Gtra Altenator Wiring / Output

I have some altenator (Motorcraft 85 amp alt) probs and would appreciate some input from fellow GTRA owners or others with Motorcraft altenator and PI dash fitted to their cars.

The PI dash was telling me that the altenator was producing over 16 volts when the engine was around or above 1500rpm (was over 14.7 volts at anything over fast idle). We cooked an MSD Blaster 2 coil while out testing (case expanded up and oil coming out) so I decided it was time to rectify the apparent overcharging issue.

Removed the altenator and had it tested, man who tested it told me the regulator pack was blown so yes producing over normal voltage. Shipped altenator off for rebuild and refitted it. You guessed it, same over volt readings as before.

Questions;

1. What voltage reading do you get in your GTRA's on PI dash when engine is at a steady 1500 rpm?

2. What is your altenator battery feed wire attached to (photo would be appreciated)?

Any other experiences with this prob and solutions appreciated (and yes I am a mechanical engineer...............not an electrical one.......!!)

No clue... car isn't with me at the moment. Look through my thread and see if any of those shots show you the wiring setup.

No clue... car isn't with me at the moment. Look through my thread and see if any of those shots show you the wiring setup.

Cheers Brian, had already looked for this shot previously but no joy.

I suspect that I may have 'manufactured' this problem when I have rewired the car when converting from injection. Possibly related to dropping out the system voltage signal back to the regulator ('A' input to regulator). When I have traced and fixed I will let you know what the problem was just in case it happens during your conversion as well.

1. What voltage reading do you get in your GTRA's on PI dash when engine is at a steady 1500 rpm? Mine is reading up over 16 volts

2. What is your altenator battery feed wire attached to (photo would be appreciated)?

Voltage reading on dash should be around 14.1 - 14.3 volts and voltage at battery around 13 - 13.5 if alt is charging OK.

I found what seems to be the problem with my car, the loom wire attached to 'A terminal' input on the voltage regulator (on the back of the altenator) was run as a 'hot on run / start' wire the same as 'I terminal' wire (good wiring guide for the altenator is Ford 3G Altenator Installation diagram that I found by Googling on the net).

I simply re-routed the A terminal wire to the B+ terminal on the back of the altenator and hey presto, over charging problem solved. Now showing 14 - 14.3 on PI dash as it should.

This is not a wire that I have previously touched so there may be other cars out there with the same issue.

Nice detective work!