Variable Voltage

[BuffettTruck]

I have an 05 Tahor Z71 2WD. I am chasing an amperage issue within my electrical system. I replaced the alternator and battery last November ('19) and had to replace them again in March.

My question regards the fact that the voltage in the dash cluster will fluctuate from 12.4 to 14.4. Using an OBD reader and Torque as well as another digital voltage display, I have seen the same fluctuations.

I know GM started using Variable Voltage in their trucks and SUVs, but I can't find info on when they started using it or if the '05 Tahoe had it.

Any one have any insights? Thanks.

 

[Mooseman]

At some point, they started adding SARVC to the charging system. On 360's, it was around 2006. Don't know about full size trucks though. Check on the negative battery cable for a module attached to it with a loop around the cable.

 

[TJBaker57]

My 2005 Yukon 5.3 LM7 has this system.

 

[TJBaker57]

Do you have this sort of device on your Tahoe???

 

[BuffettTruck]

I do have that sensor. So I guess I have it. Thanks.

 

[Mooseman]

To see if that's what's acting up, unplug it. The alternator will work as a regular one and not drop the voltage over time like it does with it active. It's designed to lower voltage once the battery is fully charged and power demands are low. It shouldn't fluctuate continuously but slowly drift down to about 13V. If power demands increase (i.e. you turn on A/C), it will bring it back up. It's to help the battery last longer.

 

[TJBaker57]

I have had fluctuations that I believe we're caused by poor battery connections. It caused my headlights to flicker quite noticeably.