire that seems to be a transfer or bridge like connector at fuseable links the volts drop dramatically to like 3v from 11.1v is it normal for these fuseable links things to draw power or is there a possible short it that circuit gonna look at diagram too see exactly what its for.


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## jp2code (Jun 2, 2011)

On the fusible links, one provides power to the fuse box, one provides power to the injectors and there might be a 3rd. They changed slightly from year to year. The battery should be around 13.2 or 13.8 volts. If the battery voltage drops that much whenever you connect the fusible link, the battery is weak and you have a short somewhere in your wiring.


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## BSERIES18C407 (Mar 17, 2020)

No it drops on negative terminal and post, from the top with issue and steps to figure where/why causing my fuel pump not to work- turn key on ecu comes on i hear a clump sound everytime ignition turned to just on normal sound of pump priming no problem. Truck isn't running though so when i disconnected filter since (obviously no fuel) ran line into bottle go turn ignition to prim system go back and bottle empty air or crushed fuel line in fuel system got pump and hooked up to feed and pumped until fuel was showing prim system again zero gas in bottle jump fuel relay itself to see results if done manually and whats happening is i hear the initial noise made whenever fuel pump is turned on but no wherring sound when ear next to tank as if pump isnt being turned on but when ignition switch on/off sounds like its coming on so then noticed ecu shuts off when starting the truck where leaves me with this fuseable link/ ground circuit short problem, and know where to make it stop to where no power detected on body ground which is the (thick black single wire fuseable link) when disconnected from harness side negative side voltage drops 11.1 to 3v if connect test light to neg batt term and test light in fuseable link mentioned above harness side light is dim disconnect all 3 ecu plugs test lights out. Sweet issue falls between cabin to batt inputs possibly however doesn't answer why fuel pump wont work when manually jumped at relay but gives off initial sound as if working being the clunk sound ? Gonna check out the harness plug by tank like fsm says and see where it stands is there anything else should try to check aside from the million wires fro cab to batt inputs? Oh also started with fuse by fuse to relays in underdash fuse box to no luck so its noted. 

If i had the cash to blow 600 Holley would call it a day !!!!!


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## rogoman (Dec 16, 2004)

BSERIES18C407 said:


> No it drops on negative terminal and post, from the top with issue and steps to figure where/why causing my fuel pump not to work- turn key on ecu comes on i hear a clump sound everytime ignition turned to just on normal sound of pump priming no problem. Truck isn't running though so when i disconnected filter since (obviously no fuel) ran line into bottle go turn ignition to prim system go back and bottle empty air or crushed fuel line in fuel system got pump and hooked up to feed and pumped until fuel was showing prim system again zero gas in bottle jump fuel relay itself to see results if done manually and whats happening is i hear the initial noise made whenever fuel pump is turned on but no wherring sound when ear next to tank as if pump isnt being turned on but when ignition switch on/off sounds like its coming on so then noticed ecu shuts off when starting the truck where leaves me with this fuseable link/ ground circuit short problem, and know where to make it stop to where no power detected on body ground which is the (thick black single wire fuseable link) when disconnected from harness side negative side voltage drops 11.1 to 3v if connect test light to neg batt term and test light in fuseable link mentioned above harness side light is dim disconnect all 3 ecu plugs test lights out. Sweet issue falls between cabin to batt inputs possibly however doesn't answer why fuel pump wont work when manually jumped at relay but gives off initial sound as if working being the clunk sound ? Gonna check out the harness plug by tank like fsm says and see where it stands is there anything else should try to check aside from the million wires fro cab to batt inputs? Oh also started with fuse by fuse to relays in underdash fuse box to no luck so its noted.
> 
> If i had the cash to blow 600 Holley would call it a day !!!!!


With everything in your vehicle *turned off*, the battery should have a *static* charge of 12.2-12.6 volts. If it's below 12v, either the battery is bad or the alternator is not charging the battery properly or there is a short somewhere in the system.

Assuming the charging system voltage is OK and the battery is good, the next thing to do would be to have a parasitic draw test performed; there should not be more than a 50 milliamp draw on the system with the ignition switch in the *"OFF"* position. If there is a higher draw, you need to do some testing to find out where the draw is coming from. Remove fuses one at a time until the draw goes away or falls into acceptable range.


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## jp2code (Jun 2, 2011)

@BSERIES18C407 Your last reply is difficult to understand. Several sentences are joined together and I think some words might be substituted for incorrect words with similar sounds. Were you using a Voice-To-Text program? Or perhaps English is not your primary language.

