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volt guage says 11.8-12.4 scan guage says 14-14.2

Either at highway speed or idle my voltage guage in the dash says 11.8 to 12.4 volts and my scan guage says 14 - 14.2 when this low voltage happens. So far nothing seems to be affected by this. I guess it might be a bad ground wire to the cab but that's just a guess. Does anyone have any advice or experienced this before. The truck is a 2003 freightliner Columbia with a Detroit 12.7

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I lost all my guages and power to the cab yesterday, so I stopped at a shop at Louisiana i20 x 8 next to the petro, they load test the batteries and found 2 dead changed those and in changing the batteries the mechanic realized that the battery cable had been broken where the ecm wire connects to the battery cable. Every thing is good again. The best thing is the shop took about 20 minutes to finish this.


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put a volt meter to the alternator and you'll know which gauge is not reading accurately.

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It's always good to remove the ground wires to the frame and sand the frame and the lug for good contact. I would also run a ground wire from the alternator to the frame, from the alternator to the starter and from the starter to the frame. You can never have enough ground straps........

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Nick will be eternally grateful.
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