Brake Light stumper

[chevyCowboy]

I put the bed on the 00 crew cab and got a new junk yard tail light harness off of a suburban (its one that had the towing package from the factory so it has trailer wiring built in), mine was shot off the 93. I plugged the lights in and i had Brake, left and right turn, reverse, but no tails. found broken wires on the truck side of the weatherpack connector, tails completly broke and some of the other barly hanging on. I cut the wires and rebuilt the weather pack.

I now have tails, left & right turn, reverse, and brakes work but they pop the fuse every time.

I have checked every place that i messed with while trying to solve the tail light issue no bare wires or any thant looks bad. I even disconected the whole rear light harness, at the weatherpack in rear, and still pop fuses so its not in the trailer wireing or the lights. Also i DO NOT have contenuity to ground so i have ruled out a dead short, the fuse dose not pop right away either it takes a few seconds.

I ran out of fuses so when i was at the store buying more i got a 25amp breaker for testing and it will not pop it, it dose get quite warm though, it will pop a 30amp fuse though.

im at a loss at to whats going on here as well as with my power door lock problem which is in another thread

 

[WarWagon]

You got a high resistance short to ground. (as opposed to a "bang" dead short to ground.) Aside of bad bulbs nothing else makes sense. So corroded wire or wire rubbed through on a rusty spot.

Does the fuse pop with the bulbs out?

 

[chevyCowboy]

yes
i got to thinking this evening that the third break light is still in the system when i had the others un-pluged so maybe it is where my problem is, i took it to the wash bay last week so maybe i got some water in it or the bulb went out. i will be checking that out tomorow

 

[chevyCowboy]

Got them working. Did a whole lot of investigating to have the problem be right in front of my face.
At the rear of the truck where the weather pack is at there was a single White wire. Not connected to any thing and there is a bolt that was used for a ground with an old eyelet on it. I assumed that this white wire went there, i guess i thought it wa sa ground. I finally disconected that white wire from the frame and all is well. But now im trying to figure out what that wire is for. Im thinking maybe the license plate light?



thought i would share this.

View attachment scan0001.pdf

 

[NVW]

Good catch, use a test light and see what powers it.

 

[chevyCowboy]

that was going to be my next step but i had to come in i was about frozen. it was half way nice when i got home so i droped a couple layers and then in the next 2 hr i think it droped 10 degrees and hadnt even gotten dark yet.

 

[WarWagon]

Looked at my 1993 and I don't have that wire. CHMSL was introduced in 1994, so this may be for the camper CHMSL. Color matches diagram and your symptoms. Grounds are usually black and it makes no sense to run a ground that far back. Trailer ground is white though. Probably spliced into the brake lights somehow in the bed wiring?

I would work on your frame to battery, engine grounds as they appear to be weak. Should have popped a fuse or breaker with no lights grounded like that...

 

[chevyCowboy]

the lights are grounded to the bed in the tail light harness, and all grounds have been rebuilt with new ends/wire when i put the engine in. Truck hasnt left drive way yet

 

[chevyCowboy]

i saw that about the CHMSL but have no idea what it is?

 

[WarWagon]

CHMSL, Center High Mount Stop Lamp, aka 3rd brake light. Campers sometimes have these and the laws I am not clear on if the new campers have to have a 3rd brake light...
Must be that the wire can only carry so much current and did not pop the breaker or bad breaker? Regardless, it appears you found the issue.

 

[chevyCowboy]

ya just one of those odd ball problems, when you look back at them you say to your self well now i just spent 3hrs trying to figure that out and burned up about 15 fuses and it was right in front of me the whole time. I guess what got me was that on trailers white is ground.