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issue I'm having is in the truck trailer wiring harness somewhere I believe?. The left turn light is getting constant 12v even when the truck is off and the right blinker does not blink, running lights power on fine, trailer brakes activate fine truck acknowledges the trailer.
all fuses appear to be fine, trucks lights do not exhibit the same symptoms however it does blink fast on the left side. But as far as I know these circuits are separate and the trailer is ran through it's one fuses and the TCM?
Just an update got to the trailer control module. Pulled the connector and checked the pin on the module pin 1 on connector c2496c yellow wire cat06 that's showing a constant 12v.
so I'm guessing my TCM is in need of replacement? It seems to pull its power from fuse 10 and fuse 90 in the battery junction box.
Problem: Left trailer turn signal had constant 12v. When using the left signal, the right flasher would blink. (Side note: also had an 800mA draw on the maxi fuse link.)
Diagnostics Performed:
Tested trailer plug and connector.
Cleaned and scrubbed all connectors.
Repaired a wire that was rubbed halfway through at a plug under the steering wheel.
Verified grounds, continuity, and all fuses.
Pulled the connector at the trailer control module (TCM) and found constant 12v coming from it.
Checked everything between the TCM, BCM, and data wires.
Opened the TCM, cleaned out dust/dirt, but issue remained.
Fix:
Replaced the Trailer Control Module with a new unit. Problem solved.
Bonus: This also fixed an odd blink issue I was having with the truck’s normal flashers, even though trailer and truck flashers are on separate circuits.
