Good morning!

I'm hoping there is someone out there that is available to help me with this problem. I've done some substantial reading on other forums regarding brake lights with the Jeep Grand Cherokees but can't seem to figure this one out.

Last month the bulbs in my brake light assemblies melted their plastic housing causing the everything to go south. I just replaced the whole assembly (both sides) and it looks as if all three bulbs are working. The tail lights light up when the headlights are turned on, the blinkers work as does the backup lights. All but the brake lights seem to be in working order.

I know the brake lights currently aren't working because every time I try and put a fuse into the brake light slot it immediately sparks and pops. So I'm at a loss, I don't see any fraying or damage to the wires going to the tail lights and really don't know what else to check.

Any help here would be greatly appreciated.

Kyle

 

Instantly popping fuses are a sure indication of a short circuit. Check all the wiring going to the tail lights and the brake light switch. See if the fuse holds up with the 4-way flasher on. Then hit the brake. If the fuse is good with the flashers on, I'd suspect the brake switch circuit.

 

Thank you Dave,

I tried putting the 4-way flashers and inserting the fuse but it instantly sparked and blew.

I just replaced the brake switch last night and these things are still happening so I'm guessing I need to inspect the brake light wires from front to back to see if there is an issue there?

I'm not that electrically inclined so any tips on what/where to look for the short would be immensely helpful.

Thank you again!

 

I have to ask, right size fuse? Eliminate the easy first lol
I would start with taking one of the brake light bulbs out and see if it pops the fuse when you hit the brake, then try the same on the other side. Then with no bulbs. Or vice versa. This will help narrow down your search for your short. Go from there. I would also eliminate the brake light switch, check for continuity on the positive wire of the harness to each brake light. Look for variances. You can also check for continuity from the same wire to different parts of the body, which will also help narrow down the search. Better continuity means you are closer to the short.

 

I have the right size fuse yes...

I've trying putting the fuse in with the assemblies removed and same result.

I don't even need to try and press the brake, when I try to put the fuse in it's immediately sparking. I tried to put the fuse in when the brake switch was removed and there was a loud humming noise but no sparking.

 

You have a short to ground somewhere between the fuse panel and the brake light switch. Has there been any work done to the dash or anything?

 

My apologies, I read the post slightly wrong. I thought it only happened when you hit the brake. I agree with the above, short between the switch and panel...Don't know why it would buzz without the switch versus popping. I looked at the wiring diagram for my 2004, it appears there is a wire pk/db that goes from fuse 23 to the switch. The brake switch signal wire comes from the PCM and its a wh/pk wire.The secondary brake switch is between the shifter and pcm and is also wh/pk. So, with it humming and not popping...check the PCM area and the shifter assembly area for the hum

 

Thank you all so much for the help.

I think I found my culprit. I removed the tubing that bundles the wires leading to the brake switch and found that the brake light wires (white/tan I think) have melted and look like crap. They've melted into and around everything around them. I'm assuming I need to remove the bad section and replace the wires and hopefully that will work.

Would it be possible for this to be found along the bright light wires from the front to the back? Or would this normally be localized where I already have failure?

 

Any indication as to why they may have had an issue? Rubbing anywhere, exposed to excessive heat, moisture, etc? It could just be a result of a different problem...I guess the only way to really know it to cut that portion out, patch it and before putting anything together, test it. Don't forget to disconnect the battery!

 

I plan on fixing the wires tonight and thank you for the note about disconnecting the battery. A knucklehead like myself would have never thought of that. Thanks!!!

 

All those wires down there, you'd be sure to hit things against some metal or other exposed wires.
It's easy to get caught up in the drama and miss the simple things.

 

Yeah I'm sure...

Seriously though, I really appreciate your guys help with this. I feel like I've been chasing my tail for the past couple weeks.

 

That's why were all here. Keep us posted.

 

This burnt section probably happened when your tailights shorted out. I'm surprised the fuse didn't blow first.

 

All right so I've finally cut out the bad section of wires and replaced them all.

The fuse is continuing to blow but I can at least place it in it's appropriate slot. Before it would instantly spark now it just blows when the brake is applied. Could the brake switch (new just bought it last week) have blown in the time that I've been waiting to fix the wires? I think that I just need to replace that again but I'm not sure. I am trying to do everything I can before following all the wires front to back to look for more melted/failed areas.