Glow plugs

danoid · **Posted:** Wed Jun 16, 2010 7:39 pm

Been having a check engine light for a while. I forgot the p-codes but the text associated was something like, 'Glow plug #1 circuit or plug fault' and 'Glow plug #2 circuit or plug fault'. No big deal it's summer right?

Service info says to...

1) try replacing the glow plug control module (looks like a relay on steroids). Backordered for two weeks, got it - no luck.

2) try replacing the ECM - no luck.

3) inspect wiring - no visible issues with wiring and I don't have the proper probes to check the engine side of the harness.

4) take it to dealer for new glow plugs.

Estimate was $220. Since taking out the front two glow plugs entails removing the alternator I said go for it.

Well...

Evidently it's a somewhat known issue that those particular diagnostic codes usually mean a problem not with cyl 1 or 2, but with cyl 3 or 4. A significantly more labor intensive process to remove and replace at $90 per hour. So I went back to the dealership prepared to give the usual righteous indignation flare about a bill suddenly tripling the estimate.

To my surprise, they swapped out #3 and #4 for $225. (Somewhat) happy me! At least I'm not out a complete fortune, and I would have been far more upset if I had done it myself and swapped out #1 and #2 only to find out the code was wrong!

Looking at the removed parts, it's a good thing they aren't in the combustion chamber any more...

I can only assume the disappeared pieces were ejected out the exhaust valve and are now clogging my cat.

BVCRD · **Posted:** Wed Jun 16, 2010 8:22 pm

At what mileage did this take place?

danoid · **Posted:** Wed Jun 16, 2010 9:12 pm

77,000 miles

CATCRD · **Posted:** Wed Jun 16, 2010 10:56 pm

That's what one of my glow plugs looked like when I pulled it. Danoid, can you remember if the codes first popped after moving the jeep a few feet and turning it off right away? Like less than a minute running?

danoid · **Posted:** Thu Jun 17, 2010 9:36 pm

No. Don't remember when. It was a couple of months ago.

Joe Romas · **Posted:** Sun Jun 20, 2010 5:55 pm

The reason the codes indicated 1 & 2 and actually it was 3 & 4 is because some if not all glow plug harnesses are put on backwards :banghead:

CATCRD · **Posted:** Sun Jun 20, 2010 6:18 pm

FWIW, my gp harness was on correctly.

ac5501 · **Posted:** Mon Jun 21, 2010 2:00 am

Joe Romas wrote:

The reason the codes indicated 1 & 2 and actually it was 3 & 4 is because some if not all glow plug harnesses are put on backwards :banghead:

Mine was most definitely on backwards

dirtmover · **Posted:** Mon Jun 21, 2010 10:04 am

Mine is correct also and FWIW all three that have been changed so far have been cracked from the tip to about 15mm down the length of the ceramic but no missing fragments.

Joe Romas · **Posted:** Mon Jun 21, 2010 12:10 pm

Do you all have the latest firmware (flash) in the ECM? Per GDE it's important for long glow plug life to have the latest :mrgreen:

danoid · **Posted:** Thu Jul 22, 2010 10:32 am

CATCRD wrote:

That's what one of my glow plugs looked like when I pulled it. Danoid, can you remember if the codes first popped after moving the jeep a few feet and turning it off right away? Like less than a minute running?

Definetly no. I suffered a long, stuttery crank, (took two tries to start up and then ran bad for a few seconds) drove 7 miles then shut it off. That afteroon the MIL was on and the code was Cylinder #1, harness or glow plug failure.

I remember now BECASUE IT EFFING HAPPENED AGAIN!

flash7210 · **Posted:** Thu Jul 22, 2010 10:55 am

Is there a prescribed interval for chaning the glow plugs?
Or do I just wait for a CEL or cold starting problem?

BVCRD · **Posted:** Thu Jul 22, 2010 12:54 pm

flash7210 wrote:

Is there a prescribed interval for chaning the glow plugs?
Or do I just wait for a CEL or cold starting problem?

The glow plugs stay on for longer than the dash light....like for 2-3 minutes. I turn my key on in the winter, wait 20 seconds then start it.

flash7210 · **Posted:** Thu Jul 22, 2010 8:38 pm

What I mean to say is, after how many miles should I consider changing all my glow plugs?

danoid · **Posted:** Thu Jul 22, 2010 8:51 pm

To my knowledge they are not a regular maintenance item. Looks like I, however, need to invest in a case of them. 1 month, about 1500 miles.

salden77 · **Joined:** Tue Jun 01, 2010 2:42 pm **Posts:** 271

are the glow plugs expensive? i wish they put a grid heater in the CRD like they do on the cummins.

bugnout · **Posted:** Thu Jul 22, 2010 9:35 pm

Wasn't there some talk of metallic gp's replacing the ceramic gp's in TDI's because they were failing in the same way?

Wonder if there is a suitable Metallic replacement model for the VM engine from Bosch?

danoid · **Posted:** Fri Jul 23, 2010 5:41 am

It's more than talk, it's 90% sure to be our future for replacement parts.

One caveat, it requires new engine software to run them.

warp2diesel · **Posted:** Fri Jul 23, 2010 7:39 pm

danoid wrote:

It's more than talk, it's 90% sure to be our future for replacement parts.

One caveat, it requires new engine software to run them.

Let me guess, it will trash our tunes at the same time.

Let me know if I am wrong, for once I hope I am.

GreenDieselEngineering · **Joined:** Sun Jun 07, 2009 5:10 pm **Posts:** 1111

Warp,

The new code required for fast metallic glow plugs will trash your tune. But this is easily remedied through your tune supplier. Bosch discontinued the ceramic glow plugs for a valid reason...they can catastrophically fail. When metallic glow fail, they may deform a bit, but not fracture and fall into the combustion chamber.

Glow plugs

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