Battery Jumped backwards?

2005 FORD TAURUS

300,000 MILES • 0.6L • 6 CYL • 4WD • AUTOMATIC

SILK ROSE

MEMBER
1 POST

Hello my name is Jae. My boyfriend hooked the battery cables backwards. Long story short. I have replaced alternator (brand new) and battery. I am still getting a check charging system code with the battery icon lit. I also have replaced battery cables. Any thoughts or advice?

Jun 15, 2017 at 9:38 AM

KASEKENNY

✓ASE Certified Mechanic
18,907 POSTS

This could be a couple things so we need to find out what codes are there to start.

https://www.2carpros.com/articles/checking-a-service-engine-soon-or-check-engine-light-on-or-flashing

If there are no codes then we need to find out if the PCM is getting the correct voltage signal from the generator.

https://www.2carpros.com/articles/how-a-car-electrical-system-works

The way this works is it gets the voltage and then the PCM sends the info to the cluster to turn the light on or off.

If the PCM is getting the proper voltage on the generator sense wires then the PCM is the issue. I suspect what is happening is the PCM has a circuit issue and is incorrectly turning on the lamp. So if the PCM is getting the proper voltage then it is a PCM.

https://www.2carpros.com/articles/how-to-check-wiring

Please see the wiring diagram below for the info on this. Thanks

Image (Click to enlarge)

Professional Diagram for 2CarPros Members
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Jun 9, 2021 at 2:57 PM

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