My 140 amp alternator fuse blew the other day and I tried just replacing it but after about 1 day it blew again. After checking things over I tried removing the leads to the relays for the engine heaters and all is well. Does this mean that the heaters are shot? All the wiring around the relays looks fine. Also what's a good source for replacements and how much do they run?

Keith

 

Have you checked the heater relays to make sure they are not sticking? This could cause the grid heater to stay on and possibly blow the fuse.

 

No I haven't. Not sure why but right before this happened my dad said he saw some sparks coming out of the wheel well near the relays but I can't seem to see anything wrong with them or their connections. But I haven't inspected them too closely.

Keith

 

I had almost the same problem with mine and it was the relays. I replaced them and everything is normal now.

 

I've noticed on mine even after a hot shut down and restart (2mins between start and stop) my grids still cycle, I have not dived into it yet but I'm thinking I must have a bad sensor (ECTor IAT or something) I'll post my results once I test everything.
I agree with the above posts, sounds like stuck on relays, very easy to test for with a test light/ or hook up a light to the grids and run it in the cab and see how long it stays lite.

 

wheres the best place to get the relays? I had trouble with mine sticking a couple times last week. Both times I shut the truck off, restarted it and everything was fine again.

 

My heaters stayed on so long that they burnt the bottom of the intake horn and it was nothing but the relays.
afoulk, I got mine at RockAuto.com. They were the cheapest I could find. 57.95 identical to the stock relays

 

For as long as I can remember mine have cycled if it was below 60 degrees regardless of weather or not the engine was at full temperature.

Maybe I am half asleep still but I went to Rock Auto and didn't see what section the relays were under.

Keith

 

PM Infidel. He should have the P/N handy for some Ford relays that will do the job for much cheaper.

 

I would just remove the leads all together and get the Grid Delete! My truck starts fine at 20* without the heater and you get much better air flow.

 

Keith they ae not easy to find. I will look tonight and send a reply with directions.

Bill

 

At Rock Auto web site select your truck, then select Electrical Sw. and Relay and then select Accessory power Relay.
This is the part # listed.

ACDelco Part # C1711C (#19136396)