It sounds like you were calling the big black wire to the frame ground your Negative Fusible Link. There is a big cable coming off of the Negative Terminal on your battery that goes to the frame and then on to the engine and starter, but it is not a Fusible Link. There is also a Black Fusible Link that provides power to various small items (gauges, power steering/oil pressure switch, bulb check relay, interlock switch), but it should be connected to the Positive Battery Terminal.

It's hard to help when I can't follow your replies.


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## BSERIES18C407 (Mar 17, 2020)

Shit !!! Your breaking my heart when you say those hurtful things !!!! Lol smh !!! Ok rather then even look at what is supposedly not understood, update ::: sup fellas ? I know- i know !!! You guys missed me !!!! Well cheer up got !!! Got something to inform everyone about, raggedy asss truck is finally runing !!!!!! meaning upon complete turning of ignition key engine actually starts up !!!!!! Bout had a stroke when it first happened which was Wednesday night. Now that the exciting part is said now on with what is making this truck tic ? Ok in regards to the thick black wire aka fuseable link yes there is if you have the Se v6 which may not matter trim/eng but from the postive post clamp with box attached there's two plugs leaving from it plug #1 has 4 wires running into another plug and plug #2 leaving from terminal blk box is a single but twice the size of those other 4 wires on plug #1 also goes into another plug and then i believe is where harness gets its power to fusebox/relays from well if i disconnect the thick black wire on plug #2 on postive terminal ( bare with me now focus !!!!) Test light goes down brightness wise tremendous amount so i have a short to ground somewhere between batt and ecu. Here's were it heads beyond my ability to understand how truck works.

Ordered inline fuel pump since my last post explain how no fuel coming out feed line before filter easier to install inline pump than drop tank to replace factory pump, rerouted the wht/blu wire that powered the stock pump and installed two filters before and after inline unit, unfortunately to make everything work ecu&pump it has to be forced meaning fuel and main relays jumped cause ecu's ground side switch pin #6 blu/red wire that activates relay to power ecu and power fuel relay doesn't work so Ecu wont even come on when ignition on engine off and also upon starting engine the moment last turn is engaged the ecu led's shut off and wont come on until i shut off the truck and ignition is back in 2 turn position, so truck will run kinda ruff but will run even though the ecu shows no sign of being on since red & green lights go out whenever starting the motor. Lmfao but least its geting some where now dissecting the harness from batt to ecu why truck always had code 51 injector circuit cause the grounding side is being shorted. Lmk if something i can check save me time and heart ache!!


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## BSERIES18C407 (Mar 17, 2020)

Does anyone know about the circuitry inside vg30i ecu particularly transistors ?


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## jp2code (Jun 2, 2011)

BSERIES18C407 said:


> Does anyone know about the circuitry inside vg30i ecu particularly transistors ?


A company called Jim Wolf Technology does, but they charge a lot for their services and don't tell what they have learned.





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## BSERIES18C407 (Mar 17, 2020)

Lol smh yeah when i need my rb26dett reflashed they will be the first i call. Smh problem i got is transistor code off transistor thats blown isnt easy to obtain being its from 30yrs ago so tryin to figure what is equivalent to it, skycraft (electrical heaven) has anything you can think of just not knowledgeable people and even with transistor code they dont have anything matching but if i could figure out whats equivalent they might have something? 😦 
Either that or buy another ecu so attempting the cost effective route before buy second ecu. Appreciated that though.


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## smj999smj (Jan 1, 2006)

Last I heard, JWT doesn't work on Nissan ECM's, anymore. For those that need repairs to their ECM, they can try Circuit Board Medics. If you need a custom ECM program on a later, programmable ECM, UpRev would be the place to go.


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## BSERIES18C407 (Mar 17, 2020)

Well really all i need is a capacitor and or resistor replaced, ecu isnt sending ground signal to main relay which then activates fuel p relay, and recently replaced transistor that was blown but no luck at moment


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## BSERIES18C407 (Mar 17, 2020)

Sup fellas, well ordered the transistor or equivalent to factory since isnt easily to get being 30+ yr old technology ,but replaced part and ecu works but the ground side switch that grounds main relay still isn't working so if pins aren't jumped then ecu wont come on, and aside from sweet idle and ability to rev past 2800 (limp mode) isnt an issue anymore, but upon taking it for a test drive couldn't go any faster than 45mph and strong smell of unburned fuel. So off top im thinking tps sen/connection or maybe cylinder head coolant sens, first thing gonna do is a self diagnostics test with ecu to see exactly what may be the issue, will update with info when its done and again appreciated everyone's help and info that's been shared with me, was a big help being my first none honda vehicle, will get back with update on codes given.


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## jp2code (Jun 2, 2011)

Both TPS and Coolant Sensor are codes that would be in the ECU, so you are following the right path.


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