Brake and Left Turn Signal Lights

[jeboyd]

When pressing the brake pedal the left turn signal lights come on. They don't flash but both the front and back light up along with the indicator on the dash.

I removed the rear tail light assemblies and unplugged the circuit board along with removing the front bulb and the indicator still lights up on the dash when pressing the brake pedal.

The only way to keep them from coming on with the brake pedal pressed is to remove the left turn fuse under the rear seat.

Any one have any ideas where to look next?

Thanks to a suggestion from the Trialvoy forum I have downloaded the service manual so I can take a look at the wiring diagrams and see what the brake light circuit and the left turn signal circuit have in common.

Thanks for the help.

Jack

 

[The_Roadie]

There could be a short in the wiring, since those circuits normally have nothing in common. HOWEVER, they *do* both come together at the flasher module up above the driver's feet. The connection is that the flasher module also combines the brake and turn signal signals into one signal that then goes to the trailer connector. It could have an internal fault. Trailers share a common filament/signal for turn signals and brake lights. The truck has separate lamps.

View attachment 28118

 

[jeboyd]

Thanks for the reply.

After reviewing the wiring diagram I was going to go ahead and replace the flasher module.

This is very intermittent but my wife said last night that now the left signal stops flashing when applying the brake. At first the left signal still flashed properly even when applying the brake.

Thanks again.

Jack

 

[jeboyd]

The flasher module seems to have fixed it. Thanks for your help.

 

[The_Roadie]

Makes everybody here feel good to help with a free diagnosis. Thanks for the report back. Need any more help - you know where the community lives now.