1990 Mustang LX ground wire - Ford Mustang Forum

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post #1 of 4 (permalink) Old 04-07-2012 Thread Starter
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1990 Mustang LX ground wire

When I sit at a redlight, my voltage gauge drops way down. I have conclauded that this is most likely a ground issue because I have changed the alternator, battery cables, and had the battery checked. I was checking the ground behind the radio and found a black wire and a red wire, both both bolted to the bracket above the radio. I noticed that they sparked when they bumped together, checked them and the red wire has almost 11 volts on it. Any ideas on what this wire is or why it would have a voltage on it?

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post #2 of 4 (permalink) Old 04-08-2012 Thread Starter
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ground wire update

Update: I reconnected the black wire and cranked the car. Everything seems to work as usual, but the radio doesnt have power.

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post #3 of 4 (permalink) Old 04-08-2012
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The EVTM says

CONDITION: Radio does not work

No voltage at Y/BK wire of Radio ...or.... Radio not grounded

ACTION: Check Fuse 11 and wiring ...or.... Check R wire for opens from Radio

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post #4 of 4 (permalink) Old 04-08-2012
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If the red wire was grounded and radio worked it probably needs to be grounded for the radio to work even though its red.Possibly someone spliced a red wire to a ground wire for radio.The spark and voltage to ground reading you got is normal if the radio has a + 12 volts feeding it on another wire and the red wire is a ground for radio.You may have to trace wire and color codes down to verify what they are and how to connect them properly.
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ground wire , voltage drop

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