[shakenfake]

Looking for the reverse light wiring diagram from the big connector back. My driver side reverse light works but my passenger does not. I have replaced the socket and the bulb but nothing. Socket and bulb are both known good as I tested them on the driver side. I am only getting .5V to my passenger side and something like 10.5V to my driver.
I see that there is a large 3 wire connector near the gas tank that goes up and then splits off into multiple different wires heading towards the tail lights. I believe that I just have a break in one of the wires there. What is interesting is that my passenger side socket only had two wires whereas my driver had 3 wires, passenger had the provisions for 3 wires but only utilized the outside two. I am using ACDelco P/N: LS253 which is identical to what is on there currently.

Please advise, this is one of the last things holding me back from being road worthy.

 

[1slow96]

Tail light harness is your problem. Taken many apart ,and factory splices become corroded over time.
Only way to fix permanent is to remove rear bumper cover,and unwrap tail light harness for careful inspection.

 

[Z09B4U]

I do not know how the entire reverse circuit on the 96 is routed but if you get switched voltage at the socket take 1slow96's suggestion and start at the tail light harness.

What is interesting is that my passenger side socket only had two wires whereas my driver had 3 wires, passenger had the provisions for 3 wires but only utilized the outside two.

If you mean this as three wires it is just the factory "daisy chaining" Read this:

Replacing Tail Light Sockets - 4 Wire Part Number, and...

It's been a few years since I logged-on, and it's time to get the '96's tail lights to work. Question 1: What is the replacement part number for the four-wire outboard tail light socket? Rock Auto only has the three-wire socket p/n 12003757... Question 2: When splicing-in replacement...

www.impalassforum.com

If I understand the way you describe your problem you may have a bad connection between the left and right socket light green wire circuit or a bad ground. Driver's side bulb works but passenger's side does not light.

If you want to check your back up light switch you can check it at C400 driver's side rear fender in the trunk.

Use a known good ground and check your passenger side socket green wire. If the test light lights up on passenger and drivers you have a ground problem. Lights on driver's side only it is the reverse wire between the sockets.

A test light will not light when there is a corrosion or contact problem, BUT a voltage meter may show perfect voltage on the same circuit.

If I had to repair the tail light harness I would upgrade all the ground wires. Separate 14ga ground wires to the left and right tail lights AND a separate 14ga ground to the fuel pump/gas gauge plug. I did this when I wired in extra brake lights and the sequential turn signal wiring.

You have put a lot of time and money into this car, get a FSM. 1996 has some one year only wiring, different fuse positions, etc. It would be safer to have the 96 FSM than get bad information from the wrong year diagram.

 

[1slow96]

No excuse not to have service manuals if you plan on working on this car. Mistakes can be very costly.

 

[shakenfake]

No when I say my passenger side had two wires to the socket and driver side had three I mean it, they are not in the same hole. I’ll take a picture when I return on Tuesday but in the picture you posted one of those wires is in the middle slot on the driver side.

I have one. Can’t find it. When I do I will scan every page and upload it. It is in one of three houses and I have scaled them top to bottom but I will keep looking.

 

[1slow96]

Take harness apart ,and you'll see/understand why it's the way it is.

 

[Z09B4U]

No when I say my passenger side had two wires to the socket and driver side had three I mean it, they are not in the same hole. I’ll take a picture when I return on Tuesday but in the picture you posted one of those wires is in the middle slot on the driver side.

The reverse bulb is a 2057 just like the brake/tail light bulb. If the socket is replaced it would have to be the three wire socket but stock wiring only uses the ground and bright filament. Someone may have changed the socket or it might be a 1996 only thing where GM used a three wire because it was cheaper or they did not want to re order the two wire.

To my knowledge this would not change the way the tail harness is wired. One reverse wire is connected to the other in the reverse circuit and all the rear light and tank grounds are spliced off one wire from the trunk.

have one. Can’t find it.

General sugestion to all: I have each of my FSMs in a brief case with diagrams and information on repairs and modifications. That way if I am working on the cars somewhere I have a easy way to make sure I have them all when I leave. It is easier to find a brief case if some one moves it than just the FSM.

 

[shakenfake]

Do you really have to pull the bumper cover off the car to remove the wiring harness? I find that somewhat hard to believe. It looks like you could almost squeeze it out the bottom perhaps if you undid some of the gas tank filler neck.

Not at the car right now just bored on vacation.

 

[Z09B4U]

It was years ago but I added the four sequential wires, two grounds, and two extra brake wires without removing the bumper cover or playing with the filler neck. My memory (right or wrong) is you can remove the harness without any major work. The hard parts were the harness to the tank and the licence plate lights. I may not have removed the harness but I got enough access to do the work.

 

[1slow96]

To inspect harness? It really should be removed. Making a custom harness right now w/o all the individual wires. Fuel pump will have it's own dedicated harness ,seperate ground/power/sender from tail light harness. Tail lights also unplug from harness unlike from factory.

 

[shakenfake]

No I understand that the harness needs to be removed for inspection but that seems almost nonsensical that GM installed the harness in such a way that you need to pull the bumper cover off. Could be wrong though, I will probably take a look at it again tonight.

Need to order some braided wire loom to cover it up over the electrical tape.

 

[1slow96]

May surprise you that automakers can't make allowances for what some owner may want ,and/or need to do 25+ years later. Especially considering only 2-3% of car owners work on their own cars.

 

[shakenfake]

Oh I know all about that lol
I just feel like this is something that would need to be relatively serviceable by a non-owner.

 

[Z09B4U]

Before you remove the bumper cover try just the top.
Remove the tail lights, licence plate mount, and the top bumper cover fasteners.

Then unplug the tank harness and remove any fasteners.
Unplug the harness in the trunk. Pop out the grommet and feed the harness through the sheet metal.
Pry back the top of the bumper cover and remove harness. There may be a fastener or two.
(red line follows the harness)

Correct or not this is what I remember doing.

 

[91ss]

Removing the cover is very simple. And if you use a 1/4 air ratchet to get the nuts down in the quarters, it goes pretty quickly.

 

[shakenfake]

I was able to wiggle the harness back out and back in so no need to pull the cover.

Fixed the issue.

As you can see a new replacement socket actually has the wiring wrong, sorta. I ended up removing the brown wire from the socket on both sides and on the driver side soldering the dark and light green to the white and then passenger side just light green to white. I guess the brown wire is for something else. Anyways I fixed the issue and rewrapped the entire tail lamp wiring harness in new electrical tape, all the old stuff off and some new on.