Brake wiring help?!

[One1999Chev]

I was told my rear left signal wasn't working when I had a friend following me. Soon after it seemed like when I brake that side also did not light up. I also noticed that neither of my licence plate lights were working.

My front signal light is working fine, and my right rear signal and brake lights are working as well...Any ideas? I am thinking possibly it's the wiring harness under the box that connects all the rear electrical to the front. I know on my truck there is some type of plugin that *HAD* all the wires going into it, and I had to splice them all together because they'd mostly all broken from previous owner. I figured I spliced them good, but this is making me think twice.

Does anyone know which plug i am talking about? Also know where I could potentially order a new one from!? I am going to investigate into those wires more tomorrow, but if they are all connected and my light still won't work I just am not sure what the problem may be. (Anyone know the wire colours and their corresponding lights btw?) Thanks.

EDIT: I have wire brushed and put in a new ground bolt/nut for all the rear electrical. Maybe it is not grounding well enough?

 

[east302]

Here are the diagnostics for one rear brake/turn lamp not working on a 1998, hope it helps...

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[1994]

Thanks. That is alot of info. to take in...might take me awhile to decipher.

 

[east302]

Do you have a multimeter?




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[1994]

No unfortunately.

 

[east302]

Grab a cheap one from a big box store, I can walk you through the diagnostic table if you need.


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[east302]

One thing you can do without the multimeter, is find ground #401...

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...and follow the black wire up, it should have a splice with one black wire going to each taillamp and one to the license plate lamps. See if the one between that splice and the left taillamp wiring harness is damaged.


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[1994]

Hey East thanks for all your knowledge and help.
I went to try checking wiring on the truck tonight after work and had a small test light so I checked for power on YELLOW and GREEN wire. These wires seem to be the left signal and left brake light (when pedal pushed). I had power going into that trailer harness plug and also coming out the end of the plug that connects to the tail light circuit board.

I found my problem.
My aftermarket LED tail light bulb needed to be flipped.
Rookie mistake I know, but I did not try this easy diagnostic even though it had been in the back of my head since I was told my left signal wasn't working.

What happened was I had replacement circuit boards for my clear tails, but the plug for these do not like to hold the stock wiring harness plug too well. Switched back onto the stock circuit boards so the plug fit better. I distinctly remember sitting on my ******* and changing these from one set of tails to the other. I also remember pulling out LEDs and stock bulbs and changing them around between the two sets....obviously this is where I replaced one of the 6 lights opposite to how it should have been!

Anyways, I found it weird that the LED still worked (although it was plugged in incorrectly) but it just didn't seem to do the functions it also has (brake light and signal)

I re-spliced and crimped one of the wires with a new connector and electrical taped them all again. Let's hope they hold up now!