What a wild ride. After about a month, several hundred dollars and lot of black nitrile gloves, I've gotten my 1996 XJ baselined and up to snuff. I even made sure all the bulbs are correct to ensure correct amperage draw. But a problem I hope I might have somehow corrected is still raising its ugly head.

By process of elimination, it appears the 20A maxi fuse in the PDC under the hood blows every time I start the car. That is, I have no blinkers, hazards and brake light whenever I decide I want to operate the car. I have confirmed if the vehicle is off and I put in a new 20A fuse, I have working blinkers, hazards and brake light. Start the car? The fuse blows and those features are gone. All the fuses in the kick panel below the steering wheel are intact and the relay works fine when the fuse is intact to allow those features to work.

Has anyone else experienced this sort of problem? I'm not 100% certain whether the wiring harness for this '96 is for '96 and earlier years or '97 and up (as 1996 was a transitional year for the XJ), so I wouldn't even know what wiring diagram to refer to. Suffice it to say, this is pretty frustrating, so any help is greatly appreciated.

 

Have you measured your system/alternator voltage during startup?

My guess is that your computer is sensing lack of voltage in the system, and is allowing the alternator to dump everything its got into the system. Normally the computer, allows the alternator to produce more voltage only as required to meet a certain threshold around 14.5v. But if the computer thinks it is measuring no/low voltage, it will falsely allow the alternator to produce much more than is needed.

Start by checking all connections, especially ground connections. (disconnect, clean until shiny, tightly reconnect).

But definitely get a multimeter on system voltage during startup to see what is happening.

 

If you find that system voltage is normal (around 14.5v) during/after startup. The next thing I would want to see would be the condition of the wires/connections under the PDC. If they are corroding and/or fusing together you can get strange conditions like this.

 

Well, sorry for the red herring. I spent a lot of time last night checking things. I could explain all the stuff I did but long story short and two test fuses later, I discovered application of the brake light is what's blowing the fuse. This is with accessories on and the vehicle off, so it has nothing to do with starting the Jeep.

Interestingly, it looks like the previous owner had put a splice on the white wire of the brake switch and had a blue wire coming off of that. Where it goes, I haven't determined yet, but it goes into the kick panel below the steering wheel. For giggles, I cleaned up the splice and taped it back up, put it back on and it blew another fuse. I have no idea what the purpose of this splice was as the Jeep, to my knowledge, has no immobilizer, ABS or remote starter.

At this point, I'm going to look for a short between the brake switch and the rear tail lights. I'll also check the grounds on the driver side rear quarter and any harness behind that panel.

 

Does it, or did it at one time, have a trailer hitch? Mine is a 97, but there was evidence of a white wire spliced at the brake switch, and a large blue wire that ended at the driver side taillight, that was spliced into the trailer hitch convertor box. Found another wire running under the cargo sill plate, spliced into the passenger side taillight for the brake and turn signal.

 

Check the bulb sockets for corrosion.

 

Here you go dude it's an easy fix , but it was a pain the *** to find the issue when it was happening to me. Hope this helps you.

https://www.cherokeeforum.com/f2/fus...pplied-210550/

 

You know when I saw this, I was a little skeptical. But I thought it would be easy to try before I start looking for shorts, so what the heck. Coming to the Jeep, stone cold, without accessories, the light delay relay was hot. The pigtail wasn't melted, but the relay was definitely not supposed to be that hot to the touch (not like burn yourself hot, but you know). So, I pulled it.

Popped in my 20A circuit breaker and tested the lights with accessories on. Tested with the headlights on and off, brake lights, turn signals, just about any combination. With the highest load, headlights on, brake lights on and turn signals going, I didn't have any problem using the circuit breaker. The only thing I noticed was the click from the fuse box as I turned the ignition off and pulled the key out, but that should be normal.

So, yeah, thanks for saving me all that multimeter detectivery with this simple solution. Frankly, I hate courtesy lights, so no love lost. I will double check things with a regular fuse in, but this looks very good for me. IMO, your solution should be stickied.

 

Glad I could help