Reverse lights not working. Please Help

[MisterM]

Have had no reverse lights since I bought the truck and I'm finally sick of it. Replaced the bulbs, nothing. Not sure if there is specifically a reverse light fuse but all the rear light fuses are fine. Figured the only other thing it could be is the reverse safety switch that's located on the transmission. Changed that, still nothing. Before I changed the switch I tested the switch and there was nothing, but I tested the thing that plugs into the switch and it was live so I'm not sure what to think of that. Anyone have this problem before???

 

[mduryea88]

i had the same problem on my truck. a new switch didn't work for me. inside the shifter housing on the shifter there is a nub that pushes on the switch. it wears out over time. i just wired in a toggle switch to bypass the switch. i tried different length switches from diffent manufactures to no avail

 

[98_k1500]

Jump out the switch with a jumper wire. If they work, your reverse pin is worn or stuck, not sure if they are spring loaded in these transmissions. If they still don't work, I'd lean more towards the tail light circuit boards or the connections/grounds under the bed.

 

[MisterM]

inside the shifter housing on the shifter there is a nub that pushes on the switch. it wears out over time. i just wired in a toggle switch to bypass the switch. i tried different length switches from diffent manufactures to no avail

So there's no way to replace the "nub"? I haven't looked at it yet to see what you're talking about. And when you say you tried different length switches to no avail are you saying the toggle switch you wired up didn't work?

 

[MisterM]

Jump out the switch with a jumper wire. If they work, your reverse pin is worn or stuck, not sure if they are spring loaded in these transmissions.

I'm not sure what you mean by jump out the switch. I tested the switch with a test light with the key in the "on" position and went from neutral to first to reverse and it never lit, I tried both terminals within the switch too. Yet the the part that plugs into the switch (not sure exactly what you'd call that) lights up only in reverse.

 

[great white]

You need to follow the circuit back rather than just chucking parts at it.

A simple test light will suffice.

Start at the tail light socket.

Remove the bulb and look for power. If none, check at the connector for power. None?

Slide under the truck, disconnect the frame to bed connector and check for power.

And so on working your way forward until you end up back at the power feed.

As soon as you find power in the circuit, you know the problem in downstream from that point.

It's a pretty simple circuit:

http://www.gmtruckcentral.com/wiringdiagrams/1995/1995-GMC-k1500-Ext Lights-Main.pdf

Power, switch, wiring, bulbs. Pretty simple.

The tail light circuit boards are highly suspect items for failure on these trucks. Pop the tail lights out and remove the connector to test for power. It's right at the start point for tracing the power back anyways.

If you have power at the connector but not at the bulb socket, you've found your problem.

I will stress again: you need to troubleshoot and trace it back from the lights. Don't throw parts at it until you know the issue.

 

[great white]

here's a little bit of TSB info related to no reverse lights as well:

Bulletin No.: 01-07-30-021

Date: May, 2001

TECHNICAL

Subject:
Park/Neutral Position Switch Connector Cannot Be Removed
(Replace Switch and Connectors)

Models:
1997-2001 Chevrolet Camaro, Corvette
1997-2001 Pontiac Firebird
1995-2001 Chevrolet and GMC S/T Models
1996-2001 Chevrolet and GMC C/K, M/L, G and P Models
1996-2001 Oldsmobile Bravada
with 4L60E (M30), 4L65E (M32),
4LBOE (MT1) or Allison LCT (M74) Automatic Transmission

This bulletin is being revised to change a labor operation number, add models, model years and transmission designations. Please discard Corporate Bulletin Number 83-71-10A (Section 7 - Transmission).

Condition

Technicians may experience difficulty in removing the connectors from the Park/Neutral Position Switch, usually when trying to remove the switch during transmission service. In rare cases, customers may also report switch related electrical conditions, such as improper or no shift indication, or no back-up light operation.

Cause

High ambient heat may cause the sealing compound in the switch to melt and flow into the connectors, sealing the connectors to the switch. This normally causes no customer concerns, but may cause an open circuit in rare cases.

Correction

In many cases, the switch can be removed and reinstalled without removing the connectors. If the switch is being removed as part of transmission service, and there are no switch related conditions, the switch can simply be reinstalled.

Some applications have a mounting bolt behind the connectors. The switch will have to be removed and will probably be damaged in the process.

The connector pigtails use wires which are all the same color. Use the old connector as a pattern to ensure that the new wires are connected to the harness correctly.

Important : This switch is in a wet area. It is very important to solder the wires and use heat-shrink tubing to ensure water-tight connections.

 

[MisterM]

Thanks great white, I'm going to trace it tonight after work. Ill let you know how it goes. Thanks everybody else for your responses too