Instrument lighting issues

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matt030305

matt030305

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when I pulled out the gauge clusters to lube up a speedo cable in my 70 duster and reassembled it. I tested everything to make sure I was working but to my surprise, the instrument lights were all wonky (see first photo attached). I tried dimming the lights but they only went back to how they were supposed to once I turned on the dome light (see second picture) any idea why this could be happening? Thanks for the help!

IMG_4830.jpeg


IMG_4832.jpeg
 
What year car did the gauge and speedometer cluster come out of?
 
If you did this test without the cluster installed (with screws!) in the dashboard, you'll get all kinds of wonky electrical paths like this because the whole cluster gets its ground by the mount screws pressing it hard against the metal dashboard. If you want to test it uninstalled, you have to run a ground lead from one of the bare copper ground points surrounding the mount screw holes.

If this is with the cluster installed, well…shee-yit!
 
slantsixdan said:
If you did this test without the cluster installed (with screws!) in the dashboard, you'll get all kinds of wonky electrical paths like this because the whole cluster gets its ground by the mount screws pressing it hard against the metal dashboard. If you want to test it uninstalled, you have to run a ground lead from one of the bare copper ground points surrounding the mount screw holes.

If this is with the cluster installed, well…shee-yit!
Click to expand...
Ohhhhh this makes so much more sense now that I’m thinking about it. I’m always having electrical (ground issues haha) thank you very much
 
ALWAYS add a grounding pigtail from a point on the cluster to the column support or dash frame. The original screws / grounding can be a little, "rusty" after these years
 
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