I've had the battery light on for the last 2 days. I've had no problems cranking or running, but occasionally it's not enough to power the UltraGauge through the ODB port. When the UG and the Battery light have been on together, I've noticed UG Volts were at 11.2-4 and when its the battery light goes away UG Volts is around 13.5. The light isn't flickering and the behavior seems to change with each crank. I drive to the store with the battery light and no UG. When I leave the store its running fine.

Any thoughts? I understand the Battery light will come when alternator volts are less than battery volts, but why would it be changing?

 

 

Robert, if you don't have a battery charger that can test the alternator and battery take the truck to any major auto parts chain store. They have diagnostic tools appropriate to your needs that they will use at no cost to you to diagnose your truck's problem.

 

Sounds like the indication is working as advertised, likely the alt voltage regulator is intermittently going TU and is going to hard fail soon. You may want to check all your connections and grounds. I see a alternator replacement in your future
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Clean and check all of your terminal ends...especially ground at engine bracket. If still shows low charging numbers, have alternator checked.

Brian.

 

Just wanted to float an idea out there. Sometimes I go back to look and my problem posts and I see a problem emerge. So I'm starting to develop a theory.

A few months back I was cleaning up after a coolant leak and I noticed the AC compressor bearing blew out a bunch of dust and started squeaking. I've had it on my to do list for a while. Then about a week ago I noticed some slightly warmer temps than normal for no apparent reason. Now my alternator looks to be failing.

Could it be that the AC bearing is causing belt issues which is adding resistance and affecting my water pump/fan and is now slowing down the alternator causing charging problems? It's hard for me to tell just by looking.

 

Take the belt off.
AC pulley should spin freely, since it has a clutch to engage it.
The belt will slip though if the compressor bearing is starting to sieze, as the ac compressor can't slow down the engine or idle speed.

 

I took the belth off, the AC pulley spins freely but there is definitely bearing noise. I'm not sure if spinning at speed/heat would more likely induce seizure. Are you saying that even if it seized the belt would slip through and operate as normal? I would think that a slipping belt could have serious problems?

I'm trying to decide if I should replace the AC bearing first and see if that resolves the issue. Or if that would be a non-issue then I would jump straight to the alternator and replace the AC bearing later this month to get ride of the squeaking.

 

If the compressor locked up, the belt would slip for a short period of time, then break.

 

Check all your other pulley/idler bearing as well? Also check to ensure your tensioner is strong and free to do it's job, if limp it could cause a slower alt rpm.

Can't rule out the AC clutch bearing and you really should address it sooner than later. It could be dragging more than you think with the belt and a load on it and you never know when it might seize.
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