High Voltage on Dash Guage

[kbuskill]

What was your gauge reading at the time you took the reading with the meter?

Is your volt meter on the dash fluctuating with RPMs?

When you measured the voltage after driving for 30 mins did you lay your hand on the alternator? Was it warm/hot like normal?

 

[Rocket Man]

You should go to an auto parts store and have them check the charging system. They have the equipment to check the alternator, regulator and battery and will do it for free. Maybe even go to two different ones just to be sure.

 

[Chuck_Finley]

I just got my Tahoe a few weeks ago and noticed this as well. I have a digital voltage readout from my ****** radar and when I start in cold temps (teens) it starts around 15v but drops to around 14 after a minute or so. The dash gauge matches what I see on the x50.

 

[PG01]

Mine sits in garage was cold but nit as cold as its been, I’ve seen my gauge at 13,14,15 .....normal. today for about 30 min it was high but was low again by the time I parked it, an hour and a half later. I have dual batteries in parallel and this is completely normal function of this charging system. On the neg cable off the battery there is a sensor to monitor voltage from battery, when its voltage is lower alternator charges when normal voltage alternator stops alternating (lol-joke) if you want, remove that sensor and youll get a more (i dont want to say accurate but...) normal-ish reading. It does no harm disconnecting this sensor.

 

[PG01]

Old post, my bad

 

[Rocket Man]

Old post, my bad

huh?

 

[Quag]

If it was me I'd change it out.

So changed out Alternator. Noticed VM on dash still high sometimes. Drove about an hour and half one way yesterday, VM just above 14 on the dash which on the DVOM has been about 14.1, but also never dropped below 14 like it has in the past. Ride back way above and checked when I got home and was 15-15.1. Never dropped. No rhyme or reason to it. Not throwing any codes, everything works fine. Battery seems to be at at about 12.8+volts (not sure of CCA) but starts fine. Really stuck on this and not sure if I should be worried. Shoot this is the only car I have that has a Voltage gauge on dash. Thoughts?

BTW still very cold temps. -8 in am. about 15 in the pm

 

[kbuskill]

So changed out Alternator. Noticed VM on dash still high sometimes. Drove about an hour and half one way yesterday, VM just above 14 on the dash which on the DVOM has been about 14.1, but also never dropped below 14 like it has in the past. Ride back way above and checked when I got home and was 15-15.1. Never dropped. No rhyme or reason to it. Not throwing any codes, everything works fine. Battery seems to be at at about 12.8+volts (not sure of CCA) but starts fine. Really stuck on this and not sure if I should be worried. Shoot this is the only car I have that has a Voltage gauge on dash. Thoughts?

BTW still very cold temps. -8 in am. about 15 in the pm

I wonder if the sensor that wraps around the negative battery cable is going bad and telling the ECM to charge more than necessary? Or perhaps the negative battery cable needs to be cleaned or replaced.... an internally corroded cable would cause higher resistance and possibly effect the sensors reading.

 

[Quag]

I wonder if the sensor that wraps around the negative battery cable is going bad and telling the ECM to charge more than necessary? Or perhaps the negative battery cable needs to be cleaned or replaced.... an internally corroded cable would cause higher resistance and possibly effect the sensors reading.

I will have to look into. Any chance the ECM is bad?

 

[kbuskill]

I will have to look into. Any chance the ECM is bad?

Anything is possible but I would rather try the cheaper parts first.