Turn signal not working

Hello,

It sounds like the BCM might be bad, but to be sure let's check the fuses that run the system. Here is a guide to help check for power at the fuses and the blinker wiring diagrams below so you can see how it works and the BCM location as well:

https://www.2carpros.com/articles/how-to-check-a-car-fuse

Check out the diagrams (below). Please let us know what you find. We are interested to see what it is.

Did you check for voltage at left turn fuse, everything turned on? The circled fuse gets voltage from flasher module. If no voltage, could be flasher module problem or wiring to the fuse?

Any voltage at all? With key on, engine off, what is voltage reading across battery posts? The reading should be close to the same at the fuse. Generally around 12 volts, maybe a little less if engine isn't running.

Compare voltage at other turn fuses, the ones that work.

Yeah, a flasher module, if the same.

Glad you got it going your way.

Sounds as if you have a short across the brake and indicator light, do you have a trailer plug fitted? If so make sure all wires in the back of the plug are insulated and free from rust and contamination that my case a short. If no plug, pull the globes from the brake lights and see if the indicators still stop with your foot on the brake, if yes, replace one globe and re test, if fault returns you know which side to start looking for short.

Hello.

It sounds like you have a wiring problem or the BCM is bad and needs to be replaced but to be sure lets check all fuses for the truck none can be out.

https://www.2carpros.com/articles/how-to-check-a-car-fuse

Next you need to check the wiring for the system. here is a guide and the wiring diagrams along with the BCM and fuse locations:

https://www.2carpros.com/articles/how-to-check-wiring

Check out the diagrams (below). Please let us know what happens. If it is the BCM you may need to have it programmed if you cannot find a used one.

Cheers, Ken

Yes, check all fuses. Also, check the wiring continuity and if everything checks out I would replace the BCM.

Hello,

It sounds like the flasher module has gone out but to be sure here is the blinker wiring diagrams and a guide to help check the power and ground circuits with the location of the flasher module below.

https://www.2carpros.com/articles/how-to-check-wiring

Check out the diagrams (Below). Please let us know what you find. We are interested to see what it is.

I just wanted to provide you the wiring diagrams so you can check wires and make sure you got the correct fuses. The reason I say that is that the wiring layout for the triler lights on this truck are confusing and use there own circuit fuses as well as some of the trucks light system fuses.
The first diagram shows the, "STUD #!" Fuse which is a 40 Amp fuse. The second diagram is harder to follow wires, 1 to the Trailer fuse 15 Amp, wire7 to Left Trailer turn signal fuse 10 Amp, Wire 8 to right Trilaer Turn signal fuse 10 Amp and wire 11 to the under hood fuse/relay box to the Left turn signal 10 Amp.
Then back in the cab at the Light control box in the fuse box under dash, there is a main fuse for the Flash Unit that is 25 Amps.

Otherwise follow turn signal wires for coninutiy with a multi-meter up to the fuse box and check the connector and terminals at the fuse box.

Let me know if you have any questions.