Chevrolet Repair Questions? Ask a Chevy Mechanic for Answers ASAP
Welcome I'm Chris aka Moose
The first thing I need is the year,make,and model?
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I am in my upper 30's, have a wife and 2 sons. I farm, fish, hunt, build, and coach youth soccer. I work on anything with an engine and have went to many schools and classes to get trained and certified. I try the best I can to share what I know and or have access to with my customers. Please consider I base my questions and answers to you, solely on the information you give me since I am not there to see, smell, hear, touch, or test. I try my best to be here everyday starting at 3pm central. Rating one of the answers, not the questions, you receive is required. Please let me know if your not pleased prior to rating so I can try to help a different way. God Bless and have a great day.
You may have not see what I wrote prior.
Is the coolant temp getting over halfway when the fan is then needed?
While running what is the battery voltage so I can see if the alternator is charging none or some?
Since you replaced the alternator then its fine. As long as the alternator gets battery voltage on the black wire and the other 2 wires ohm test good back to the ECM, then your charging system issue is due to a faulty ECM.
On the cooling fans, you have checked the fans and they work, so that means there ground is good. The ECT is reading so its good. That leaves the relays to check. Remove both fan relays, each should have 2 pins that are powered. If so then check the signal wire from the relays to the ECM to see if they are broken doing an OHM test. If the wires are fine then its your ECM to blame.
If wire diagrams are needed, let me know.
The HVAC blower is not related to the other issues. i was not aware it did not work. I thought the AC did not work, which is related t hte cooling fan not working and or the ECM.
The ECM controls the fan, signal to the start, and the alternator.
The ECM does not control the blower. The BCM controls the power to it and the HVAC control module and blower resistor control the ground.
Have a good night.