Hey guys, I recently had my 7.3L serviced for a variety of problems. It was running extremely rough and sputtering oil. My wife took it to a local shop that specializes in diesels, and they performed the following:
- Replaced HPOP and IPR
- Replaced o-rings on all injectors
- Replaced one faulty injector

At the time of service, they claimed to have checked all of the glowplugs, and that they all checked out ok. After we received the truck back, it ran much better, but we kept getting a pending trouble code associated with glow plug #6.

My wife took the truck back into the shop to have them look at it, and again they claimed to have hooked up a scanner and everything checked out ok. The owner of the shop said not to worry, as the code should eventually go away. It eventually turned into a check engine light, which we cleared, and has of course re-occurred again.


Flash forward to this morning, the truck is knocking under cold start. My wife let it idle for a while and the knock went away, which leads me to believe there actually IS an issue with glowplug # 6 or the associated circuits, despite the shop's opinion.

How do I go about troubleshooting this problem?

Is anybody local to Acton (near Santa Clarita) that could help me out? I really don't like the idea of taking it back to the shop to get raped again.

Thanks.

 

I apologize for not having the pin out, But what you can do is to check the the valve cover gasket plug, disconnect the plug and check where the resistance to each wire, I am going to keep looking for the ppin out, but here is the PDF for it.

Okay, I dont see the PDF, I will try again, here is the Pin out for the valve cover harness
GGIICIIGG...
G = Glow plug +
I = Injector +
C = Common Ground..

Look for a common reading between all the glow plugs

 

I think I got it,

I am now going to look for the resistance readings you should see.

Place on lead on a good ground (or battery ground) and then take the reading on each of the front 2 pins, then the back 2 pins on each side. These pins connect to your 8 glow plugs. A good glow plug will have a reading between 0.1 - 2 ohms.



Attached Images
https://www.ford-trucks.com/forums/1...l#post10168556

Okay, this should get you going, if you continue to have a problem with the glow plug, and your resistance is good, yo might want to pull the valve cover and check the plugs

 

Pat, you should try to look at that wiring diagram on a smart phone. I just opened it on my blackberry, you need a microscope to read it .haha

 

Thanks, hopefully I can figure this out when I get home from work.

Troubleshooting electronics is not my favorite thing to do...haha

 

Silly question, I assume that this should be done with the ignition cycled to on??

Is it required that the glowplugs be in the warm-up phase?

 

No Sir, power off for the Ohm Test..

 

I tried monkeying around with the truck but it got a bit late tonight for me to see outside in the dark.

I was having a heck of a time trying to pull off the 9-wire harness that leads into the valve cover. It appears as if there is a latch on the top of it that needs to be pried open, which I attempted, but the harness still would not give. Rather than break the latch, I decided to give it a rest for tonight and post here.

I searched here and other forums for a photograph of the harness and the latching mechanism, but could not find anything that illustrated how to get the harness to disengage.

Any advice or photos on this?

Secondly:

Before my truck went in for the HPOP/IPR and injector service, it never threw a glowplug related code, and as I mentioned earlier, the shop claimed to have tested the glowplugs when the valve covers were off of the motor.

What is the likelihood that when the shop re-installed the valve covers, that something went awry with the connection to/from the UVCH harness, and to the actual glow plugs themselves?

I am thinking that the reason they are trying to brush this whole issue under the rug and claim that there is no problem, is that they fear that they may not have put it back together correctly, and that there is a loose connection somewhere under the valve cover.

Furthermore, when my wife took the truck back to the shop for them to "scan" the motor, they claimed that there couldn't possibly be a problem, because they never touched any of the wiring associated with the glowplugs. To me, this seems to be patently false, because if they replaced the o-rings on all eight injectors, they would have to had to remove the valve covers and disconnected the UVCH harness from both sides.

 

You are correct that they would have had their hands in there, they dont ( I believe ) need to unplug the harness, but yes, they would have been in there.

Hopefully some one else can key in witht he picture you requested, I am not the talented to write and snap pictures like these guy here.

 

A glowplug won't throw a SES light on the dash unless you have a Excursion or Truck that was delivered to CA. They have a GPCM (Glow Plug Control Module) verses a GPR (Glow Plug Relay). The GPCM is configured to throw a code and trip the SES light. The relay style truck won't if its truly a GP issue. Look at this photo and you will see the relay (the one closest to the firewall). If you have two relays like the picture, then you have a non-GPCM truck and glowplug #6 (or any of your glowplugs) will not throw a code. A common problem that happens when installing the VC's is knocking off one of the injector harnesses that plugs into the top of the injector and you have a dead hole. That would throw a code and light up the SES light on the dash. The "don't worry about it" approach isn't acceptable. There's something up. You may need to take it to another shop.

On edit: yes they had to mess with the UCVH if they did injector work. That harness feeds the injectors and GP's.

 

I have an Excursion, which is a GPCM truck.

The code being thrown is a "P0676", which is a failure related to glow plug #6.

At this point, I can not afford to take it to another shop, due to the fact that we have dumped nearly $4,000 into it based on this job alone. I'm capable of fixing the problem myself, but as with most working professionals, I don't have much time to do so, and my wife relies on this truck to get around every day.

I am contemplating taking it to a Ford dealer to have them give us a written diagnostic to back up my opinion on what is wrong with the truck (disconnected wiring associated with the UVCH or glowplug) and presenting this to the shop.

If they claim that the problem can't possibly be related to the work they performed, or if they demand that we pay them to fix the problem, I will simply fix it myself.

This is why I have a hard time trusting mechanics. I normally do all the work (minor and major) associated with my cars, but I didn't have a lot of turbo diesel experience or the free time. I just really thing that it is reprehensible that a shop will not stand by the quality of their work and give you the middle finger when a problem associated with their work presents itself.

 

Here is some more info that might help you: http://www.thedieselstop.com/faq/949...les/032136.pdf

 

Where are you located? perhaps there's a fellow FTE'er close by. I would not recommend the dealer. This is a simple fix. Most likely the harness on the #6 GP wasn't pushed down all the way.

 

I'm located in Acton which is near Santa Clarita.

Some help from a fellow enthusiast would definitely go a long way. I've got all the tools.