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sean
sean, Ford Technician
Category: Ford
Satisfied Customers: 3105
Experience:  Ford Master Technician.
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I had a new alternator fitted to my 2001 Mondeo Mk3, petrol

Resolved Question:

I had a new alternator fitted to my 2001 Mondeo Mk3, petrol engine, the battery light stays on. The volts at the battery, engine not running 12.6volts, with engine running 14.7v.
The alternator is delivering the notional correct voltage, but why is the battery light on continuously? Your advice would be appreciated.
Bill Sheils
Submitted: 2 years ago.
Category: Ford
Expert:  sean replied 2 years ago.
Hello, I hope the following assists you.
The charging system on this model is a "smart charge" system where the charge rate is controlled by the engine management (PCM) and it is the PCM that instructs the cluster to illuminate the warning light when a fault is detected.
The most common cause given that a new alternator has been fitted is a smart charge circuit fault.
The small connector on the alternator should have a 12 volt supply at pin 1, this is fed by fuse 30 in the fuse box under the bonnet so check for 12 volts at pin 1 and double check the fuse of it's not there.
If the 12 volt supply is OK then the wiring between the alternator pins 2 and 3 and the PCM pins 72 and 59.
It's not uncommon for the wiring to become damaged then corrode in the engine bay close to the alternator.
If there is a smart charge fault the alternator will revert to a fixed charge rate rather than the charge varying to account for electrical consumers switching on and off.
I hope this helps but if I can provide further information let me know and I'll reply as soon as I'm able to.
Best wishes,
Sean.
sean and other Ford Specialists are ready to help you
Customer: replied 2 years ago.

Where is the PCM located.

Bill Sheils.

Expert:  sean replied 2 years ago.
Hello again,
the PCM is located on the right hand side of the engine bay, you'll see the wiring going to it just behind the suspension strut housing, there may be a riveted security shield over the connector.
Let me know if I can assists further.
Best wishes,
Sean.