Today I installed a new reverse switch in my '89. Because some previous owner had cut the harness and bypassed the reverse lamps to operate via a flip switch on the instrument panel I had to reattach the four wires to the harness and cut the wires they had running to the flip switch. I matched the colors correctly and connected them back together. There was a purple wire, a black wire with a pink stripe, and two gray wires with red stripes. After I connected everything together my reverse lights still would not operate. Not only that, my truck would not start! So in order to get my reverse lights to work again I had to reattach the purple wire, and the black with pink wire back to the flip switch hoping that the reverse lights would operate....which they did. But my truck still would not start. So I decided to join the two gray wires with red stripes back together as they were and the truck fired right up.

Any idea what is going on here?

 

Sounds like an issue with the neutral safety switch. The two gray w/red wires you tied back together are bypassing the switch. Is it a stick or an auto?

 

Blk-pink is the Reverse wire from transmission
Ppl-org is the power from fuse block to transmission

these two are joined by switch in/on trans.... they actually are lights control

red-blue(gray-red) are the Park Neutral safety starter interlock....

 

The truck has a C6 auto.

So the neutral safety switch is the problem? Since they bypassed the whole thing altogether I am going to assume that this is a very difficult part to change?

 

Ok someone's gotta ask, did you adjust the switch after you put it on?

If not that would likely explain why the lights didn't work and the truck wouldn't start once you had it all wired up.

If not put the shift lever in neutral, loosen the two switch retaining bolts, rotate and insert a #32 drill bit (shank end) into the gauge pin holes of the switch (insert bit 31/64 of an inch), tighten the switch retainer bolts and remove drill bit. Test for proper operation, reverse lights should light in reverse, engine should start in park and neutral only.

 

actually not difficult at all 2 or 3 screws and an electrical plug if I remember correctly and easy access.
on the side of the trans with the shift linkage.

 

You must be talking about the neutral safety switch? The only switch that I have installed yet is the reverse switch, and there didn't seem to be any way to adjust it. Just tighten it all the way and its in.

But if I do need to change the neutral safety switch, which appears to be so; all I need to do is follow the instructions you gave?

 

NSS and reverse light switch on the C6 is the same animal. the grey/red wires are the NSS, the black/pink and purple/orange wires are for the reverse lights.
once they are hooked up, follow the adjustment instructions above and everything will work properly.

 

I tried to remove the NSS switch today but had a difficult time trying to loosen that one nut that holds on the linkage. As soon as I try to torque on it the lever wants to push the linkage in the small rubber boot. There appears to be no easy to hold onto this thing either. I tried wedging a screwdriver in between the lever and the side of the NSS. That didn't work so I tried to tie the lever back with some heavy electrical wire, that didn't work either, the wire just stretched. Is there some sort of a trick to remove this stupid thing? If I wrench on it to hard it will obviously break.

 

did you try to start the truck in neutral if you do and it still wont start then its the nss

 

It's definitely the NSS. Only problem I'm having now is trying to loosen that one nut holding on the linkage. Every time I put the wrench to it the lever moves with the nut and puts stress on the linkage. It's really hard to put a good amount of torque on it for this reason. Are there any tricks in removing this thing?

 

i have never had a need to remove a NSS/reverse switch.
are you trying to remove it to test it, or because it is bad?

did you try hooking it up and then try to start the truck while moving the shifter through the gear ranges? it may just be way out of alignment.

 

The switch was bypassed some years ago by a previous owner. Four wires were cut, two were spliced together and two more were wired to a flip switch on the dash to power the reverse lamps. I bought a new reverse switch thinking that it was bypassed because it was bad. Well, I reattached the four wires and the reverse lamps still would not work, and the truck would not start in any gear. I already have a new one on order for $32 from Advance Auto. It should probably be replaced anyways since the harness is really mangled on it. I just need to remove that one pesky nut without damaging the linkage.