No passenger side trailer stop light.

DanD

Original poster
Member
Mar 23, 2014
46
Hewitt, WI
Just hooked up my 03 Trailblazer to a trailer today for the first time in a very long time. I have no right trailer brake light. Right blinker works fine. It uses the same terminal in the plug and the same wiring as the stop light. Confirmed no power with voltmeter when brake applied. All lights on truck work fine. All other functions on trailer are fine. Seem to be no fuses specifically for trailer brake lights as there are for blinkers. Any thoughts?
 

Reprise

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Jul 22, 2015
2,724
Check the back side of the 7-way plug for corrosion. It's a twist-lock connector.

When I got my first trailer last year, I had no brake lights, either. The tech who set up my hitch played with it, got the brake lights working, and I got home OK. I took it apart, found the corrosion, cleared it off, and problem solved.

Get some dielectric grease, too (small Permatex 1/8 oz tube is fine), and put some on the front side of the pins.
 

DanD

Original poster
Member
Mar 23, 2014
46
Hewitt, WI
Check the back side of the 7-way plug for corrosion. It's a twist-lock connector.

When I got my first trailer last year, I had no brake lights, either. The tech who set up my hitch played with it, got the brake lights working, and I got home OK. I took it apart, found the corrosion, cleared it off, and problem solved.

Get some dielectric grease, too (small Permatex 1/8 oz tube is fine), and put some on the front side of the pins.
All reasonable but the right blinker works perfectly. Same filament in bulb same wiring on trailer and same pin on the connectors. Left brake light is fine. Something wrong in truck somewhere.
 

Blckshdw

Moderator
Nov 20, 2011
10,665
Tampa Bay Area, FL
Looks like fuse 19 in the front block, and the brake signal from the rear block, both feed into "Trailer Brake Wiring (Blunt Cut)" **right side of page 1** which sounds like some type of module or bundle somewhere, but the wiring diagram doesn't note exactly where it is. My guess is the right brake connection might be loose, or the wire is damaged, and just needs a quick repair.
 

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Mooseman

Moderator
Dec 4, 2011
25,257
Ottawa, ON
That blunt cut is under the dash and is just that, four wires cut and taped. It's for hooking up a trailer brake controller.

In the schematic, If you follow the yellow and dk.green wires from the trailer connector, they go through fuses 50 and 51 under hood, then go to the turn signal module. That's what controls if it sends brake lights to both or just one and the other the turn signal. See what you're getting from the module at those wires for brake, left and right signals.
 

DanD

Original poster
Member
Mar 23, 2014
46
Hewitt, WI
That blunt cut is under the dash and is just that, four wires cut and taped. It's for hooking up a trailer brake controller.

In the schematic, If you follow the yellow and dk.green wires from the trailer connector, they go through fuses 50 and 51 under hood, then go to the turn signal module. That's what controls if it sends brake lights to both or just one and the other the turn signal. See what you're getting from the module at those wires for brake, left and right signals.
Thank you for the info. Please excuse my ignorance but where is the turn signal module?
 

DanD

Original poster
Member
Mar 23, 2014
46
Hewitt, WI
Just hooked up my 03 Trailblazer to a trailer today for the first time in a very long time. I have no right trailer brake light. Right blinker works fine. It uses the same terminal in the plug and the same wiring as the stop light. Confirmed no power with voltmeter when brake applied. All lights on truck work fine. All other functions on trailer are fine. Seem to be no fuses specifically for trailer brake lights as there are for blinkers. Any thoughts?
That blunt cut is under the dash and is just that, four wires cut and taped. It's for hooking up a trailer brake controller.

In the schematic, If you follow the yellow and dk.green wires from the trailer connector, they go through fuses 50 and 51 under hood, then go to the turn signal module. That's what controls if it sends brake lights to both or just one and the other the turn signal. See what you're getting from the module at those wires for brake, left and right signals.
Mooseman, just wanted to let you know I tested the green wire at the blinker module. Had output for blinker but nothing when step on brake. Went to parts store and bought a new module and installed and now working. Kind of strange that every function was fine on old module except for right trailer brake light but it was the culprit. Thank you so much for your help. Literally a 10 minute repair once I knew where to look.
 

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