What controls or regulates the grid heater from cycling??? Mine seems to stay on therefore making the alternator work overtime and no charge to battery. I disconnect it and I'm fine. Got my 14 volts back. Hook it up and I'm at 10 9 12 all over the place.

 

The PCM controls the grid heater cycling. There are 2 relays on the driver's side fender kind of underneath the battery tray for the heaters. They do go bad from time to time, I would check them to see if maybe they're sticking.