Two Very Important stupid Question(s)...

[Ashton84W]

So I’m dumbfounded at this truck. I’ve had it for awhile and it’s always had some issues but now more than ever. 85 Chevy K10. 305/Turbo 350.
I’ve never had reverse lights. As far as I know also this truck has been an automatic since the start. Ive looked at what I could and kinda speechless.

Question (1)- Do I have the wrong neutral safety switch?

My neutral safety switch located at the base of the colum has only two spades on it with a blue and green wire to it.

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I thought that only the manual trans had that and the automatic had four. Am I wrong? If not then where are the missing two wires and what are they for?

....and....

Quite simply put one day I have lights and the next day I don’t. I’m talking about my dash lights and the running lights/brake lights. I understand that they are all on the same circuit therefore related probably to a single problem. They stopped working while driving AT NIGHT going through Atlanta. Very unsafe mind you.

I recently replaced all the tailights and they worked fine after that + none are burnt. Now idk what might have happened but I’ve checked grounds (including the one at the driver side tailight) and checked fuses and traced wires for anything burnt or cut and even changed out my HEADLIGHT SWITCH but that was a no go. Now as I understand there is a brown wire leading from the switch that runs to all those lights.

Now for me that wire splits into two. Both ends just so happen to not be connected to anything (see pic). One wire is very short and the other goes over the steering colum and comes out next to the “radio” area.

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Question (2)- Where are those wires supposed to connect to? Did they become unplugged or wha?

Any help or comments/ suggestions are appreciated. Not electrically inclined to DC so please dumb it down for me. I can take pics of whatever is needed. Thanks in advamce

 

[Snoots]

They stopped working while driving AT NIGHT going through Atlanta.

Not unusual if you're running from the Popo.

There's a ground block just above the parking brake. Take it off. Clean everything and put it back on. They have a nasty habit of causing a LOT of electrical problems and are commonly overlooked.

 

[Preston]

Have you used a test light to see what the brown wire does or doesn’t do? I would trace the circuit down, there are wiring diagrams under the vendors sections that should help some, I am challenged under the dash for age and I wear bifocals and have a hard time seeing if I had a rotisserie it would help but anyway we will help you through this. I’m troubleshooting a electrician issue with my fan/ ac circuit now.

 

[Arkansas_V8]

See those prongs sticking out far left? Those are what snoots is talking about. Under the purple wire.

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Mine has the brown and black wire to it.

 

[Preston]

I also believe if you put the headlight switch back in the dash will ground the switch as well, I know it limits your visibility.

 

[chengny]

Question (1)- Do I have the wrong neutral safety switch?

My neutral safety switch located at the base of the colum has only two spades on it with a blue and green wire to it.

By 1985 the NSS had been eliminated and was replaced with a mechanical interlock in the upper part of the steering column. The ignition switch can only be rotated if the gear selector is in P or N. The DK BLU and LT GRN leads shown above are used to activate the back up lights.


Question (2)- Where are those wires supposed to connect to? Did they become unplugged or wha?

Those two BRN leads are for: roof marker lights (the short one) and a radio with some type of optional upgrades (the longer lead). If you don't have roof markers or a special radio they don't need to connect to anything.

The BRN wire you are concerned with is connected to terminal 4 - as shown here:

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That lead supplies power to the parking/marker (front & rear) and license plate lamps. The dash lights are powered by the same fused source. But that power is first lead through the rheostat then back to the fuse block. At the block it passes through the INST LPS fuse. After leaving the fuse block it then goes to the panel lamps, radio back lighting and HVAC control panel.

The brake lights have no connection to the lighting circuits noted above.

If you are losing all lighting in the rear end, I would look again at the grounding.

 

[Ashton84W]

Question (1)- Do I have the wrong neutral safety switch?

My neutral safety switch located at the base of the colum has only two spades on it with a blue and green wire to it.

