Hi, I've been lurking for a while but this is my first post.

I live in western WI and I have an 02 EX with a 7.3 that's been starting a little hard lately. We've had a few cool nights of 0-10 degrees and it was very hard to start. This thing has always been reliable to -10 without pluging it in so I knew something was up.

I searched the forum to understand how the glow plug relay worked, checked to see if it was energizing when the key was first turned on. It wasn't so off to NAPA to pick up a GPR 109 or 110. Ended up with a 109. Stuck it in and I have the same issue, it doesn't energize. I get battery voltage up on one of the small terminals when ignition is applied, but I'm assuming the ground is switched from somewhere and isn't happening. I tested the old one on the bench(like I should have done prior to the trip to NAPA) and it energizes fine.

I have now found a post that indicates that Excursions also have a device called a glow plug control module (GPM). Does anyone have any experience with these? Do they fail often and is there a way to test them?

When I called NAPA and told them I wanted a GPR they tried to order me a AR6036, although it was listed as a glow plug relay I'm suspisious it might be the module. It also had a price of $176.00 as compared to $22.00 for the 109 relay.

Any quick help would be appriciated.

Thanks

 

I posted that earlier today from memory. I finally found it in the service manual just now.

"Glow Plug Monitor
A diesel engine calibrated for California vehicles under 14,000 GVW and all Excursion vehicles utilize a Glow Plug Monitor (GPM) system designed to locate failed glow plugs or failed wiring in the glow plug system. Diagnostic Trouble Codes (DTCs) indicate which bank has failed glow plugs or failed glow plug wiring.

The California glow plug system is composed of solid state Glow Plug Control Module (GPCM), glow plugs and the associated wiring harness. The glow plug on-time is controlled by the Powertrain Control Module (PCM) and is a function of oil temperature, barometric pressure and battery voltage. The PCM enables the GPCM which drives the individual glow plugs. Glow plug on-time normal varies between 1 to 120 seconds. In addition to the PCM control, the GPCM internal limits the glow plug operation to 180 seconds regardless of PCM commanded on-time. The power to the glow plugs is provided through the GPCM solid state drivers directly from the vehicle battery. The GPCM monitors and detects individual glow plug functionality, and the control and communication links to the PCM. The failures detected by the GPCM are passed to the PCM using a serial communication signal on the diagnostic line."

I was just reading over the test procedure for the GPCM, and it looks like you'll need a breakout box and a scan tool set up as a frequency meter to test it.

 

Thanks, I took a chance and replaced the GPCM to see if it would have any effect. It's 10 degrees this morning, the truck was left out all night. I checked to see if the relay fired this morning and it didn't. Where to next? I have a new relay and also a new GPCM module.

A google search turned up a tsb04-22-8 it says:

7.3 trucks with elcctronic gpcm may exibit hard start or no start when cold. It may be in the harness. use repair kit 4c3z-12b568AA.

????

 

hi having same problem with my truck starting verry hard in the mor. checked the gpr and power in but no power out when key is on. i also have good voltage at one small terminal when key is on. let me know how you made out

thanks gabe

 

What type of truck Gabe? I'm chasing this on an Expedition which uses a module that's not on others except in CA.

 

hey dog

truck is a 2002 f350 psd so i guess it dosent fall into the same catigory. thanks anyway.

gabe