Late build 2004.

Truck threw a P0676 code. Did some research on the forum/internet & found that it is the #6 glow plug. Found a few threads that said it was typically a GPCM problem. The individual glow plugs and the OTC harness tool were cheap enough. Thought I'd start with the GPCM & then move to the glow plug itself if needed. Purchased a GPCM, a glow plug & the OTC harness tool. Figured I'd buy a harness if I got that far.

Started the job a few days ago but the rain chased me off. Amazingly, wiggling the connector (black) seemed to fix the problem. Drove it on a few errands & then to work where it sat for 48 hours (firefighter) before driving home. Probably 6-10 'starts' with no CEL. Well, yesterday afternoon it came back. Wiggled the connector but no joy.

Today, I replaced the GPCM but that didn't cure it. I then removed/replaced the #6 glow plug. Unfortunately, that didn't fix it either. I was surprised to find the harness plug wet with oil (?). At least I'm pretty sure it was oil. Honestly, it could have been diesel. Cause for concern??? Also I thought I lucked out but unfortunately, I broke the connector. Honestly, it is much easier for me to replace hard parts than figure out wiring issues. I don't have much skill or patience for electronic gremlins.

So....I know I should replace the glow plug harness. Before I do that, I need to either figure out how and if I'm going to finish the repair myself. If I take it to a shop, I'm guessing that'll want to rule out the glow plug. I'd hate to have to buy two glow plug harnesses.

Any ideas on what I should be testing electronically?

Honestly, I don't immediately need to fix this issue. I really will only need to do it so that I can smog the truck (California). Seeing the CEL does bug the heck out of me though. BTW, the only issue the truck seems to have is an wierd slightly rough idle every now & then. No rhyme or reason when it does it.

Thanks

 

I have a similar issue on number 5. They all ohmed out good so going to check this from a post I found.

https://www.ford-trucks.com/forums/1...ode-p0670.html

 

This is what I used for testing. Should almost be put in the tech folder. Couldn't find anything in there for glow plugs.

https://www.ford-trucks.com/forums/1...low-plugs.html

 

Sounds like one of your little O-rings failed on the glow plug harness and it's leaking oil. You can check each plug at the 4 pin connector (Rusty's post) or at the plug itself.

Sounds like your going to need a harness and maybe 1 glow plug.

Be careful not to over torque the plugs.

.

 

Thanks guys.

CPB1, I definitely need the harness as I broke the connector for #6. The #6 glow plug is a brand new oem unit.

Woodlander, went out to double check that I had the plug in correctly/all the way. I know that it definitely 'clicked' in when I installed the new GPCM but it was tight. I tried to remove the connector to lube the gasket with some syl glyde but couldn't. In order to get it all the way off, I'd have to loosen the CAC tube & remove the GPCM to remove the connectors. I'm not going to do that in the dark & rain tonight. I was able to unlock the connector & move it back a bit before it ran into the ICP sensor. I'm pretty sure I've got it connected correctly. I need to go out in a bit. If it is as simple as that, a new driver's side glow plug harness & I'm all set.

 

Well.....the truck didn't have a CEL for the last two start ups. I'm going to order up the driver's side glowplug harness so I can replace it. As I said, I broke the connector for glow plug #6. Makes me wonder if it is just a connector issue.

If the CEL comes back again, I've gotta believe it has something to do with the connector at the GPCM. I did check for earlier but didn't see any evidence of wire chafing. I'm debating whether or not to pull the connector to lube the gasket.

Anybody know if they sell a replacement connector/pigtail?

 

Here is something I posted a while back on some info
that I got from the Service Manual
https://www.ford-trucks.com/forums/1...ce-manual.html

Also watch this video by DieselTechRon at about 2:30 in
He shows how to use the harness tool so that you don't break things.

Sean

 

Thanks Sean. Read that thread today & watched that video. Pretty sure I had the tool seated completely but I could be wrong. Truck has just short of 170K miles & the harness has never been removed.

I haven't found anything specific on installing the harness onto the glow plugs. I'm guessing lube the o-rings & press on. Sound right?

Can somebody confirm the torque value on the glow plugs? I've seen 14lb/ft post on this forum.

 

I am looking into the DVD right now to see what it says for the 04

14 Ft/Lb is correct from what I read in the 04 early and late engine
book. If you replace any O-rings be sure to put a little clean engine
oil on them.

Sean

 

Thanks. Appreciate you looking that up.

 

Your welcome.
I was just doing an install of Final Cut Studio 3
on a Mac and it takes some time. You know the drill
Feed a disk in and wait, Feed in the next and so on.


Sean