TAC Tech > Electrical

Dash lights mess up my gauges - The I.P. Ground Story

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firebirdparts:
We used to have a sticky on this, and so here is the replacement.

The IP Ground on a Trans Am is to the dash frame to the driver's left, the short side.  The dash is plastic, so this frame is only grounded if the dash is bolted in.  There's supposed to be a bolt on each end of this frame.  If you are working on the dash, you are likely to remove the dash brace and you could lose ground of the other end, at the door, was loose.



The dash lights and the gauges are both grounded through this same path. If there is any resistance in this ground path, the lights will tend to put voltage on this circuit and the gauges will be affected.

chief poncho:
Great sticky!  The IP isn't the best grounded.  I may run a ground strap to the chassis.

pozarcar:
I installed a new dash gauge circuit "board".  When I got the gauge cluster reinstalled (bezel still off) and hooked up the battery, I got the "magic smoke" and discovered that the circuit to the ground pin on the dash harness plug (top left pin - black wire - on my 78) had melted. Would it be a bad IP ground that would cause this?

I had also converted my clock to quartz movement and reinstalled it.  Not sure I got the clock power wire put back right.  Is there a nut on the threaded end of the red power wire that goes inside the metal cluster housing, and then another nut on the outside securing the printed circuit, clock power wire and cluster housing all together?

Wallington:
Sounds like an insulating washer or sleeve missing somewhere, live and grounding coming together . Any pics? Possibly pulled the gauges apart by now, also check the circuit board sheet, they have a habit of being the first to burn or mark since so flimsy, but this sounds more direct in the fixtures. Still 1978 style set? Wouldn't expect a missing earth would matter, it's just an extra. More the opposite.

b_hill_86:
I’d think your clock conversion might be something to do with it. First I’d double check your new printed circuit against the old print circuit just to make sure they’re identical, and that you got the correct one but beyond that the only thing I can think of that would get battery power rather than ignition power is the clock. Did your cluster have the electromechanical clock that you replaced with quartz conversion? I’m going from memory, but no, I don’t believe there is another nut on that positive post for the clock, except the one on the exterior of the assembly.

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