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x1957x

2012 ltz silverado p/u trailer plug dont have blinkers or brake lights etc. just running lights

9 posts in this topic

My new pick up trailer (7 pin) plug dont work. It is a 2012 chevy silverado. All it has is the lights when I turn them on. Dont have turn signals, flashers, brake lights etc. Any ideas where to look? Thanks

Edited by x1957x

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The owners manual fuse information. All* trucks usually have the trailer fused separate from the truck to prevent your trailer leaving you stranded without lights. The running lights prove that you have some power and a good ground to the adapter.

 

It may be worth while to get a trailer adapter that has LEDs for testing the plug to determine if there is a truck or trailer fault. Sometimes the plug cover will say what the pins are for and you can get a test light to verify function of the adapter. Place the alligator clamp to the ground pin turn on the right blinker and place the probe on the right blinker/brake pin. If the cover doesn't show the pin out, Google will.

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5 hours ago, JOHNBIGDOG said:

The owners manual fuse information. All* trucks usually have the trailer fused separate from the truck to prevent your trailer leaving you stranded without lights. The running lights prove that you have some power and a good ground to the adapter.

 

It may be worth while to get a trailer adapter that has LEDs for testing the plug to determine if there is a truck or trailer fault. Sometimes the plug cover will say what the pins are for and you can get a test light to verify function of the adapter. Place the alligator clamp to the ground pin turn on the right blinker and place the probe on the right blinker/brake pin. If the cover doesn't show the pin out, Google will.

Tried it and didnt get any power. flashed a couple times

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Trailer fuses are in the fuse block under the hood. Each item has its own fuse.  Left turn ,right turn, brake etc.. Cant think they would all be out at the same time. Have you hooked a trailer with bad wiring up to it recently?

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Check the vehicle wiring for a good ground; if it's had bodywork or was in an accident, there might be hidden damage with poor grounds or cut wires, seen a lot of that. The next thing I'd then check is to make sure the wires on the trailer plug are wired properly to the trailer. If you have a 4-Way connector on the trailer the white wire is for ground, the green wire for right turn and brake, yellow wire for left turn and brake, and the brown wire is for running lights. 
If the wiring is all correct then you will need to check the trailer connector on the vehicle and trailer for a good ground connection issue, or a short on the tail light circuit on the trailer. Open them up and make sure there is no white or green corrosion causing a problem inside the connectors. If there is, clean them out or replace the connectors with new ones.
If you can't find the problem in the connectors,  follow the trailer wiring and check all of the grounds for all of the lights and the trailer connector. Make sure each light is grounded to the trailer frame and that the connection to the trailer frame is free of rust, paint, corrosion,etc.  Other lights like running lights down the side of the trailer might have a separate ground wire or they may be grounded through the mounting hardware so you will need to check each of these lights. 
While you are checking all of the ground connections, it's a good idea to look at all of the wiring and check for pinched or cut, frayed wires that could be causing your problem, an replace any wiring sections as needed with a good soldered joint, covered with shrink-fit tubing. Good luck! 

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Check fuse 1 and fuse 3 in the underhood fuse block. these are the right and left and or stop lamp fuses for the trailer. If those are good you will likely need a scan tool to see if the BCM is controlling the relays for those circuits.

It doesn't sound like a ground issue. Grounds usually do funky things. all the lights will flash with the turn signals on or everything turns off when you step on the brakes.

You can also back probe the fuses in the fueblock to see if there is power at the fuses with the turn signals on. If there is power there and nothing at the seven pin than there is a problem with the wiring. The first thing I would do is start unplugging connectors, checking for corrosion, and checking for power at the pins in the connectors.

you will be looking for the yellow and dark green wires in the harness.

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I had this problem in my 05 Trailblazer, and it was the BCM. About a $20-30 part if I recall, and took me 5 minutes to replace, right under the dash by steering wheel. I did all the troubleshooting and could not figure it out, till some of the guys here (Airjer? Macgyver?..) told me about it. Good luck.

BTW the BCM is blinker control module or something like that, but it actually seems to do more than just blinkers.

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13 hours ago, BoxMN said:

I had this problem in my 05 Trailblazer, and it was the BCM. About a $20-30 part if I recall, and took me 5 minutes to replace, right under the dash by steering wheel. I did all the troubleshooting and could not figure it out, till some of the guys here (Airjer? Macgyver?..) told me about it. Good luck.

BTW the BCM is blinker control module or something like that, but it actually seems to do more than just blinkers.

You had a turn signal/hazard flasher module. Fairly inexpensive and easy to replace. The lights in questions are controlled by a body control module (BCM). This on board computer does much more than just the turn signal and could run you several hundred dollars to replace.

BoxMN likes this

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And that right there is why I am not a mechanic ;) 

Body Control Module, I learn something new everyday!

Jeremy airjer W likes this

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