03 Sierra Volt Meter Way High

[Turk]

Hi,

My volt meter is near pegging high and pegging high (past 19 volts).

Is the voltage regulator on an '03 GMC Sierra in the alternator??

Is it the voltage regulator?

Thanks!

 

[duaneb9729]

Check to see if your act getting high voltage at the battery, use a volt ohm meter and set it to dc volts while your truck is running and measure the voltage at the battery terminals.

I believe the voltage regulator is built into the alternator

 

[JHZR2]

+1 check that fast with a multimeter. You will destroy you rbatry and risk an explosion of it from overcharging that high... let alone the rest of the electronics in your truck. My guess is a bad ground of some sort screwed up the gauge reading.

 

[eljefino]

Run the blower motor and headlights, are they faster and brighter than normal? Blower motor is a great tool as the varying pitch can easily be picked up by your ears.

You should be getting ABS, AIRBAG, and CEL lights if your system voltage is really that screwy. Alt MIGHT be BCM controlled.

 

[Turk]

Wow. I am getting no lights, codes or messages whatsoever.

Lights look a little bright, but not like one would think...

^ said, don't know if I wanna check the voltage at the battery if it may explode!!!

Thoughts?

 

[defektes]

Use a face shield, long sleeve work shirt and gloves. And get'er done! Check the voltage.

 

[eljefino]

If you ran at 19v the battery would show recent activity, eg dust near the vents might be wet with burpy acid.

You can get voltage readings at the trailer wire connector with parking lights on if you want some distance between yourself and the acid bomb.

 

[JHZR2]

Yeah I was going to say to pull the voltage at the cigarette lighter plug. if it is less than 19V or the red area on the voltmeter on the dash, then Id go investigate on the battery itself.

 

[Turk]

Called the dealer and they said there's a lot of faulty gauges, so the volt meter will prove that out or not...

 

[Turk]

Ok, here's the follow up.....

Hooked up my engine analyzer, aimed the display to the cab & started it up. Went to 14.3 volts - so it's the instrument cluster as the dealer thought!

 

[mechtech2]

Right.
Recheck with a good gauge.
If still high, you need a regulator. I hope you are not governed by the computer - some cars are!