Hi all, looking to see if anybody has been here with a charge light issue on a 2.5T?
It's a 2006 2.5T Titanium. Got bumped very lightly last year but there were issues with the insurance and it ended up being parked up for ages, unused. Battery went flat in this period, but recharged and seemed to hold it.

Since it was parked, the charge light came on. It wasn't immediately after the bump, so I don't believe that to be related (it was a parking ding, anyway).
 

 

 Fault code given is P2502 - Charging System Voltage

Upon starting engine, light doesn't show for 30secs or so. In that time, the voltages seen by the PCM do not change, even when the light comes on. My guess is it's doing some kind of check and when it decides its not happy, it throws the light on.

Alternator was tested as dishing out 13.8v, despite the lamp being on. I renewed the alternator because I figured it was still possible the alt wasn't relaying the charge status back to the PCM (and I was out of ideas, otherwise).

New alternator didn't make a difference.

New battery fitted as I figured one or two cells might have died, and it was a few years old anyway. No difference (other than cranking voltages being better than they were).

Main earth terminal on body near battery is good.

Small connector to alternator shows 4v with ignition on - not sure what it's supposed to show.

Large cable connection is good. No corrosion.

With small connector unplugged, symptoms are exactly the same with exactly the same as above & with fault codes. The car behaves no differently whether the connector is plugged in, or not.

I'm guessing it's either PCM itself, or some kind of wiring fault. Are there any common areas to check?

Thanks

2 hours ago, kitch29 said:

With small connector unplugged, symptoms are exactly the same with exactly the same as above & with fault codes. The car behaves no differently whether the connector is plugged in, or not.

It is common for the wires in the small connector to break or corrode.

The voltage 13.6 to 13.8 is the alternator default output when the control and feedback circuit is not working. I doubt the issue is with the PCM it is far more likely to be a broken connection with the small connector.

1 hour ago, unofix said:

It is common for the wires in the small connector to break or corrode.

The voltage 13.6 to 13.8 is the alternator default output when the control and feedback circuit is not working. I doubt the issue is with the PCM it is far more likely to be a broken connection with the small connector.

Thanks, I've read that elsewhere too.

The plug looks absolutely fine externally, but I guess I'll have to dig around inside to eliminate it from the search. Someone else suggested finding the pin on the PCM that the feedback wire goes to and running a seperate lead to see if the fault lies in the wiring loom elsewhere. Can't find a pinout diagram for the PCM, though!

Did you find the problem?

I have the same problem.

Thanks