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Ask Jared D Your Own Question
Jared D
Jared D, ASE Certified Technician
Category: Chevy
Satisfied Customers: 1858
Experience:  Shop Supervisor at County Fleet
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Alternetor starts to charge then stops after 10 sec. New

Customer Question

Alternetor starts to charge then stops after 10 sec. New alt. new battery. what is voltage that is suppose to be going to ecm from alternator?
JA: Will the headlights turn on? Is the battery fully charged?
Customer: Yes when we first start, Batt at 100%
JA: What is the model of your '10 Chevy?
Customer: 2001 olds silhouette
JA: Are you fixing your Silhouette yourself? What have you tried so far?
Customer: All DIY had new Alternator tested had new batt installed checked all fuses.
JA: Anything else you want the mechanic to know before I connect you?
Customer: No. I want to know what voltage should be from Alternator to ecm ?
Submitted: 1 year ago.
Category: Chevy
Expert:  Jared D replied 1 year ago.

Check for B+ on the Orange wire at the connector to the alternator. Verify the PCM is sending out 5 volts on the Red wire at the alternator.

Expert:  Jared D replied 1 year ago.

We have seen a lot of alternators with the wrong regulators installed in them which will not turn on with the 5 volts that the PCM puts out. If you get multiple alternators that don't work, try a different supplier. Sometimes AC delco is the only option.

Expert:  Jared D replied 1 year ago.


Thank you for the opportunity. I love helping people fix their cars and saving them money. Please keep in mind that most problems will require some diagnosis to get them sorted out. I will be here to help until you are satisfied.

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Customer: replied 1 year ago.
red wire has 5volts for a short time then drops out. Does 5 volts come from PCM or alternator ?
Expert:  Jared D replied 1 year ago.

5 volts comes from the PCM. If it's dropping out then the PCM might be faulty.

Expert:  Jared D replied 11 months ago.

Let me know if you still need help with this.

Please don't forget to rate.