This afternoon I started my truck and noticed the "check engine) light on. Got home scanned with my AE and found the code "P0674 - #4 glow plug circuit fault".
Now what?
I have not noticed any issues when starting. But I would want this issue taken care of because winter is fast approaching and I do winter camping with my young boy.
I have never changed a glow plug and am not sue I am able to. Is there something I can check before a glow plug must be changed?

I need to drive my truck daily. Just until I have this fixed. Am I causing other issues if I do?

 

Wow, we've got an epidemic. Mine is #3. Another post today was for #5.

It won't hurt a thing to drive it with an inop glow plug. They turn off after a couple of minutes after starting anyway. Obviously it may affect starting as temps dip.

Mine is going in the shop tonight.

 

What were you quoted for replacement?

 

Haven't asked yet. I'll get an estimate when I take it in tonight. I believe your #4 is easier to get to than my #3, but I don't know if that makes any difference on flat rate. Probably not.

Are you over the 100k warranty?

 

yes. by about 4K and 3 months.

 

Well of course!

 

HUH!!!! John, you got a CHECK ENGINE light in your truck?!!!! Well God forbid!!!!

All joking aside John, disconnect the four wire connector that is clipped to your FICM mounting bracket (the one with the red lock tab). Using an ohm meter set to OHMs (preferably one that auto ranges), connect the red lead to each of the four female cavities with the black lead connected to your driver side battery ground terminal. Each of the four terminals should give you no more than 2 ohms readings. If this test checks out good, your GPCM likely needs to be replaced, provided the circuit is good between the engine harness side that connects to the GPCM and the glow plug harness. Yes, and P06XX glow plug control system codes WILL throw the CHECK ENGINE light on, because it is considered an emissions affecting component.

Anything else I can help you with, John?

 

First time for everything. It's been 5 years without a cel light of any kind. Back under the hood I go.
Thanks Mike your advice is alway welcome and on the money every time.
The sucking on a tube attached to each hub workedm along with testing the PVH solenoid. I need a new PVH solenoid.

 

Readings are:
Blue = .001 ohm
White = .001 ohm
Red = .083 ohm
Yellow = .001 ohm
So it looks like my GPCM (glow plug control module) I assume, is toast. How hard is it to replace and where is it located?
Thanks Mike.

 

Check to see if the red wire runs to the afflicted glowplug. If so I might still suspect the glowplug because it's 83 times higher than the other 3 and the scale might be off on the DVOM. Totally guessing here, BTW. Also, was the connecter full of oil, by chance?

 

The GPCM is on the front corner of the passenger side valve cover. About 5 minutes to change it. I changed mine about a year ago, and I think I paid about $125 for the module. For that time and money, if I had any doubts, I would change the GPCM first.

Looks like this:

 

Well John, I guess it's time for you to get your hands dirty on your truck. Those readings indicate that you have an issue with your cylinder #4 glow plug and/or glow plug wiring. Even using the proper glow plug harness removal tool though, you would still likely end up ruining it during the process of removing it so I would pick up a new harness and a cylinder #4 glow plug. Actually, you might as well replace cylinders #2, #6 and #8 while you have the harness out anyways, for what the glow plugs cost.

And before you ask, the part numbers for the glow plug harness and glow plug are ZD-13 (glow plug) and 5C3Z-12A690-A (glow plug harness, left side).

HAVE FUN!!!

 

Thanks Mike. I was hoping it would be a simple module change.
Any tips, advise or instructions on this procedure?
How long of a job would this be?

 

Isn't that what we always hope for?
Well, if you remove your air cleaner housing, the glow plug harness should be fairly accessible. Like I mentioned in the above reply, you are more than likely going to ruin the glow plug harness during the removal process so it would be a very good idea to have one on hand before you dig in. I would start by SOAKING all four of the connections liberally with PB blaster or penetrating fluid where they enter the rocker arm carrier into the glow plugs. Finesse will be your friend as you pull apart each of the four connectors out. Then get your 10mm deep socket to remove the glow plug(s). Torque the new one(S) to 14 ft-lbs. Dap some Vaseline around the o-rings of the new harness before you push them into the rocker arm carrier and onto the glow plugs.

So what else are we going to fix on your truck today John?

Did you get your PVH solenoid issue resolved yet?

 

I was planning on dropping by next week to have lunch with you and pick up a PVH solenoid at your dealership...now this. Might have to hold off the solenoid until this one is resolved. I was planning on spending some money on the wife's birthday gift, next month. Oh well she'll understand (the wife).