Hello everyone,

I have a 2002 F-250 7.3L that I have been slowly fixing all the trouble codes listed on my scanner. I've finally cleared all the trouble codes but now have a GPR that will not activate. I have turn the key on and have power at Both small terminals and full time power on the bigger terminal but the relay will not click. I installed a new relay and got the same results. Now with the removed "old relay" if I apply 12v to the large terminal and one small terminal and then apply ground to the other small terminal the relay will activate. Like I said earlier..."Both the small terminals have 12v when the key is turned on. Is their a problem with my PCM ?

Thanks for any and all help.

Joe Garcia

 

You need to be sure its a GPR ,,not a starter relay ...

Power on both small terminals means the PCM has sent the ground signal...

Are you sure you are working on the GPR & not the IAH relay?...

 

I hear what your saying. But the one I tested was the original one off the truck and it wouldn't click unless the second small terminal was applied with a ground signal.

Joe

 

The GPR is the rear-most one. The front one is the AIH relay. You should see battery voltage on both LARGE terminals if the relay is activating correctly when the motor is cold. Have a helper turn the key to the ON position while you check both large terminals. If you're not getting it on both, it's probably bad. Check out the Stancor on guzzle's page:
Welcome to guzzle's Stancor GPR replacement Mod Web Page

 

Hi,

Yes I'm working on the rear most relay and their is no power to the large terminal going out to the glow plugs when the key is turned on. I have power on the large post and power at the two small post. The new relay will not activate unless one of the small terminals is applied ground. That goes with the factory one removed which I thought was bad and the new one I just installed.

 

Okay -- I admit I breezed through your post and missed the part where you replaced it already. Sorry about that....

If you're grounding the control terminal and it's activating, the relay is fine. It could be that the PCM is doing something wrong, but I'd bet on a wiring problem before the PCM. I'd be very surprised that the PCM would fail in ONLY that way.

 

Not a problem....any suggestions as to where to look next are appreciated I'm thinking the PCM but will look at any leads at this point...LOL

 

You're going to have to start tracing the wires back to the PCM. Like Joe had stated the probablilty of the PCM just going out on the GP control is highly unlikely. You probably have a broken wire. Is your truck a California model? The GP circuit is a bit different on those.

 

Man, I don't have any pointers for you. I'd have to bust out a service manual to see where the wiring goes.

All I can add is that the reason you're seeing 12V on both control terminals is because it's a straight through coil that's grounded to activate. Without a ground on the far side of the coil from the battery source, it stays open and 12V is there. Once the PCM grounds the control line, the coil is "energized" and the relay closes. It's very simple -- why yours isn't working is not so simple. I wish you luck!!

 

Hey that's alright..nothing is ever easy! I will break out the wiring schematic page and my glass and see where those two small wires go and start tracing.

Thanks Again Everyone

 

I forgot to mention the truck is a California Model...

 

But you have 2 relays on the top of the engine right???

 

THen you have a GP controler instead of a GPR

Is this what it looks like ?...

 

Yes I have 2 relays on top of the motor.

 

If you have two relays that look the same ,I don't think it is a cali model...