I am trying to rule out the GPR for my starting issue and have noticed that my 2002 7.3L has two GPRs (one is shorter and behind the other). Am I seeing things? Are they both GPRs or what? Which one should I be testing and or replacing to rule out hard starting? Thanks!

 

The relay in front is for the AIH.

Do test the GPR for power to the GP's at cold start. Next would be to ohm out the GP's at the VC harness and verify they are all good. The outer (4) pins are GP's...

 

One is the AIH(Air Intake Heater) Relay...The one to the front. The rear(towards the firewall) is the GPR(Glow Plug Relay).

 

The one closest to the firewall is the GPR. The taller one in front of it is the AIH (Air Intake Heater) Relay.

EDIT: You are both to fast for me.

 

No you dont have 2 GPR's the one in the front is the relay for the AIH the one behind it is your GPR.

 

Blowing smoke off pistol...

 

You're a regular Quick Draw McGraw.

 

Thanks for being so fast with the replies!

 

I think he meant Quick Draw SkySki lol.
Turn your key to run which will turn on your GPR. The LARGE lead on the passenger side should always be 12 volts(hot). The large lead on the driver's side you want to have 12 volts on it after you turn the key on.
Turn your meter to DC voltage. Place Red lead on the Large Drivers side terminal and the black lead on a good ground or the battery negative post.
Do you have 12 volts present?
This will just show you if you have voltage present and it can not tell you if you have current flow to each glow plug.
I hope I have not taken you to grade school on the use of the meter. I just want you to know exactly how to check your relay when you turn your key to on/run.
Dwayne

 

Thanks Dwayne! Got the basics on voltage but do you have the proper technique for measuring the resistance? I know it should be low (1.5 or so and not 800). What posts do I check for that?

 

It's best to remove the plugs to the under valve cover harness and read each glow plug from the four outer terminals of the socket. Depending on how accurate your meter is, a few ohms is good.

 

Unplug harness from VC gasket and put one lead to ground and the other lead to the GP pins. Its a little awkward, but is a lot less work than pulling VC's. Personally - I'd prolly just replace GP's if I had the VC's off and I would never just replace 1 or 2 GP's. That said, my Excursion has 270k miles on it and GP's still ohm out just fine.

I'll see if I can find a pic or pin-out diagram, but its pretty easy - the center pin on VC harness is 'common' for the injectors, the next 2 in each direction are for injectors and the outer 4 pins are for GP's and are relative to their location. Clear as mud?

Like this G G I I C I I G G...

 

Here's everything ya need to know and more!

https://www.ford-trucks.com/forums/7...pr-system.html