atc250r

My intake heaters are not working. There is power into the relays but not out. I found this schematic while looking for info on trouble shooting:



I have tested the side of the circuits between the relays and the ECU and it seems to be working normally. When the key is turned on, the ECU grounds the YL/BK and the OR/BK wires in an attempt to turn the relay on. Since the diagram I have is incomplete I am guessing that the BK/TN (in my truck its actually different colors but that isn't important I don't think) should be connected to a constant battery positive through a fuse of some sort. I'm not getting that from them. In fact, I'm getting a ground out of them. What fuse sends the power to those two wires? Can someone tell me if there is another relay that sends power to those terminals? If so where is it? I want to rule out everything else before condemning the relay's themselves. I could probably remove those two wires from the relay's and make my own harness sending power to them directly from the battery but that won't tell me why there isn't power coming into the relays from the stock wires.

Thanks.

John

infidel

Here's a better schematic
http://dodgeram.org/tech/dsl/trouble...niford_htr.htm

atc250r

Thanks Bill. That confirmed my suspicion, there should be +12V at the LG/BK wires in this diagram:



I went outside and checked fuse #9 in the dash fuse panel and its OK. I've got to figure out why there is no power at the relay now.

John

infidel

If I'm not mistaken the fuse that supplies the positive trigger signal at the relay powers several other things including the hold up coil of the shutdown solenoid.

atc250r

Hmmm. I need to figure out where/what "F18" is. It seems from that diagram that it does indeed power the fuel shut down solenoid so since that is working fine, there must be a bad connection that is not providing the voltage to the grid relays and from the looks of it F18 has something to do with it.

John

atc250r

If anyone could tell me what and where F18 is I'd really appreciate it. F18 is on the right hand side of the second diagram I posted. I'd bet its in a factory service manual somewhere but I don't have one. Meanwhile I'm going to spend my day off freezing my butt off outside trying to fix the truck.

Thanks.

John

atc250r

It's amazing how much better you can diagnose something when its not half dark and 15*F with 30-40mph winds blowing. There was power at the green/black wires, as I would pull that wire on and off I could heer/feel the relay clicking albeit a very weak click. There is power going into the relays but not coming out so I'll have to decide if I want to go with the two Ford starter relay's to make my own or just go with the relay kit from rockauto.com. I can't find the part on NAPA's site or I 'd consider just buying it locally. Oh well.

John

atc250r

I ordered a set from www.rockauto.com since no one else listed them. Just an FYI, a Mercury Marine starter solenoid is a good replacement and doesn't need to be insulated from ground like some of the other starter relays that can be used to turn the grids on and off. I just happened to have one here that will go on the boat in the spring and I figured I'd see if it was isolated or not and it turns out it is. The Mercruiser part number is 89-68258 and it was about $28 from www.mercruiserparts.com. I'm guessing that it is probably a heavier duty piece than the stock relays but I didn't want to fool around with mounting it and stuff since the price was the same and the stock style lasted me 12 years. I found some cheaper marine replacements on ebay for $15 each but by the time you figure in the shipping charges you don't really save much and have to go through some extra work.

John

grover

look at the parts store for snow plow solenoids they will work

atc250r

That's a great idea. Hopefully I won't need another set for another 12 years.