Vehicle is overcharging

AUSTINO

MEMBER
2003 JAGUAR S-TYPE
3.0L
6 CYL
2WD
AUTOMATIC
67,000 MILES

Good afternoon, my vehicle is overcharging. Do you know what can cause this to happen?Thank you in advance.

Sunday, June 28th, 2020 AT 10:07 AM

6 Replies

KASEKENNY

MECHANIC
18,907 POSTS

When you say it is overcharging, what is the actual voltage it is charging when the engine is running?

Take a look at this information. The ECM will target 14-15 volts and will back it down to 13.6 volts when needed. Let's start with what the voltage is and go from there. Thanks

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Sunday, June 28th, 2020 AT 4:49 PM

AUSTINO

MEMBER
199 POSTS

Thank you for that information. Yes, it is over charging when the engine is running and also the acid from the battery is leaking out.

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Monday, June 29th, 2020 AT 7:20 AM

KASEKENNY

MECHANIC
18,907 POSTS

Okay. Clearly we need to replace the battery but again, we need to find out the exact voltage it is charging. There is a chance that the PCM is trying to raise the voltage due to the battery so I would replace the battery due to the leaking and retest the alternator output.

Here is a guide on how to test the alternator:

https://www.2carpros.com/articles/how-to-check-a-car-alternator

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Monday, June 29th, 2020 AT 8:03 PM

AUSTINO