Turn signal comes on with dash lights

[Mike 71X]

Finished car up last year and drove it a couple months, no issues. Pulled the gauge cluster out over the winter to have some work done on a couple bad gauges and have the tach converted. In the meantime did not mess with anything on the car. Put the finished cluster in last night and now the passenger turn signal indicator in the cluster and the one on the hood both come on with the dash lights. With the dashlights off it works normally, hazards also; with the dash lights on the passenger side will still blink but much slower. First thought was I hooked something up wrong but I've gone through it and everything is in the right place. All connections are tight. Everything else works as expected, tach, new gauges. Second thought was the wire insulation is cracked on both the indicator wire and a dash light wire and they are touching. I don't believe that is the case. Wires to the headlight switch look good. Turn signal switch was replaced last year. Could it be the headlight switch itself? How about the flasher? I did drop the steering column down to get the cluster in and out. Could a wire from the signal switch be causing this? My next step is pull the cluster back out and see what happens.

 

[moparlore]

I just had the exact same problem recently. It was a sub-par ground at the marker light to the side which the dash light stays lit.

 

[Cranky]

Went through something similar when I pulled my cluster out to change out the bulbs. Laid it back in place to test and nothing worked right. Well, I didn't screw it back into place and once I did that, all the problems were gone. Grounds man....grounds!

 

[Mike 71X]

Checking the marker light grounds shortly. In the meantime I took the cluster out and same issue. The dash turn signal doesn't light since it's not grounded now but the hood indicator still comes on.

 

[jogirob]

+1 for grounds. From time to time my right turn signal indicator, when I turn my lights on, will stay on. I have to go out and fiddle with the mounting screw on the marker cover. Such a tiny surface area to rely on for your ground no wonder people suggest running separate ground wires straight to the bulbs.

 

[moparmarks]

Probably the ground at the front park lights. The screws ground the housing to the valance. Fresh paint it probably to blame. Real common on the 71/2 Plymouths.

 

[Mike 71X]

So I tried using a wire to ground the parking light on the suspect side to the crossmember. It worked, the indicators did not light up with the dash lights. I took the wire off, indicators back on. But now when I hook the wire up in exactly the same place the indicator light doesn't go out like it did the first time. Aaagh!
'

 

[moparmarks]

Sounds like your on the right track. You'll get it.

 

[Mike 71X]

Got it! Just kept running the screws in and out. Seems to be holding for now. Thanks for all the advice and what worked for me eveyrone. The rest of us would be sucking wind without you.

 

[moparmarks]

 

[hunt2elk]

Clean the area up good where the screw goes and put some electrical contact grease on before putting it back together.

 

[toolmanmike]

Was going to say bad ground before reading all the suggestions. I soldered a wire onto the outside of the socket and a eyelet on the other end to the radiator support. Bad ground fixed!

 

[72RoadrunnerGTX]

I’ve seen resistance between the socket sleeve and the turn signal housing on those as well. By ’72 there is a third terminal at the turn/park forward lighting harness connector that is grounded in the harness but not connected through to the turn/park lamp harness. Pretty easy to add a short ground run from the connector to the outside of the socket if not wanting to mess with any fresh paint.

 

[451Mopar]

Ground as mentioned. Those combination Marker Light / Turn Signal bulbs share a common ground, so if the ground is bad the Marker light grounds through the turn signal filament, back to the dash indicator light, and then the dash grounds the entire circuit.

 

[themechanic]

Thank God for this thread. I was about to give up troubleshooting until I read the posts above about grounding the front turn signals. So, I installed the front bumper and turn signal housings and the problem was solved.

Thanks FBBO!