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rpmdiag, Tech and Instructor
Category: Pontiac
Satisfied Customers: 8068
Experience:  Since 1975
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I have a 2005 ponntiac montana SV6 3.5L with 125A

Customer Question

Hi Pearl, I have a 2005 ponntiac montana SV6 3.5L with 125A alternator. Shortly after startup the battery light comes on. Between startup and light on it is charging. 14..4v. When the light comes on charging voltage drops to 12.2. Any ideas? Thanks Randy
JA: Lots of things can cause problems with the battery. The Pontiac Mechanic will know what to do. Are you hoping to fix this yourself?
Customer: Yes. I am a retired ASE.mechanic a little out of touch with today's technology soooo....would like too fix it myself
JA: Great! What have you tried so far?
Customer: Battery load test, alternator output test, connector "wiggle" test, checked all fuses/relays, checked all ground connections,. It acts like a relay kicks out when the light comes on
JA: Is there anything else the Pontiac Mechanic should be aware of about your Pontiac?
Customer: No other recent repairs or electrical work. Its my wife's vehicle and she reports no unusual events when it happened the first time
JA: I'm sending you to a secure page on JustAnswer so you can place the $5 fully refundable deposit now. While you're filling out that form, I'll tell the Pontiac Mechanic about your situation and connect you two.
Submitted: 1 year ago.
Category: Pontiac
Expert:  rpmdiag replied 1 year ago.

Hi, I’m Ron and I can help you.
I have been in this business since 1975 and also teach automotive repair. I am confident
we can resolve your problem together. Please understand that I don't know your skill
level. I can't see, smell, hear, or touch the vehicle either, so it may take a few replies to
get to satisfactory results. Please be patient!
I also try to give all of the information you may need, expecting a “positive rating” in
return. I will also continue assisting you after you have rated me, if necessary. If there
is any reason I cannot get a positive rating, please let me know why “in advance”, so I
can go another direction for you. I am sorry you’re having this problem; I’ll help you
through it.
If the battery tests good, then the alternator needs to be full fielded with a machine capable of doing this. If this all works, then there may be a malfunction with the computer and that needs to be tested with a scan tool in bidirectional mode.

Thanks, Ron

Customer: replied 1 year ago.
I know the alternator is good. It puts out 14.4 until the light comes on. I have access to a tech 2. If need be
Expert:  rpmdiag replied 1 year ago.

Got it, let's see what the tech 2 says now.

Thanks again, and please don't forget to rate me and keep this link in case you need me again later on.