LUVTruck.com

Every once in a while my charge light comes on. Of course, once that happens the fuel pump quits.....

1 The VR may not be supplying field voltage.

2 The alternator may not charge if it has field voltage.

3 Even if it is charging, the W terminal may not be getting voltage through the white with green stripe wire.

4 Even if the core relay has voltage, it may not close sending power to the light and fuel pump relay.

Any good ideas how to find out which one when it works fine at home in the garage?

I think I am going to wire an LED to the w terminal and see if it has power when the light comes on. I have one set up from previous troubles.

W terminal on mine had a white/red wire. As you probably know the ignition switch sends power to the regulator through the "I" terminal, then out the "F" terminal to the alternator field. After charging begins the regulator then sends power out through the "W" terminal to the fuel pump relay. As you can see there are several terminals to monitor to see where you loose power. Be sure to check the fuse box connections as this is a known problem area.

The thing failed yesterday when I was messing with it. I don't seem to be getting good voltage out the field terminal. I ordered a new voltage regulator today.