Instrument cluster turn signal troubleshooting

[HT413]

Need some help troubleshooting my turn signal indicators on the gauge cluster (69 belvedere). Pretty sure they've always been hooked up "sorta ok", but something's a bit wonky.

All this is with the key in the run position:

First, turn on the L or R blinker on, the correct turn signal indicator is blinking as you'd expect. But when I turn on the headlights (no blinkers), both turn signal indicators are continuous on. Pretty sure this isn't the way it's supposed to work.

Now with a blinker and parking lights, thw correct one blinks but slower and the other one stays continuous on. Turning on the headlights slows the blink more, high beams on makes it blink agonizingly slow.

Whatcha guys think?

 

[Shorthorse]

When things don't make sense, check your grounds.

 

[440+6]

How about the emergency flashers, I know it's a different circuit but if they work fine try swapping the flasher.
I'm curious so subscribed.
Make sure your cluster is grounded to the dash frame, I used a separate wire to make sure on mine.

 

[PurpleBeeper]

I'd have to check a wiring diagram.... but I think the emergency flasher & turn signal flasher are "sort of" wired together (uses same wire to deliver power after it leaves the dash/steering column. Since you get BOTH dash signal lights coming on, it "sounds" like it's an emergency flasher power feed problem, not a turn signal power feed problem (since both lights come on). Again, I'd have to check a wiring diagram, but I "think" the emergency flasher power feed gets its power from the headlight switch (& the turn signal power feed comes from the steering column I think).

All of your symptoms sound to me like there's a hot wire(s) crossed between your headlights & your emergency flasher power feed. The first place I'd check is the headlight switch itself OR the wires leading to it, especially where the wires go into the headlight switch plug. I have absolutely no idea why, but often when I have crossed wires, the bad/melted part is right near a connector/plug (could be just luck)

Oh yeah, and like these guys said...check your dash ground & column ground

 

[oldbee]

Ground check!!!!!

 

[HT413]

Thanks guys, ya gave me just what I needed - a good place to start.

 

[HT413]

I'd have to check a wiring diagram.... but I think the emergency flasher & turn signal flasher are "sort of" wired together (uses same wire to deliver power after it leaves the dash/steering column. Since you get BOTH dash signal lights coming on, it "sounds" like it's an emergency flasher power feed problem, not a turn signal power feed problem (since both lights come on). Again, I'd have to check a wiring diagram, but I "think" the emergency flasher power feed gets its power from the headlight switch (& the turn signal power feed comes from the steering column I think).

All of your symptoms sound to me like there's a hot wire(s) crossed between your headlights & your emergency flasher power feed. The first place I'd check is the headlight switch itself OR the wires leading to it, especially where the wires go into the headlight switch plug. I have absolutely no idea why, but often when I have crossed wires, the bad/melted part is right near a connector/plug (could be just luck)

Oh yeah, and like these guys said...check your dash ground & column ground

This makes a lot of sense. Thanks bro.

 

[SlinktRR]

my 70 b body wiring diagram shows that the emergency flashers and turn signals are wired adjacent to each other on the turn signal switch connector. I would start at that connector and trace wiring from there to the dimmer switch and flashers.

 

[HT413]

my 70 b body wiring diagram shows that the emergency flashers and turn signals are wired adjacent to each other on the turn signal switch connector. I would start at that connector and trace wiring from there to the dimmer switch and flashers.

Thanks, that's exactly where I'll start.

 

[HT413]

Well boys, think I figer'd it out. Disconnected the front turn signal lights the other day whiles I was taking my fiberglass bumper off for a repaint.

Yep, fiberglass bumper = nolo ground-o. Haven't put it back together yet, but I'm a hopin.

 

[1778ppr]

HT413,

As a check, try replacing your tail light bulbs or just remove them to see if the problem goes away. If one of the filaments in the dual filament bulb is touching the other it will act like what you are describing.

 

[ckessel]

Bad grounds at the lamp housings cause it to feedback. Need to correct.