# 1990 D21 King Cab P/U wont start ( electric problem)



## dplantz (Jul 7, 2008)

When I bought the truck I had an issue with truck not even engaging starter. Had starter and battery tested and both were OK. Turned out to be the fusible links and connections at the battery terminal, so replaced those with factory parts. Truck had been working fine since then ( 3 months ago) but now it is doing the same thing again. Truck will engage electric fuel pump ( I can hear it) and can hear the fuse box "click" but starter wont engage. Weird thing is if you let it sit a while sometimes it will go ahead and start right up. so problem is intermittent. Already pulled and re-tightened battery terminals but that had no affect. Any ideas? Only thing i can think of os possibly the switch at the clutch ( when you push in the clutch to start) Like I said it works sometimes though which is strange....


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## zanegrey (Dec 5, 2005)

check the fusiable links again ..
check the starter relay.

check all grounds to the starter..


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## dplantz (Jul 7, 2008)

*Starter relay*

Sorry to be a spaz, but what / where is the starter relay and how do I check it?


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## zanegrey (Dec 5, 2005)

the starter relay is between the main realy on the passenger fender well and the battery



it is blue and is usaully coupled with another blue realy ..
it should be the one closet to the fire wall..


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## Fred S (Aug 26, 2006)

I had a similar problem with my 95. It turned out that the ignition switch was the problem.

Take the covers off of your steering column and look on the left side of the ignition switch. There's an electrical switch there. It's round and held in place by one screw.
Take it off.

Put the key in the ignition and turn it to the Run position. Stick a screwdriver in the switch you removed and turn it clockwise. The engine should start.

If it does, you need to look into tightening down and/or shimming that round switch. Why Nissan chose to hold it in place with a single screw, I do not know.

Fred


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## dvdswanson (Nov 6, 2005)

next time it happens tap on the side of the starter with a wrench, if it starts right up replace the starter.


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## dplantz (Jul 7, 2008)

Turns out it was the switch down at the clutch pedal. Someone before me had taped a piece of plastic on the clutch lever to aid it in connecting with the switch when depressing the clutch to start it. I imagine it used to have a rubber grommet there, so I found one in my junk box and supeglued it to the tab on the pedal. Starts fine now!!!


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## baileyward (Dec 10, 2008)

My starter problem sounded just like yours.... after replacing the starter 5x, it turned out to be the little Y cable off of the starter.... cost my a whopping $15 for a new one


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## Pynikal (Dec 11, 2008)

dplantz said:


> Turns out it was the switch down at the clutch pedal. Someone before me had taped a piece of plastic on the clutch lever to aid it in connecting with the switch when depressing the clutch to start it. I imagine it used to have a rubber grommet there, so I found one in my junk box and supeglued it to the tab on the pedal. Starts fine now!!!


is there any way to totally bypass this? by connecting the wires all the time??


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## Fred S (Aug 26, 2006)

I'd bypass it with a switch on the dash.

Toyota did that on their 80's trucks and 4-runners. It was a button marked "Clutch Start Cancel" The idea was that if you'd broken down on the train tracks or in traffic, you could put it in first, hit this button and crank the starter to drive the vehicle a short distance.


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## smikster (Aug 12, 2008)

thats a great switch...glad nissan has them to....i use it all the time


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## Pynikal (Dec 11, 2008)

i work at toyota and totally didnt think about that. i h=guess the nissan is getting a toyota switch!:woowoo:


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## SteveO069 (May 21, 2021)

Ok, I've had similar problems. For some time my truck would not start unless I depressed the clutch hard to the floor for several seconds. Finally it stopped completely. After reading the fourum it seems likely the clutch pedal safety switch might be bad. Replaced it along with the starter relay and ignition release. Still won't start.
Battery and connections good. When I turn the key I can hear a click in the dash. 
Banged on the starter with a hammer. Nothing.
What Now?
SteveO


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## VStar650CL (Nov 12, 2020)

This should be your starting circuit, it's pretty simple. You can check pretty much everything that needs checking with a test light. I'm assuming you have a US model, if it's Canadian then skip all the clutch interlock stuff. Start at the Starter Solenoid and work backwards. These tests are _all_ with the clutch pushed and the key turned to Start, so having a Designated Key Turner will help:

1) You should see a solid 12V on B/Y at 66E. If you do, something is wrong with the starter or the hot cable. If you don't,
2) You should see solid 12V at both B/Y's and the B/P on the interlock relay. If you do, there's a break in the circuit between the relay and the solenoid, probably a crappy pin at 26M:56E. If you don't and there's no juice on B/Y, skip to 7. If there is juice on B/Y,
3) If the relay clicked when you turned the key but no juice came through to B/P, the relay is shot. If the relay didn't click,
4) You should see _no_ voltage on LG. If there's a dim light on LG, go to 5. If there's no light then the relay is shot (open coil).
5) Check B at the Interlock Switch. If you also see a dim light, the switch ground wire or ground connection is bad. If you don't,
6) Check LG at the Interlock Switch. If you see a dim light, the switch is bad. If you don't, the LG wire or connections are open somewhere.
7) Check B/Y at the Ignition Switch. If there's solid 12V then the B/Y wire or connections are open between the Ignition Switch and the Interlock Relay. If there's no 12V then the Ignition Switch is shot.

Hope this helps you.


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## VStar650CL (Nov 12, 2020)

PS - The earlier D21's had an "Interlock Emergency Switch" with it's own relay that basically shorted around the interlock, but the basic circuit and colors aren't different. It would take a very fluky wiring problem for the emergency circuit to _dis_able starting, so you should be able to ignore it if present.


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## SteveO069 (May 21, 2021)

VStar650CL said:


> View attachment 7414
> 
> 
> This should be your starting circuit, it's pretty simple. You can check pretty much everything that needs checking with a test light. I'm assuming you have a US model, if it's Canadian then skip all the clutch interlock stuff. Start at the Starter Solenoid and work backwards. These tests are _all_ with the clutch pushed and the key turned to Start, so having a Designated Key Turner will help:
> ...


Thanks, great useful info. I'll get my test light out and check things out.
SteveO





see what I can find


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## VStar650CL (Nov 12, 2020)

Happy to help, let us all know what you find.


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