In the past (when the truck started fine) I would turn the key to the 'wait to start position' and the voltage would drop just a hair in the dashboard which I'm assuming was the GPR kicking in and giving voltage to the glow plugs, I JUST put a brand new relay in, that drop in the dashboard voltage doesn't happen and my truck wont start...

Is there anything else I should be looking at? The glow plugs themselves are new as well and when I'm turning over the engine, smoke is coming out of the stack. Is there a fuse I should check? I checked fuse #22 and it's good...

I jumped the glow plug relay lugs for 30 seconds and the beast started right up...she wont start cold though...brand new GPR in it too...

 

Either the GPR is the wrong part, or it isn't working because of some other reason. Use a meter or electrical test light and verify it. With the key off, you should have power on 1 of the big terminals. With the key on, you should get power on both big terminals and one of the small ones. The other small terminal should be connected to a ground, so if you clipped one lead to one of the big terminals and touched that one (small, ground) lead with the other terminal, you should show power there as well.

Make sense?

Ie, key on, three of the four terminals (2 big, 1 little) should have power, and the other is a ground for the relay (controlled by the PCM). If that's not what you're getting then you have a bum relay (or the wrong one...) or a wiring problem.

 

Both small terminals with key in the on position register 1.38 volts and only ONE of the lugs registers 12volts, the other lug registers a negative 16.....however I did test while the engine was already warmed up (if that makes a difference...)

 

Yeah, something there isn't right. There should be one wire there (pink/orange) that is a ground when the PCM is calling for the Glow Plugs to run, but the other small wire should be a 12V+ with the key in the run position.

Maybe unhook the small wires and test things? If you don't get power on both large terminals the GPR is not turning on the glow plugs.

You do get a "Wait to Start" light when you turn the key on, correct?

 

I do get a wait to start light when I put the key in the on position, yes

Gonna have to figure this thing out somehow... I wish I could just buy a damn RELIABLE GPR and be done with it...I keep hearing about this 'western plow' relay but I can't find anywhere to buy it online...so I'm stuck buying these tiny cheapo aftermarket POS relays...I'm on my 3rd one right now and it's starting to look like this one is screwed too...

I will test tomorrow when it's daylight out and make sure the wires are pushing the correct voltages out...always the GPR with my truck I swear...although when I jump the lugs for 20 seconds or so, the beast fires right up! Don't know if that will hurt the truck or not but it's a workaround for now!

 

Jumping the lugs with a screwdriver or whatever, is just a way of manually activating the Glow plugs. It won't hurt a darned thing. That's all the GPR does, it just does it automatically.

NAPA sells a good GPR for these trucks. Ask for a GPR109 (I think that's the number). I had one of those in my old truck and it worked just fine. In this truck I did the big daddy "Stancor" relay for a GPR. It's probably overkill, but I should never have to worry about it again. I have heard guys swear by those Western Plow relays as well, but those are a couple different options you might check into as well.

 

Stancor relay was the one I tried finding as well but was unable to unfortunately.... Would you happen to know where I could get one for a 1996 F250 7.3L Powerstroke?

 

I bought mine from Allied Electronics online. Here is a link.
And Here is a link to Guzzle's How-To on installing the Stancor. You probably already know this, but it doesn't fit real well in place of the old relay so if you're still using the engine cover, you may have to get creative...

 

Thanks for the links! I'll check this out definitely

 

Seriously? Um, the Stancor and WP relays are NOT made for specific vehicles. They're generic. And VERY widely available.

WP:
Western snow plow solenoid motor relay 56131K-2
SAM Motor Relay for Western Plows — Replaces OEM Part# 56131K, Model# 1306301 | Solenoid| Northern Tool + Equipment (shoot, if this is stocked at the retail store [no shipping], it's a steal)
Western Solenoid Motor Relay NS 56131

Stancor:
Monster White-Rodgers Glow Plug Relay
586 105111 White-Rodgers | Mouser
586-902 - WHITE RODGERS - CONTACTOR, SPST-NO, 12VDC, 200A, BRACKET | Newark element14 US

This took aprx. 3 minutes.

 

News to me. I didn't know they were generic and all I ever searched for was 56131K-2 to which I couldn't find anything...

I ordered a new one from gotglowparts.com -- hopefully this will solve the relay problem once & for all.