Tach Needle Thinks Its The Turn Signal

[JeffAARy]

My tach works, but when the turn signals go on the tach needle swings back and forth.  Is this a short somewhere or miswiring?  Originally this car, a 1971 Cuda, had a standard dash.  A previous owner put in a 1972+ rallye dash.  I haven't checked yet, but I think they brought over the rallye dash harness (has four dash illumination lights, although they could have spliced one in).

If its a problem with the circuit board, no problem - I'm upgrading to the rt-eng tach board anyway.

Ideas?

[vinb]

Maybe it could be the voltage limiter that plugs into the back of the cluster..

[JeffAARy]

That would be nice, as I'm upgrading that with an rt-eng version also.

[Swedefish]

Bad ground for the instrument panel?

[JeffAARy]

I don't think the entire panel is poorly grounded.  The gauges all work, as do the lights.

[71 DEPUTY]

I would say a bad ground too- it's the only thing they share. run a ground wire from the back of the metal dash to the dash frame.

[MEK-Dangerfield]

My only question is where he came up with a power source for the tach. if this is a standard harness. Maybe he tapped into something he shouldn't have?  This is a good one. Your tach is not the problem if it works fine otherwise. Wiring can be a bear to figure out after a bunch of owners have messed around before you.   


  Mike

[JeffAARy]

Yeah, miswiring of a standard harness is what I'm afraid of.  I was hoping this was a common problem and that someone would know right off the top of their head.  As usual with electrical problems it could be anything, or my personal favorite - multiple problems that cause misdiagnosis.