GM Repair Problems? Ask GM Repair Expert Now.
Hi there, I am Cam.With your flasher module, what brand did you install? Was it new or used?
Its basically a couple small relays inside that split the circuits up for truck and trailer. The fast flashing was possibly a failed relay. This one though, it should still light them up. Let me get you a schematic.
OK, do the brake lights work and I didn't ask you about the hazard lights?
If the FLASH fuse gets power with the key on then I am really thinking you have a problem with the flasher and replacement should be considered especially if you have warranty.
here is the schematic.