08 Silverado Voltage fluctuation

[rs74]

My father n laws 1500 started having this fluctuation issue here in the last week. I put a meter on it and it ranged from 13.2-14.8 volts. He drove it on a three hours trip and he said the the gauge was all over the place and also the other gauges and dash lights were doing different things. He replaced the battery since it was the factory one and just put a new alternator on it yesterday. Same problem this morning.

This truck has 80,000 on it and this is the first time it has happened. I have read that this is an issue with alot of these trucks but have not seen where there is a fix. Has anyone had this issue and resolved it? I have a call into the dealer ship as it has an extended warranty on it.

[rs74]

Any help would be appreciated.

[clinebarger]

The PCM turns On & Off the Alternator according to Amp Draw, You will notice a Amp Probe on the Negative Battery Cable. The Volt Gauge fluctuations are normal.

[rs74]

Is it supposed to make the other gauges fluctuate too? Why has it started doing this after not doing it for 80,000 miles?

[clinebarger]

Originally Posted by rs74

Is it supposed to make the other gauges fluctuate too? Why has it started doing this after not doing it for 80,000 miles?

No, But the Voltmeter fluctuation is normal, I have not ran across all the gauges acting weird, Without a GM Scan tool, These truck are hard to diagnose.