When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
I have a 2002 F350 301,000 miles on it that has been having trouble starting in the cold but if I cross the big lugs on the glow plug relay it fires up just fine. So I ordered a new relay and put it on today and after I put it on I went ahead and was servicing the truck. While servicing the truck I smelled something hot and it was the new relay. So I immediately unhooked the battery, then removed all the wires from the relay and I tested each wire and everything seemed right the large red wire had 13 volt, the small red wire had 13 volt and when I turned the ignition on the small orange wire grounded for almost 2 minutes then it cut out. So I rehooked them all up and turned the key on and the relay wasn't energizing across like it should. Then out of no where my AC clutch starts clicking like it was trying to engage and now inside the cab there is an intermittent clicking and the truck wont start now. I messed with it all afternoon and its almost like I fried something in the truck but I cannot find any wires that look burnt or shorted out and I wasn't having any of these problems before I tried to replace the relay. Ive had several 7.3 trucks and have replaced relays in the past with no problems. Any idea's?? Thanks
It sounds to me like the new relay was latched and drew your batteries down in a hurry. Low batteries will result is relays clicking/chattering. Charge them puppies up and go from there
What other "servicing" were you doing to the truck? You sure the two are absolutely related? Drained battery is a good guess, but I always get skeptical when people make multiple changes to their truck at once. I stopped doing multiple jobs at once long ago. Had too many times where I thought, "Well I just did 10 new things on my engine today and now it won't start, where do I even begin?"
Well I replaced the Oil Cooler, then a new water pump, thermostat and thermostat housing. But really the only electrical work I did was on the GPR. But I kept searching last night and located the chattering relay in the cab and it was the Injector Driver Module relay. So I did a search on it and turns out if the F22 fuse is blow which looks like for the PCM it causes that relay to click rapidly. So I replaced that fuse and everything is working again except I still cannot get my new GPR to work. I checked all the wires and everything checks out good. On one big post I have my 12v feed wire, then other big post I have the wire that goes to the glow plugs, then I have my small red wire that feeds 12v when I turn on the ignition, then my small orange wire grounds for about a minute and a half when I turn on the key. So I hook them all up and it doesnt feed 12v across when I turn the key on to the other big post. So after doing some testing I left all wires hooked up except I unhooked the small orange ground wire. After removing it with the key off the small lug it hooks to is grounded already with no wire attached to it... that cant be right can it? Also noticed that when I have all the wires unhooked and the relay in my hand I can put 12v to one small lug and touch the case of relay to ground and the relay clicks so the case is grounding allowing the relay to close. Are these relays supposed to do that like they are case grounded? I tried also leaving the big wires where they are and reversing the small 2 wires and when I turn the key on it drops the entire truck voltage down to like 8 volts you can tell its putting a hard strain on the batteries. Both batteries are newer and both test good and I have had no problems with low voltage or battery issues leading up to working on the truck this week. I am starting to think they sent me the wrong relay or maybe a bad one? Thanks for the replies and info I really appreciate it.
Here’s a picture of how everything hooks up with power and grounds. When the GPR activates you’re gonna see voltage drop to 10.9-11.3 ish with good batteries and all 8 GP’s working. Just because a battery is “newer” doesn’t mean it’s good. I would have them both load tested then you’ll KNOW if they’re good and won’t drive yourself crazy chasing your tail.
Ok thanks for the picture, I charged the batteries up and then let them sit for a day then when I got up the next morning I load tested them and they are both showing good so I think I can cross that off the list. What I am trying to figure out now is why PCM ground post is grounded with no wire even hooked to it? I can't imagine how or why it would be grounded already with no ground wire hooked to it. Thanks
I apologize if you already checked this, but are you sure it is an actual glow plug relay?
Check to see if one of the small posts on the relay has continuity to the relay base where it bolts to the bracket. This would explain the ground condition you are seeing. Just a thought.
EDIT: Just re-read your earlier post, I don't think the relay should ground through the base. Either its the wrong relay or something has failed on it causing your grounding problem. 8 volts with the relay closed and the glow plugs active also sounds like low or bad batteries.
Ok thanks for the picture, I charged the batteries up and then let them sit for a day then when I got up the next morning I load tested them and they are both showing good so I think I can cross that off the list. What I am trying to figure out now is why PCM ground post is grounded with no wire even hooked to it? I can't imagine how or why it would be grounded already with no ground wire hooked to it. Thanks
You actually LOAD tested them (individually) not just charged them and checked voltage? You never answered me earlier, is it an actual GPR not just a relay?
Those are easy to screw up, I ordered an Alliant GPR and it had the exact same stamps and marks on it as a regular relay. It came from a reputable source but was dead in a month.
It's best to just get the "Stancor" relay and never look back.
After removing it with the key off the small lug it hooks to is grounded already with no wire attached to it... that cant be right can it? Also noticed that when I have all the wires unhooked and the relay in my hand I can put 12v to one small lug and touch the case of relay to ground and the relay clicks so the case is grounding allowing the relay to close. Are these relays supposed to do that like they are case grounded? .
No they are not and there is your problem. The mounting bracket is supposed to be isolated from the relay, just to be sure I went out to the shop and grabbed a working GPR and connected 12V to one of the small terminals and touched the bracket to ground, no latch. Put 12 V to the other small terminal and tried again. No latch. Then I touched the other small terminal to ground and it latched. Reversed the + and - and touched the small terminal to ground again and it latched. In no case did it ever latch by grounding the mounting plate, and a DOM shows zero continuity between any terminal and the mounting plate.
You either got a defective relay or the wrong one and that is the cause of all your issues.
Ended up being I got a defective GPR it was case grounded causing all my problems. I went to NAPA and got another one and it fixed it, fast forward to today and the new relay stuck on again draining my batteries. So I did some research and I think my batteries are weak causing low voltage/high amperage and that is what is causing my GPR's to stick and burn up. So went and bought 2 new batteries and another GPR. Replaced the batteries and for some stupid reason I hooked them up before I changed the new GPR and when I was pulling off the small orange wire I accidentally touched it to the Big red power feed wire and got a small arc. Never thought much about it i finished installing the new relay and now the truck will not start, it cranks but no smoke from the exhaust it isn't even trying to fire. Any idea's what I could have fried? I tested all the fuses under the dash and can't find any that are blown. I dunno if it makes a difference or not but my Tach also is not moving when I crank the truck over. It's a 2002 F350. Thanks!
Did you test fuses under the hood? I’m not sure about the 2002 but typically the tach won’t move if the CPS is bad. I would test all the fuses with a test light. Slow down and focus on what you’re doing.
Rezvani's Latest Post-Apocalyptic Monster Is a Ford F-150 Raptor Underneath
Slideshow: Called the Fortress, the 850-horsepower pickup combines Raptor underpinnings with military-inspired features, survival equipment, and a starting price of $285,000.
