Reverse light harness fried. Should I just replace the harness, or look further?

[willhaven]

The reverse light was working and switching on and off as expected. I think the switch is probably okay.

A few weeks ago while pulling the car out, I got smoke from under the dash. I figured I was feathering the clutch on the way out too lightly and made it smoke. This happened a week or so later while backing out. Again I assumed it was my gingerly easing the clutch as I pulled out that was the problem.

Turns out it was the reverse light switch harness coming from the transmission. It was burned all the way from the trans plug to a splice near the fuse box. Mine was routed through a hole in the trans tunnel and across where the pedals and up to the fuse box.

The fuse box is a Painless 30001. The power for the reverse was coming from the ACC plug (lower left). The splice was solid and was a larger gauge (16) than the original type wire (18). There is something else being fed from the ACC plug, but I haven't dug around to determine what it is yet.



Anyone have any similar experience? Anything obvious I should look at?

[7071 challenger]

You should look further. Originally, the reverse harness runs from the reverse switch at the transmission, follow the side cover, runs on the bellhousing and reaches the bulkhead connector. You said yours runs through the transmission tunnel. I suspect that one of the wire touched the sheetmetal, and fried. You should re-check your connections/ diagrams, because it should be protected by a fuse. If the harness fried, maybe there is no fuse in your circuit.

Robert

[willhaven]

The routing was suspect for sure. Having looked at a replacement harness I thought, "there's no way those original connectors went through the tiny hole in the trans tunnel."

Whatever it was connected to at the box had no fuse. The wire was burned to a crisp. Check it out...

[willhaven]

Looks like both the reverse switch wire and the ignition wire are coming from the ACC plug on the fuse box. I don't think either of those are properly fused (hence the burning wire).

The upside here is that the problem was likely in the harness itself, right? The ignition works just fine and the wires split off from the fuse box there all look good. The ignition wire goes from the ACC plug on the fuse box all the way to the column. I haven't traced it beyond there.

So, I either move the reverse light power to where it should be (w/radio on a 20 amp fuse), or I hack in an in-line 20 amp fuse for the new reverse harness? That sound about right?

Worse comes to worse, there's still a shorting issue, but it blows the fuse instead of frying my new harness?

[dodj]

The upside here is that the problem was likely in the harness itself, right? The ignition works just fine and the wires split off from the fuse box there all look good. The ignition wire goes from the ACC plug on the fuse box all the way to the column. I haven't traced it beyond there.

So, I either move the reverse light power to where it should be (w/radio on a 20 amp fuse), or I hack in an in-line 20 amp fuse for the new reverse harness? That sound about right?

Worse comes to worse, there's still a shorting issue, but it blows the fuse instead of frying my new harness?

Route and fuse it properly.

[willhaven]

Looking at the old wiring diagram, it doesn't look like the ignition is supposed to be fused anyway. Does that make sense?

So my guess is, they found an easy spot to patch into power for the reverse light instead of the proper (and harder to get to) location with the proper fuse. The harness happened to ground out somewhere, and there goes my harness. Luckily my whole car didn't go with it.

I was in my driveway and had my HalGuard extinguisher on me, but still, not something you want to have to do.

The reverse harness had been cable tied to some other wires here and there. Now I have to check those to make sure they aren't burned or exposed as well. Good times.

[7071 challenger]

Looks like both the reverse switch wire and the ignition wire are coming from the ACC plug on the fuse box. I don't think either of those are properly fused (hence the burning wire).

The upside here is that the problem was likely in the harness itself, right? The ignition works just fine and the wires split off from the fuse box there all look good. The ignition wire goes from the ACC plug on the fuse box all the way to the column. I haven't traced it beyond there.

So, I either move the reverse light power to where it should be (w/radio on a 20 amp fuse), or I hack in an in-line 20 amp fuse for the new reverse harness? That sound about right?

Worse comes to worse, there's still a shorting issue, but it blows the fuse instead of frying my new harness?

You're right, if it is fused, the fuse will blow instead of your harness. If you have to go though the transmission tunnel, enlarge the hole and install a rubber grommet to prevent this. I have to re-check the diagram, but if I remember well, your ignition, (originally), is protected by a fusible link in the engine compartment.

Robert

[willhaven]

Well, this weekend I replaced the harness and put a 20a inline fuse into the circuit. It was getting dark by the time I finished, so I'll give it a shot this week. Hopefully it doesn't burn up on me again. 

I also got my resistors in the blinker circuit so they'll work with the LED tail lights and front turn lights. I've still got some gremlins to debug there, as my headlights and front turn signals don't work together. 

[willhaven]

Well, the fuse blew. Guess I'll have to trace it all the way back through the harness to the lights to see if anything seems amiss.

 

[dodj]

Well, the fuse blew. Guess I'll have to trace it all the way back through the harness to the lights to see if anything seems amiss.

 

Unplug all the lights and replace the fuse. If it blows, it's a wire/insulation problem. If it doesn't blow, add one light at a time untill it blows to find the faulty piece.

[willhaven]

Being that it's just the reverse lights, you mean unplug the two reverse lights to try it out? Then plug them in one by one?

Sounds like a good idea BTW. I hadn't thought about that.

[dodj]

Actually, you could just unplug the tail light harness behind the drivers side kick panel.
Then replace the fuse, and put it in rev.
Or, if you are handy with a meter, check the resistance of the 12v feed wire from where the fuse would be, to ground. It should read infinite. If it shows close to zero, you have a wire problem somewhere from the power feed, to the trans switch, to the kick panel connector.
Your reverse wiring doesn't go through the original bulkhead connector, right?

[willhaven]

It's a Painless harness in the car. Some wires pass through the bulkhead connector area, but they just seem to be fed through and don't have any plastic plugs or anything.

I'm not sure if there are any other plugs along the path to the bulb. It was spliced directly from the starter wire, to the trans switch, then from the trans switch down toward the back end of the car under the carpet on the driver's side. I'll have to tear the seats out and give it another look after I get a meter reading. Thanks for the tip there.

I'll update here once I get around to getting it handled. It isn't stopping me from driving and I only have until the end of the month on my registration. I want to get in as much driving as possible before it's up. 

I have to have a state inspector come out and verify my VIN before I can re-up with my registration. Long story...