# 88 nissan HD No check engine light at all



## hepcat75 (Aug 21, 2007)

88 Nissan HD I am trying to get the codes from my ECM and have noticed that there is no check engine light on my truck. I even took the instrument panel out to see if there was a light out but nope.

So do I have to remove my seat to check the diode light on the ECM because I do not see any light at all even in total darkness?

I need to see what codes are there because I have the safe mode where it is hitting the rev limitor at 2500. Sometimes if I feather the gas I can get it to go past the limitor and rev higher.

Please help


----------



## veesix (Jul 18, 2004)

You can see the codes flash, just by looking under the back of the seat (slide it foward). It unbolts and come out in a snap though.


----------



## spat (Oct 15, 2005)

Yeah you need to pull codes from the ECM itself I have seen some where the cover is improperly mounted and blocks the view of the LED lights. Not sure but it sounds more like one of the coils is cutting out so you might need to look into that. I'll try to find my post from a few years back on that issue. For starters go to the sticky in the front of the forum to get info on how to pull codes.


----------



## hepcat75 (Aug 21, 2007)

The cover is off the ECM but I don't see any lights at all with the seat all the way forward. I take I have to unbolt the ECM and then I should be able the see the lights to get codes. 

I only see one sparkplug wire coming from the middle of the cap to the coil so where is the other one?

Thanks


----------



## spat (Oct 15, 2005)

The cover is off the ECM but I don't see any lights at all with the seat all the way forward. I take I have to unbolt the ECM and then I should be able the see the lights to get codes. 

_*Not sure which side the LEDs are on the 88, my 86 has them on the back.*_


I only see one sparkplug wire coming from the middle of the cap to the coil so where is the other one?

_*Oh! my bad! I had assumed it was a 4cyl. since no details were given. Or am I wrong all together? I thought 88 had the Z engine for 4cyl which is dual ignition.*_


----------



## veesix (Jul 18, 2004)

You won't see the small lamps, because they are on the inside of the box and on the top front. You should be able to see the green and red light, when the small bulbs start flashing out the code.

What kind of truck is it?


----------



## hepcat75 (Aug 21, 2007)

Sorry guys 
88 Nissan truck Z 2.4 banger

the lights might be so dirty on top that they arn't showing any lights bright enough to see.
I will remove it so I can and will get back with the codes if it works.

the distributor I only see one wire in the middle going over to one coil. where is the other coil wire coming out of on the distributor?


----------



## hepcat75 (Aug 21, 2007)

Ok I had to remove seat to see lights to get codes.

Here is what I got
24 throttle valve switch
21 Ignition signal
23 Idle switch

So what do i check and how to get this 2500 rev limitor off?


----------



## smj999smj (Jan 1, 2006)

88 Z24i should have two coil assys. mounted side by side on the driver's front of the engine compartment. There should be four spark plugs on the intake side of the head and four on the exhaust side (or, 8 s. plugs total). This obviously would mean 8 ignition wires to the distributor cap and two coil wires. There were a couple of years that the NAP-Z engines had a conventional, 4 plug ignition system. There was a 2.0L NAP-Z engine used in 1980 ( I think) that had such a set-up. Maybe somebody converted the ignition system over or maybe swapped the engine? Who knows? I would look at the head. You should have 4 spark plug on the intake side of the head no matter which NAP-Z engine you have. So, what's on the exhaust side? Are there spark plugs with no wires to them...or plugged spark plug holes?...then somebody probably converted to a conventional 4-plug style ignition system (for whatever reason?). If there are no spark plug holes machined in the exhaust side of the head, possibly someone swapped a differant head or engine would be my guess.


----------



## hepcat75 (Aug 21, 2007)

well after looking at the distributor a little more clearly I did notice another middle wire following the exhaust wires and then coming back to the second coil. I should of looked a little closer.

The exhaust coil seems to not be firing at all so I switched the coils( I mean I unbolted them(two bolts that go all the way through the coils that hold it to the bracket) and swapped the coils since the harness were different and the truck fired up and no spark on the exhaust again even with switching the coil wires. 

The truck will run when i even hook up the exhaust spark plug wire from the distrubutor to the good intake coil( the one closer to the engine). 

what to do?


----------



## spat (Oct 15, 2005)

hepcat75 said:


> well after looking at the distributor a little more clearly I did notice another middle wire following the exhaust wires and then coming back to the second coil. I should of looked a little closer.
> 
> The exhaust coil seems to not be firing at all so I switched the coils( I mean I unbolted them(two bolts that go all the way through the coils that hold it to the bracket) and swapped the coils since the harness were different and the truck fired up and no spark on the exhaust again even with switching the coil wires.
> 
> ...


You most likely have a bad coil or ignition module this is quit tricky to solve sometimes and seems to have some slight variations on the wiring set-up from year to year but they all seem to have the same module failures. Do you have a Multi-meter? Did you swap just the coil, or the coil asymbly which would include the ignition module?


----------



## spat (Oct 15, 2005)

OK I dug out my old documents on the Z24i ignition and I put them in a RAR file on rapidshare. It also includes a basic how to on the use of a multi meter for those not experienced in that area. It also includes a schematic of the ignition system plus a basic diagnostic plan I wrote specific to this system. Hope this helps!

Z24i Ignition Diagnostics


----------



## hepcat75 (Aug 21, 2007)

Spat thanks for the information I will check into my exhaust coil transister per your instructions. 

question is the exhaust coil transister is bad would this cause the computer to go into safe mode?


----------



## hepcat75 (Aug 21, 2007)

Ok here is what I know for sure.

The Intake side isn't firing. I know for sure both coils are good because I swapped them. the intake ignition module isn't working because it is getting power and a ground.

One thing i noticed is that the bad intake ignition module showed 12 volts going into the coil and the good exhaust module going to the coil shows .652 volts. So i am assuming that the exhaust module shouldn't be letting power straight time.

any thoughts on this


----------



## hepcat75 (Aug 21, 2007)

Spat thanks very much for doing that me


----------



## spat (Oct 15, 2005)

Can't remember any specifics on the readings but that sounds just like what I was having problems with. I knew from others in the shop, I used to work in, had many of the same type problems and would spend days trying to fix them. That is why I wrote the diagnostic guide. I don't claim to be an expert on the issue by any means just simply tried to follow the steps I took in my diagnosis in hopes to help out others. It's much easier to travel through a maze when you have a map! (hey I like that)


----------



## mazdaverx7 (Dec 20, 2005)

i was reading my owners manual for my 89 and i saw that only CA models came with the check engine light.. i wonder why.....


----------



## spat (Oct 15, 2005)

mazdaverx7 said:


> i was reading my owners manual for my 89 and i saw that only CA models came with the check engine light.. i wonder why.....


California models have advanced emissions on them. Don't really know much on the Cali stuff back then. I didn't really start seeing cali emissions on vehicles untile the OBDII stuff came out. Then the Cali stuff seemed to show up more often for some reason.

If you want to know if you have federal or cali emissions look at the lable on the under side of the hood. It should tell you on that lable. At least the OBDII vehicles do and I asumm that ID requirment came out during the late 60's or early 70's at the latest.


----------

