Hi does any one know how to reset the fault on the dash of my p38 4.6 hse 98 plate. after fitting a new alternator the fault code flashes up everytime i start it any ideas?????

The instrument cluster has no fault memory it just reports hard faults, Meaning if you fix the fault the message will clear.

Did you change the alternator because your dash reported it as a fault or was it physically not charging?

Once the Alternator produces charge it sends voltage to pin 15 plug C114 and the becm puts the Charge warning light out.

Pin 15 on plug C114 (early >1999) or C1289 (late 1999>) Is the Alternator charge input to the becm . It is a Brown and yellow wire. The Plug is the largest green plug on the Becm, behind the cowling underneath the front of the driver’s seat.

If this wire fails then the charge light remains on and the instrument cluster reports alternator fault even though the alternator is charging perfectly.


Petrol P38: The wire runs from the alternator to connector 106 pin 3 of a 13 pin plug which is underneath the coolant expansion bottle.
Diesel P38: The wire runs from the Alternator to connector 121 pin 25 of a 25 pin round connector which again is underneath the coolant expansion bottle.

Both plugs suffer from green pins being directly underneath the coolant bottle.

Thanks for response he changed the alternator because the bearings where noisy but it was still charging, but i will get him to check the connector under the coolant bottle and let you know thanks again.

No Problem, good luck.

Hello me again sorry to report the idea didnt work he unpluged the connector under the washer bottle and cleaned all conectors then re fited to hear the same warning on starting the vehicle. It was as good try thanks Russ.

Was the battery voltage actualy checked at the Becm plug?

Are you 100% sure that the alternator is good? I had an alternator refurbished by a well respected company and after fitting it the lights started "Pulsing"-checked the output voltage and was surging from 13 to 20 volts-would do all the ECU's the world of good no doubt.

Thanks for response he has noticed a noise from the alternator which is still under waranty so he is replacing it this afternoon so i will let you know the out come.

Hi all from Hong Kong. I have used this forum for help on some elec. probs on a customers 98 4.0SE Auto. It has been very useful, thanks.
I may have somthing to offer on the Alt. Fault probs.
I seem to have fixed this one by adding a fused wire from an ign. source, through a
5W 12V bulb then to the D+ terminal ( same one as goes to/from BECM, brown/yellow,
leave connected!) on the Alt. You could also use a relay, I haven't yet!.
This works as a charge light and seems to work fine. The power seemed not to be
enough from the BECM to fire the alt.
I strongly advise you all to try this BEFORE buying a new Alt.
Thanks again for the help, I'm sure I'll be back, my mum in the UK has a 97 4.6HSE with all sorts of probs!