Hi. I am hoping to pick the collective genius brain here about my issues. I have a few p0678 p0676 glow plug open codes being thrown. I tried to figure this out before coming here but I am a bit stumped. What I have done so far is:replaced the gpcm, replaced glow plugs and harness, and checked for continuity all the way from the GPCM to the glow plug harness, and there was continuity. When I ohm out all the plugs from the GPCM harness, only 1 of the glow plug circuits got a reading. I ohmed out the plugs from the glow plug harness and still only 1 reading shows up. I pulled the connectors off the plugs and checked for continuity and everything was good, so I am confused because there is continuity all the way from the GPCM to the glow plug harness. They are brand new plugs so I don't see how they could be bad. It seems like the new harness or plugs are bad if I cannot get an ohm reading from the glow plug harness or possibly they do not fit the glow plugs. So to summarize: there is continuity from gpcm to each cylinder glow plug connector but when I hook everything back up only one cylinder(on drivers side at least) will even produce an ohm reading. Any ideas? Thank you

 

When it comes to electrical, I'm not that Guy. We have others though that will chime in. Go through this video and see if you missed something and double check, report back.

You Tube

 

Also - please post where you purchased these parts.

 

honestly I don't remember I bought them a few years ago but I think it was Amazon or ebay. They could just be garbage off brand but they have continuity so I don't get why I can't get a reading through the harness to the glow plug and back to the battery.

 

Are you aware that there are two lengths of glow plugs for the 6.0L? Amazon/EBay has really caused problems for some folks with that.

What year model is your 6.0L?

 

It's an 07. I am aware of the different lengths and I matched the lengths before installing the new one. I'm going to ohm test direct on the glow plugs in about 45 minutes and see what I get and that should rule out if it's the harness or not, I think. I'm still stumped because I get continuity all the way up to the glow plug harness and all the way to each glow plug connection but when they are installed on the glow plugs I get no ohm reading from glow plug harness to negative battery, except for on one.

 

Sounds like the harness isn't making a good connection to the glow plugs.

-jokester

 

Thatsbwhat I thought too but I just tested directly on the glow plug and still get no ohm reading... so I tried to pull the plug and it just spins now... still can tighten up but endlessly spins when trying to remove it with a slight bit of tension. I don't know how I could've stripped it I didn't put that much pressure when installing them.

 

Well... pulled the plugs on cylinders throwing the codes... after struggling to get them out... all mushroomed heads. This is 1 day after installing new glow plugs so I'm not sure what to think... it seems like they must be complete garbage glow plugs and or harness. Hoping I can replace with better quality and it'll resolve this issue. Definitely not what I expected 1 day after putting in new plugs.

 

Oh and one more thing... checked my ebay purchases from over 4 years ago when I bought these plugs and what a mistake that was. Total Chinese garbage parts. Lesson learned. I'll report back after getting some new oem plugs installed.

 

I have an 07 and I'm in the market for OEM glow plugs and harness. Let me know where you get yours and the cost.
Thanks.

 

I think I'm going to get the set from prosourcediesel for 175

 

Prosource Diesel may be a good oem parts source. I do not know anything about them. I just called my local Ford dealer for a part and the guy knocked $60 off when I told him White Bear Lake's price(online Ford dealer). This made the price essentially the same when you take into account the shipping saved ( shipping sometimes takes a week). I have the peace of mind knowing I have a genuine Ford part. If you have a local dealer give them a call after you research prices at other reputable dealers. You might be surprised.

 

VERY well said @Brotherbillstruck .

I use ProSource Diesel for a few things, and I like them. Even so, I remain slightly cautious about them on a few things. ProSource Diesel is one of only a limited number of sources for engine/transmission harnesses. For that (even though the harnesses may be aftermarket) many 6.0L owners are extremely grateful.

There are several ways to get good pricing on parts from Ford or from dealerships. We post about it ALL THE TIME! It is crazy to buy cheap parts for "critical service" components.
AutoNation White Bear Lake
Tasca Ford Parts
Fairway ford Parts
FordParts.com
Bargain with your local dealership's parts counter folks.
CNCFab
RiffRaff
FullForceDiesel
KCTurbo
DieselOrings
DieselFiltersOnLine

In a few cases of the on-line businesses listed above, they may sell aftermarket parts, but the WILL stand behind what they sell and they care about the customers reliability (for example the RiffRaff silicone boots, or the engine harnesses already mentioned).

How many times have we seen problems made worse by people installing cheap parts (and many times these people INSISTED that they were OEM parts), but the parts came from Amazon, etc.. I know that some reputable (true OEM) parts are available on EBay, but a person had better be very sure of what they are buying!

 

At least we are getting somewhere.....