I have a 99 dodge 4x4 diesel pickup. I went out to start my truck yesterday and the batteries were completely dead. After I popped the hood, I noticed that the air intake piece going into the grid heater was a brown or varnish color. I thought it was odd. I disconnected the batteries and charged them both back up. After connecting them again, I noticed that the little wire on the battery terminal was very warm. Then I put my hand on the air intake above the grid heater and it was warm. It seems like the grid heater is sticking on.

I then started my truck hoping that it would get the grid heater to shut off, but didn't have any luck. The alternator was only putting out about 8 volts. I then took the smallest wire off the battery terminal that was getting warm. That seemed to shut the gird heater off and the alternator when back to normal.

Has anyone had this happen? Does anyone know what the problem may be? What would cause the grid heater to stay on? Any help will be greatly appreciated.

 

You may have a relay that is stuck.

 

Can anyone tell me where the relay is or how to test it? Or possible cost for replacing it? thanks.

 

JUST WENT THRU THE SAME THING WITH MINE . FORTUNATLY MINE WAS COVERED UNDER WARRENTY, SO I DO NOT KNOW WHAT IT COST. THEY REPLACED BOTH THE GRID HEATER AND THE RELAY.
I HAD BEEN WIRING UP ELECTRIC BRAKES AND TRAILER THE DAY BEFORE AND THEY SAID IT HAD BEEN CAUSED BY THE RELAY STICKING BECAUSE I HAD LEFT THE KEY ON TOO LONG WHEN I WAS WORKING ON IT, BUT THEY DID ME A "FAVOR" AND REPLACED IT UNDER WARRENTY.
GUESS BEST NOT LEAVE KEY ON AND LISTEN TO THE RADIO WHILE I AM WAXING IT UNDER THE SHADE TREE WITH A BUD THIS SUMMER HEH?

 

I've left my key on for 3 hours before and never had a problem with the grid heater.

 

The relays are mounted on the driver fender well below the battery (there are 2 of them). Use a test light or volt meter, with the key off you should have voltage on only 1 side of the relay (test where the large wires connect). If you have voltage on both sides try unhooking the two small wires, if you still have voltage on both of the lager wires the relay is bad, if not the problem is elswhere.

 

Thanks for the help. I'll try testing the relays... I hope the grid heater is still good.