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17:26:43 - 04/26/2024
V6 Dakotas
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geo.
Dodge Dakota
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7/29/2009
08:25:27
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 Subject: draining batt. 92 3.9
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Message:
have a 125 Ma draw on batt 24/7. batt goes down in 3-4 days if not driven. batt is new & just woundering where that current is going. has always been this way, nothing new. can live with it but i let it set for days with out useing it & have to jump it off or put charger on, gets to be a pain. all help app.
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Bob Lincoln
Dodge Dakota
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7/29/2009
08:44:21
|  RE: draining batt. 92 3.9
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Message:
I can tell you *exactly* what this is, since I had it myself on my 92 Dakota. The tachometer drive board, which is a small circuit board that plugs into the instrument panel board, draws over 100 ma BY DESIGN. I am an electrical engineer and traced out the circuit. It always has battery power to the tach board, which is unnecessary, and a transistor is always on that feeds current through a Zener diode to ground.
I fixed it by cutting the circuit trace that goes to the battery and using a jumper wire from there to the circuit trace that's powered by the ignition (the board gets both ignition and battery power). This only allows power to the tach with ignition on, and it performs the same. If I get a chance, I'll post which pins on the board have ignition and battery power.
This is not a failure, it's by design, and my brother went through several batteries when he owned the truck (since new), never knowing what was wrong. The dealers never could figure it out.
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