1995 6.5 T/D Blake Light Fuse Gremlin

[Aftermath]

Hello all,

I have an electrical issue that I cannot seem to find out where. My brake light fuse keeps blowing. It will not blow while holding the brake and sitting still. I have pressed the brake pedal while violently shaking the truck to try to get it to blow and it wont. i thought that because I just installed 2 new optima red top batteries that it may be getting too much power, so that maybe I needed to go from a 20 amp fuse to a 30 amp. That was a mistake. I melted the brake pedal switch and the 6" harness that connects to it. Luckily I had another used switch and harness. Problem remained, so I then disconnected the following : brake controller, cruise control, abs, rear tail lights, to see if it was one of those, it wasn't. I then took it to a transmission shop and they told me that it was definetly the TCC Solenoid in the transmission, so I replaced that, and of course, it didn't fix the problem. I have checked all the wiring from the rear of the truck where my trailer lights and brake controller connector is located, all the way to the fuse panel looking for a naked spot to no avail. Could it be the ignition switch? Has anyone ever heard of this issue before? Thanks for any advise :eek:

[a5150nut]

Welcome to TDP there Aftermath.

Don't know if you have search capabilities yet but you might look here
http://www.thedieselpageforums.com/tdpforum/search.php?searchid=310576
These are all threads related to brake light fuse.

[Aftermath]

Yep, went through search and the link you provided very carefully. I can't really pinpoint what my problem may be from prior posts. My turn signals are working, and even after the fuse blows, I can manually turn the brake lights on at the controller without smoking any wires. Do you think that would point to maybe a relay before the brake switch ? Thanks for all the help!

[More Power]

Hello all,

I have an electrical issue that I cannot seem to find out where. My brake light fuse keeps blowing. It will not blow while holding the brake and sitting still. I have pressed the brake pedal while violently shaking the truck to try to get it to blow and it wont. i thought that because I just installed 2 new optima red top batteries that it may be getting too much power, so that maybe I needed to go from a 20 amp fuse to a 30 amp. That was a mistake. I melted the brake pedal switch and the 6" harness that connects to it. Luckily I had another used switch and harness. Problem remained, so I then disconnected the following : brake controller, cruise control, abs, rear tail lights, to see if it was one of those, it wasn't. I then took it to a transmission shop and they told me that it was definetly the TCC Solenoid in the transmission, so I replaced that, and of course, it didn't fix the problem. I have checked all the wiring from the rear of the truck where my trailer lights and brake controller connector is located, all the way to the fuse panel looking for a naked spot to no avail. Could it be the ignition switch? Has anyone ever heard of this issue before? Thanks for any advise :eek:

Welcome to the board!

The following image clip is for a 1996-98 brake circuit, but it should be the same as yours. You should look for places between the brake switch and the ECM where you can break the circuit, to help you determine where the short to ground is.

Since you mentioned the 6" length of wire burned, the short is not likely in the computer - the short is after the "S220" (splice) onward toward the brake lights.

http://www.thedieselpageforums.com/photopost/data/500/BrakeSwitch001.jpg

[Aftermath]

Welcome to the board!

The following image clip is for a 1996-98 brake circuit, but it should be the same as yours. You should look for places between the brake switch and the ECM where you can break the circuit, to help you determine where the short to ground is.

Since you mentioned the 6" length of wire burned, the short is not likely in the computer - the short is after the "S220" (splice) onward toward the brake lights.

http://www.thedieselpageforums.com/photopost/data/500/BrakeSwitch001.jpg

I have searched every white power wire from the split back and cannot find any naked spots to ground. I replaced the TCC solenoid in the trans, could it be the wiring harness in the trans? Again, I cannot get the fuse to blow unless in motion "go/ stop cycle" as if a trans solenoid or the internal harness is kicking back. I cannot get the fuse to blow idling or just sitting in run position with engine off no matter how long the pedal is pressed. Codes are 31, 38, 41. Tge 31 is EGR and I have a non EGR engine. Thanks for any advise

[Aftermath]

Does anyone know the wiring destinations/locations at the brake light switch or have a wiring diagram? I believe its 5-6 wires.

Thanks all !

[N9Phil]

I had the same problem years ago with a step van. It ended up being a pinched wire going to my break lights. It would work for days until you hit a bump and the wire shorted.I ended up running a new wire to them.

[JTodd]

The brake light signal from the pedal switch goes through the multi function switch in the steering column. This multi function switch controls the turn signals, brake lights, wipers and cruise control. You may have a short in there.