By 1985 the NSS had been eliminated and was replaced with a mechanical interlock in the upper part of the steering column. The ignition switch can only be rotated if the gear selector is in P or N. The DK BLU and LT GRN leads shown above are used to activate the back up lights.


Question (2)- Where are those wires supposed to connect to? Did they become unplugged or wha?

Those two BRN leads are for: roof marker lights (the short one) and a radio with some type of optional upgrades (the longer lead). If you don't have roof markers or a special radio they don't need to connect to anything.

The BRN wire you are concerned with is connected to terminal 4 - as shown here:

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That lead supplies power to the parking/marker (front & rear) and license plate lamps. The dash lights are powered by the same fused source. But that power is first lead through the rheostat then back to the fuse block. At the block it passes through the INST LPS fuse. After leaving the fuse block it then goes to the panel lamps, radio back lighting and HVAC control panel.

The brake lights have no connection to the lighting circuits noted above.

If you are losing all lighting in the rear end, I would look again at the grounding.

Awesome info, thank you. If that be the case then I now have more questions than answers. I can see now that those two wires that were split are indeed for the lights and radio. No need to worry about those. Are you saying that that white switch isn’t the neutral safety switch? If not then what is it?

I actually got my reverse lights to work with the adjustment of the slider so that’s a plus.

I’m looking for the INST LPS fuse on my fuse block but cannot seem to find it. The letters are mostly rubbed off and I don’t appear to have a regular fuse box. I’ve already checked all fuses but would like to know where the wires are to test them.

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Still no brake lights but one problem at a time. What to look for now?

 

[Ashton84W]

I also believe if you put the headlight switch back in the dash will ground the switch as well, I know it limits your visibility.

That’s what the white wire acts as if I’m correct? The ground?

 

[Ashton84W]

See those prongs sticking out far left? Those are what snoots is talking about. Under the purple wire.

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Mine has the brown and black wire to it.

All the prongs are clean. One of the first things I looked at under the dash. Actually had a ground come out for the wiper blades but that was a minor issue quickly resolved.

 

[Ashton84W]

Not unusual if you're running from the Popo.

There's a ground block just above the parking brake. Take it off. Clean everything and put it back on. They have a nasty habit of causing a LOT of electrical problems and are commonly overlooked.

My 305 isn’t getting far running from the police

 

[Arkansas_V8]

My 305 isn’t getting far running from the police

With the rewiring I did yesterday, I had a huge light problem for a bit.

It was a switch, on the column, by the ignition rod, it wasnt snug. I had no brake lights, or turn signals. Atleast they worked after I found that.

 

[chengny]

Are you saying that that white switch isn’t the neutral safety switch? If not then what is it?

I actually got my reverse lights to work with the adjustment of the slider so that’s a plus.

That is the switch for the B/U lights - see post #6.


I’m looking for the INST LPS fuse on my fuse block but cannot seem to find it. The letters are mostly rubbed off and I don’t appear to have a regular fuse box. I’ve already checked all fuses but would like to know where the wires are to test them.

Its the 15A fuse traced in yellow (BTW - it should be a 5A fuse):

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Also, you appear to have the appropriate fuse block for your truck. Compare to the dwg below which was taken from the 1985 wiring manual:

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All the legible fuse socket markings on your block match up with the dwg from the manual. If you had the wrong fuse block it would be apparent. The changes from year to year were not subtle. Not only were the fuse locations different, the body of the fuse block changed as well.


That’s what the white wire acts as if I’m correct? The ground?

If the rheostat is turned all the way to the stop (I can't recall if its CW or CCW), a set of contacts closes and creates a ground path for the dome and courtesy lights. Same as if you open the doors. One leg of those lights is always supplied with battery voltage - they are illuminated when the other leg is grounded.

 

[Snoots]

All the prongs are clean. One of the first things I looked at under the dash. Actually had a ground come out for the wiper blades but that was a minor issue quickly resolved.

Not just the prongs. Remove the 'prong' block. That's where you'll likely find rust.