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Ron, ASE Certified Technician
Category: Chevy
Satisfied Customers: 35497
Experience:  35 years experience with ASE Certs
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2002 suburban - battery light coming on intermittently. new

Customer Question

2002 suburban - battery light coming on intermittently. new battery. alternator tested good. Looked at fuses. Still happening. What can I check next?
JA: Have you tested the battery? Have you tried testing the alternator?
Customer: new battery, alternator tested good
JA: Are you fixing your Suburban yourself? What have you tried so far?
Customer: I just wrote what I have tried.
JA: Anything else you want the mechanic to know before I connect you?
Customer: no
Submitted: 6 months ago.
Category: Chevy
Customer: replied 6 months ago.
I have replaced the battery with a new one. I have had the alternator tested and it is charging fine. I have thought of looking at fuses, but usually they are either good or bad. It acts like there is a short. I just don't know where it would be.
Expert:  Ron replied 6 months ago.

Hello. My name is ***** ***** I am happy to assist you today. Give me just a moment to review your post, and I'll be right back with the help you need.

Expert:  Ron replied 6 months ago.

Have you scanned the computer system to see if there is any fault codes setting, in most cases if the battery light is coming on there should be .

Customer: replied 6 months ago.
No, I don't have a scanner. But, someone online having the same problem said they were getting P1638.
Expert:  Ron replied 6 months ago.

If in fact you are getting a fault code P1638 then in most cases this codes sets due to a bad alternator. This code can set and the battery light will come on even when the alternator is charging. I would suspect that is what you have going on here.

Customer: replied 6 months ago.
the person online replaced the battery and the alternator and was still having the same problem intermittently. What then?
Expert:  Ron replied 6 months ago.

Im not sure about the person on line but the light will not come on due to a bad battery, the charging rate and battery light are controlled by the duty cycle from the PCM (computer) to the alternator internal regulator. Before you replace anything you really do need to start with having the computer system scanned to see what the fault code is that yours is setting.

Customer: replied 6 months ago.
I am not interested in a $400 try and see. What else could it be?
Customer: replied 6 months ago.
Okay, I guess I should go have the codes checked. Thanks.
Expert:  Ron replied 6 months ago.

That would be the next correct step for you. Once you have it let me know and we can work from there.