Light, Turn Signal Issue
 

So I'm having a light issue. When I turn on the headlight switch, the left turn signal comes on and stays on solid. Any thoughts?

Also, when I turn the headlight knob, my instrument lights flicker on and off. Do I need a new headlight switch?

I already replaced the turn signal flasher because the turn signals were screwed up before.

Re: Light, Turn Signal Issue
 

Check the grounds on both the front & rear turn signal light sockets. Also check the bulbs (both front & rear) to make sure they're the correct dual-contact bulbs ... 1157's I believe. I remember a case once where someone had jammed a single-contact 1156 bulb into a dual-contact socket. The bulb's single contact bridged across the socket's 2 contacts, shorting the parking light & turn signal circuits together.

I'd recommend cleaning the switch first to see if that helps. Do that by spraying some electrical contact cleaner on the switch's rheostat section ... that's the part that looks like a bare coiled wire. Then rotate the knob back & forth a few times and see if that takes care of the problem. If not, replace the switch.

Re: Light, Turn Signal Issue
 

Also check blinker relay? Round relay in the fuse block.

Strike that. See that you replaced it.

Re: Light, Turn Signal Issue
 

ray_mcavoy: My front and rear left signals work just fine. And my hazards work just fine too. It's the signal light in the instrument cluster that turns on when I turn the headlight switch on. But ya, I'll check all that tomorrow.

Thanks.

Re: Light, Turn Signal Issue
 

Okay, you can probably rule out bad grounds at the front & rear turn signal sockets then ... they usually cause problems with the turn signals & hazards too.

The turn indicator lights on the instrument panel are wired directly to the output of the turn signal switch that also feeds the outside front turn signals. So an incorrect bulb in the left front socket could still work okay for the turn/hazards but be be bridging to the parking light circuit and backfeeding power to the indicator light.

Finally, have you noticed any other strange behavior with the instrument panel when you turn the headlights on? If so, it could be a poor ground connection to the instrument panel. The printed circuit arrangement varies by year & cluster type, but many of these clusters have 2 or 3 ground terminals. And some clusters have the LH turn indicator sharing a ground connection with the cluster illumination lights. So a bad ground there could have the illumination circuit finding an alternative path to ground through the LH indicator bulb (causing it to light up when the lights are turned on). That type of problem usually affects at least some of the gauges though ... the ones that also share that same ground terminal.

Re: Light, Turn Signal Issue
 

I've got the full gauges (minus clock). All seem to work just fine. And it's an 84, all stock cluster.

Re: Light, Turn Signal Issue
 

I went out and looked at it again. I turn on the headlights, solid left blinker.

When I actually turn on the left blinker, then it blinks like normal. And hazards work fine, like I said before.

The gauge lights aren't very bright either, does that have to do with a dirty light switch?

Re: Light, Turn Signal Issue
 

What happens to the left front parking/turn signal light on the outside of the truck when you turn on the headlights? Does it light up at normal parking light brightness? Or is it brighter ... like turn signal brightness, just not flashing?

Is that with the headlights on or off? Or does that not make any difference?

Yes, that could be the problem (or at least part of it).

Also, does the brightness of that solid-on LH turn signal indicator change at all when you turn the headlight knob to dim the gauge lights?

Re: Light, Turn Signal Issue
 

I'll look tomorrow.

"Is that with the headlights on or off? Or does that not make any difference?"

Only with the headlights on.

"Also, does the brightness of that solid-on LH turn signal indicator change at all when you turn the headlight knob to dim the gauge lights?"

No change in the blinker light. But when I twist the light knob, the gauges don't dim or get brighter at all, they just shut off with the knob all the way clockwise.

Re: Light, Turn Signal Issue
 

make sure the cluster plug is in good and tight
paths can move /break or lift and
there are little nibs to line up the board at the marker sockets

Re: Light, Turn Signal Issue
 

The LH indicator light does not change brightness when I twist the headlight knob.

Re: Light, Turn Signal Issue
 

Visually check your bulbs. I had a Nova when I was in high school that did the same thing. Ended up being a front T/S bulb that the filament for the parking lights had broken loose and crossed over and stuck to the T/S filament. Worked perfectly with both systems. But with the lights on it would back feed the indicator in the IPC. Buddy

Re: Light, Turn Signal Issue
 

I just troubleshot this exact thing on my crew cab. I just finished replacing the gauges too so was unsure of where the problem was since I had to repin the connector on the gauges (thought maybe I screwed that up).

What you can do to eliminate the possibility of a light being the issue is go, in turn, to each light on the side whose blinker is staying solid, and remove the bulb. Then re-test the blinker and see if the problem goes away. If it does, then you know the problem is with that bulb (or socket!).

Turned out the problem was in the socket base for my front left turn signal. When that bulb was uninstalled, no problem. When it was in, the blinker would stay solid in the dash (but only when the headlights were on), just as you describe.

For me, the socket on that turn signal was/is going bad. If I twist it just the right way before installing it in the plastic signal housing, it works. Otherwise I have the same problem. Will probably pull a used socket soon and replace it.

Maybe not your exact problem but sounds close and easy to try...

Brian

Re: Light, Turn Signal Issue
 

I just went out and looked at it. With lights off, everything works fine. No light on dash, and all LH blinkers work as normal.

With full lights on (two clicks), the light comes on in the dash, but all blinkers work.

However, with just marker lights on (one click), the light still comes on solid in the dash, and all blinkers work, but when the blinkers are not on, the front LH marker light is out. Could that be it then?

Re: Light, Turn Signal Issue
 

Your getting warmer.

Re: Light, Turn Signal Issue
 

Is the left blinker slower when the headlights are on? Compare consecutively against the right blinker to be sure.

If so...yank that front left bulb and replace. If that don't fix it, look at the socket and nearby wiring.

Re: Light, Turn Signal Issue
 

No, they both seem to work at the same speed. I'll look at the socket tomorrow.

Re: Light, Turn Signal Issue
 

Well it could be in the back of the dash as well as others have mentioned. And make sure to look at the other lights...you never know which one it will be. The changed resistance in the socket caused the relay to blink that side slower in my case...so sounds like you have something a bit different.

The good thing about "troubleshooting" by replacing parts is that, in a light circuit, it is pretty cheap.