87 no crank

[cerial]

1987 V10(4wd) 5.7 700r4
Truck would not crank today

I played around with the starter ignition switch(neutral safety switch) wiring was the issue.

I pulled the connections and found the blue wire was being pushed up so I pushed it down against the switch blade terminal, turned the key, and the truck started.

Shifted the thing from park to overdrive then back to park and then started it again.

The check engine light would come on then go out before I started it. Starter cranks strong and I have 2 1000 amp batteries connected together for 12 volts at 2000 cca.






Not wanting to be shut down for the loose wire. I pulled it and zip tied it the two wires back together then pushed it back in the switch making sure the terminals hit and the truck would not start.




Pulled the thing again and went out buying a new switch thinking it may be the contacts.

I plugged in the connections to the new switch off the column moving it where park should be and the thing will still not crank. Adjusted it around and moved it and still nothing.





Plastic part so I should be able to just set it into the park position having the thing hit the contacts, turn the key, and have the thing fire up. But still nothing there.

But curious if having the thing on the column does anything I installed it into the column and shifted it around before putting the thing into park and still nothing.


I think the orange/black and black/white should be a ground for the ecm.

I think the green and blue are just for the backup lights.


When I turn the key I get the service engine soon light and the break light coming on and no cranking.

I have power to the accessory terminal and to the backup light terminal when I turn the key to the on position.


Key on hot items grounded with test light





Key to accessory



Key to start with switch wired



When switch is not wired the service engine soon light does not come on just the break light lights up.








I want to install a floor shifter for the 700r4 and if possible BYPASS this switch all together.

I installed different taillights so do not have reverse lights currently. I have no problem putting them on a toggle switch.



I have a black/white, orange/black, wire on one plastic connection which goes to the ECM I believe.

Blue and green of the other connection which I believe just controls the back up lights.


But when trying to bypass the switch by connecting the orange/black and black/orange with a jumper wire the thing does not do anything different then when the switch is in place.



Kind of driving me nuts here.
Help please.

[4x4k30]

sounds like no fuel pressure.. check to see if the fuel pump is running

[cerial]

Pump will not turn on till engine gets 4psi. Have a inline pump and different tank which will be finalized soon as preventive maintenance. But currently running on one of the factory saddle tanks.

Engine is not cranking at all. No clunk or anything from starter.

Dropped starter and checked fuse able links with a probe and they are good. I have power from the battery up to the starter Battery lug.

Jumped the starters battery terminal to the S terminal and the thing fired right up.


So my starter and the wires coming off the battery to the starter are good

I have the key on power and the key is causing the break light to turn on when it is turned so those terminals "should" be good.

[RUN GMC]

Just had the same problem.......took out starter and it test good , checked out fusable links, all good.......bought a new neutral safety switch and seen where it has an adjustable movement by clicking it clockwise......went to the one in my 87 GMC and adjusted it 3 clicks to the right(clockwise).....my tuck has started up ever since that adjustment......my understanding is neutral safety sends power to ECM and if not adjusted properly for contact enough voltage doesnt make it to the ECM to work properly or at all.......

example of adjustment

https://www.cargurus.com/Cars/Discussion-c996_ds458153

[cerial]

Thanks man. I been there and played with adjusting it left and right with no success. Played with the new one before putting it up, then once it was up, then when it was back down. No go.

On to the ignition starter switch. The truck was unmodified stock when I got it. Used as a plow truck so under the dash is untouched short of a modification to the lights.

I am getting power to the neutral safety switch. But being 31 years old maybe something broke internally on the inside of the ignition starter switch. Truck has never required more then one turn of the key to start it. But maybe it has had enough this morning.


Going to the parts store tomorrow morning to get the new switch. Open to ideas what else this may be in case that is not it.








Here is the wiring of the thing. Outside of the neutral safety switch, and the ignition starter switch being bad. The thing should crank.

Below you can see that there is a inline fuse going to the crank signal. But that is after the T junction and the starter should still get power and engine crank.


So if this 2nd switch does not work I am in trouble. Open to ideas on what else it can be while I wait for the sun to come up.

[RUN GMC]

I also replaced the ignition stater module under the steering column 1st......i still had no crank after changing it out.....pulled starter and tested good.....another thing is the neutral switch can be reset by clicking it all the way to the left then start adjusting it to the right....

[cerial]

I installed the new switch and the thing fired up on the 2nd crank and I then ran it 2/3 more starts and on the 4th time once again it refuses to crank.




Came across the above picture and ran a jumper wire from Batt2 to the coil/crank and batt to s terminal and nothing so I have a bad wire somewhere.


Going to run a 10 gauge wire from the s terminal on the ignition switch to the starter S terminal leaving the old wiring in place which will back feed the crank signal back to the ECM so it knows to add more fuel during cranking.
This will eliminate the neutral switch and the thing will crank when the key is turned.


Next summer I am installing a affordable fuel injection harness. Before this all happened I was about to run the electrical and finalize the plumbing for the fuel system using a inline pump (new tank) to work with the affordable harness. But that is getting pushed back till I get this thing starting reliably.

[cerial]

Ok so that did not work.

I ran some `10 gauge off a battery to a switch and then tied it into my "bypass" wire going down to the starter S post.

Flipped the switch and nothing.
I have power through the switch but I guess I have something wrong with the starter. Which is weird because when I hit the thing with a screwdriver hitting the batt and S post it cranks. Maybe something is messed up internally and shaking itself lose after 2 or 3 starts.
That's my guess anyway.

So off to the parts store I go.

[cerial]

That was it.

Old starter must have had a flat spot on it somewhere. 31 years old and used mainly as a plow truck I could not blame it. But wow what a headache to find.

Turned that thing over 2 times by jumping batt to S terminal and when it did crank it was powerful as heck thanks to 2 batteries making 1850 cca turning it.

$70 in parts and I have a new ignition system in place.