Help! Just replaced alternator & batt light still flickers. What next???

[RenaissanceMan]

Hey everyone-

For the last several weeks my battery light has flickered for about 2-5 seconds after starting the X5. The light always goes away after several seconds and the truck has run fine. It has always started right up without hesitation, and the battery never drained. The only other symptom was that my PDC would mysteriously turn itself on as soon as I cranked the engine (usually preceeded by a PDC light flicker for a couple of seconds). Unlocking the OBC revealed that I was holding a steady 13.9-14.1 volts while running. Did a lot of thread research here and got some helpful advice along the way... It was suggested that some component(s) inside the alternator was going South, so I decided to just replace the entire alternator.

Anyhoo, replaced the alternator today along with the belts & oil stand gasket, and when I went to start the truck, lo and behold I had the same exact symptoms as before: Flickering battery light for a few seconds immediately after cranking, and then it goes away. Still showing steady 13.9-14.1 volts. I'm assuming I didn't purchase an alternator with an identical malfunction, so now I'm thinking maybe the alternator was never bad in the first place.

Is there any possibility that my battery, even though it is holding charge and starting the truck w/o problem, could be doing something to cause this strange behavior??? I was going replace the battery next but wanted to ask the experts first. At a total loss here so any help is greatly appreciated! Thanks for reading!

[SlickGT1]

How old is the battery. Battery light usually means battery

[RenaissanceMan]

Originally Posted by SlickGT1

How old is the battery. Battery light usually means battery

2 years old IIRC.

[TwinTurboGTR]

Doesn't battery light indicate a fault with the charging system? Not just the battery? In any case, battery at that age should still be good.

[Qsilver7]

Originally Posted by SlickGT1

... Battery light usually means battery...

I have to kind of disagree with ya on this one....just a little. The battery light is usually an indication/warning that the battery is the VICTIM of the alternator/charging system...not the CULPRIT.

If the warning is ignored and the alternator/charging system goes unchecked...then eventually the battery can become the culprit...but that's only after its reserve capacity has been drained to the point of death...and after repeated deep discharges...never being completely recharged by the alternator/charging system...it succumbs to an untimely death.

I put this warning light on the list of most misunderstood warning lights.

Originally Posted by RenMan

I was going replace the battery next but wanted to ask the experts first. At a total loss here so any help is greatly appreciated! Thanks for reading!

At this point, I'd hold off on spending money on a new battery...especially since you've unlocked the OBC and can monitor both the battery (ignition in position 1 or 2 & engine NOT running)...and the alternator/charging system (engine running)...and get a glimpse into the functioning of those components & system.

Make sure you've checked your belts, tensioners, & pulleys, too...if the are loose and/or failing or slipping at start up...they could be causing the momentary flicker at start up.

[RenaissanceMan]

Originally Posted by Qsilver7

At this point, I'd hold off on spending money on a new battery...especially since you've unlocked the OBC and can monitor both the battery (ignition in position 1 or 2 & engine NOT running)...and the alternator/charging system (engine running)...and get a glimpse into the functioning of those components & system.

Make sure you've checked your belts, tensioners, & pulleys, too...if the are loose and/or failing or slipping at start up...they could be causing the momentary flicker at start up.

Thanks for the feedback!

I'm guess I'm going to go and get the battery tested next and see what comes up. (EDIT: Is a test from Autozone, etc going to be accurate enough?) As for belts, I just changed them when I did the alternator. I'm not hearing any squealing or 'chirping' from the tensioners or pulleys... When I had everything taken apart, all pulleys turned freely by hand. I'm not sure how to know if a tensioner is bad...? If tensioner, belts, and pulleys seem to be working correctly, what the heck else could it be? Thanks again everyone for the help!

[upallnight]

Originally Posted by RenaissanceMan

Thanks for the feedback!

I'm guess I'm going to go and get the battery tested next and see what comes up. (EDIT: Is a test from Autozone, etc going to be accurate enough?) As for belts, I just changed them when I did the alternator. I'm not hearing any squealing or 'chirping' from the tensioners or pulleys... When I had everything taken apart, all pulleys turned freely by hand. I'm not sure how to know if a tensioner is bad...? If tensioner, belts, and pulleys seem to be working correctly, what the heck else could it be? Thanks again everyone for the help!

Battery should be fully charged before you take it to Autozone and have them perform a "LOAD" test, not just a volt meter test that only indicate the voltage on the battery.

[SlickGT1]

Originally Posted by Qsilver7

I have to kind of disagree with ya on this one....just a little. The battery light is usually an indication/warning that the battery is the VICTIM of the alternator/charging system...not the CULPRIT.

If the warning is ignored and the alternator/charging system goes unchecked...then eventually the battery can become the culprit...but that's only after its reserve capacity has been drained to the point of death...and after repeated deep discharges...never being completely recharged by the alternator/charging system...it succumbs to an untimely death.

I put this warning light on the list of most misunderstood warning lights.

At this point, I'd hold off on spending money on a new battery...especially since you've unlocked the OBC and can monitor both the battery (ignition in position 1 or 2 & engine NOT running)...and the alternator/charging system (engine running)...and get a glimpse into the functioning of those components & system.

Make sure you've checked your belts, tensioners, & pulleys, too...if the are loose and/or failing or slipping at start up...they could be causing the momentary flicker at start up.

I agree with you, only one issue. I just replaced my voltage regulator. Inpa was recording undervoltage and overvoltage on every trip. Not even once did the bat light flicker, not even a flash. Yes I tested that it works.

So I only speak from experience, even though the literature you have is spot on.

[RenaissanceMan]

Folks, quick question. What should the battery voltage read prior to starting the X5? Mine is showing 11.6-11.7 volts. Is that considered 'low' or 'normal?' Going to head to Autozone in the morning for a load test.

[SlickGT1]

Normal, at least fine