Hey guys! I have a 98 c1500.

So when I use my turn signal either left or right, it just turns on the hazards, when the lights are off.

when I turn the lights on, the blinkers on the dash stay lite and do nothing when you flip the switch either left or right.

I’ve changed the multi-function switch and relay already. I have no idea where to go from there. Any help would be much appreciated .

 

It sounds like a short or open for one of the relay circuits. I can’t recall if the relay for your truck is stand-alone or if it plugs into the fuse box, so you may not be able to see the wire colors, but here’s what you should have -

1) Battery voltage on the light blue wire with the key on - comes from the turn/back up fuse (15A) via multi-function switch.

2) Ground on the black wire - grounds at the left end of the dash (typically behind the kick panel).

3) The gray wire is the hazard input from the multi-function switch - with the hazards on, you should have battery voltage - comes from the stop/hazard fuse (20A) and is a direct battery feed via multi-function switch.

4) The purple wire is the flasher out signal - whether using turn or hazards, this is what feeds back to the multi-function switch and on to the bulbs.

The easiest way to isolate the problem area (before or after switch) is gonna be to disconnect only the purple wire from the switch (or relay, whatever’s easiest) and use an incandescent test light as the load. Operate the individual turn signals and hazards - if you get the same results as you’re seeing now, the problem is likely in the wiring between the switch and relay (steering column). If it operates normally, the issue is downstream of the relay - it could still be in the column wiring but could also be in the harness running to the bulbs.