Generator Voltage Sensor High?

[Corkey]

So I got my truck new rear calipers, pads, and rotors for the rear.

MM3 shows 14.9v max after start-up, then 14.6v at idle.

Guage cluster voltage shows 9v or maybe 10v.

20-mile drive home.

It didn't change and seemed to reset max settings as the MM3 lost proper voltage to communicate with the ECM.

Any idea what to check?

Put a tester on both batteries, still hooked up, and read 14.6 at idle.

Batteries are maybe four months old.

Yes, I'll get it load tested tomorrow, but I ran into this issue roughly four months ago, LOL, and replaced the batteries, and I'm experiencing the same problem.

Edit: P063D

Even with the key off, I heard a high pitch sound from the speakers.

My switch for the train horn was tapped to the fuse #36 "audio amplifier."

The train horn is also wired to a constant hot; it might have been a draw to weaken the batteries.

KOEO 12.5V on the alternator, clear codes 3x, and no luck.

Test lite all fuses check out good; test lite grid heater engine on with no light, so grid heater works properly.

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[AK Bob]

Have you run through the troubleshooting steps for the P063D trouble code attached?

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[Corkey]

I tested the voltage on the cross-over cable to the positive terminal and only got 1v.

Measured from the cross-over connector to the cable just before the clamp, it got 13V.

The moral of the story is if it looks clean, still remove other accessories and clean; this was my issue.

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[AK Bob]

I tested the voltage on the cross-over cable to the positive terminal and only got 1v.

Measured from the cross-over connector to the cable just before the clamp, it got 13V.

The moral of the story is if it looks clean, still remove other accessories and clean; this was my issue.

Good work; pleased to hear you got her fixed.

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