Glow plugs and wiring harnesses

BKH · **Posted:** Tue May 09, 2006 7:45 pm

At 8,000 miles, the CEL appeared - first time ever. Everything was running fine, so I wasn't too worried. I took it in to the dealer on Friday. They called, saying it was a bad glow plug and that they'd have a replacement to the dealership by 3pm that day. At 4pm, they called and said the replacement glow plug was also bad. Monday they called and said it appeared to be a faulty wiring harness that was fouling the glow plug and that a replacement harness would not be in until Wednesday.

This is my first problem with the CRD, so the delay / process of elimination diagnosis has me a bit frustrated right now.

Hopefully I will have it back tomorrow. Hopefully....

Ranger1 · **Joined:** Mon Oct 17, 2005 7:40 pm **Posts:** 1137

Ask your dealership tech how they determined the gp harness is bad. If they used an ohmmeter from the connector to the plug, they'll see an open if they check either gp#1 or gp#4. Reason? The 4 individual wires from the gp connector to each gp are all black, unmarked and on mine, #1 and #4 were switched at the factory. The wire from the connector pin labeled gp#1 was actually run to cylinder #4 and vice versa. If you look at the connector and wires, you'll see it would be a very easy mistake to make on the factory line.

When I had a P0671, gp#1 bad, the tech replaced #1 and the fault didn't clear. It took some checking from the connector to the wiring harness plug to see what happened. When the tech called STAR, they already knew the gp wiring harness was switched on 1 and 4. It doesn't really hurt anything, except when you have a code set and need to replace one.

Another thing to check is to see if your dealership tech knows these glowplugs are the latest, ceramic tipped 7 volt dc type. The instructions say not to touch the ceramic tip with your fingers, as the oil on your fingers can cause premature burnout. Also, if the tech is used to applying battery 12 volts to test them, he just burned it out. Most previous glow plugs were 12 volts - thats why the yellow warning on the timing cover on the engine of the CRD.

BKH · **Posted:** Tue May 09, 2006 8:30 pm

Thanks, Ranger. I'll ask when I talk to to the service department tomorrow. I know they had to call STAR about the issue, but I don't know more than that at this time. Your information is awesome - it's always good to be armed with as much knowledge as possible. More later....

RTStabler51 · **Posted:** Wed May 10, 2006 12:30 am

I had a bad glow plug at 8k as well...hmmm, they seem to all be #4...

BKH · **Posted:** Thu May 11, 2006 7:28 pm

Well, here's the latest update. The wiring harness was delayed by a day. Now it's here and STAR wants the dealer to replace ALL glow plugs before giving the CRD back to me. The dealership, Elway Jeep, has been great - calling me every day with updates and being extremely apologetic about the delay. I assume that replacing all the glow plugs is good news, rather than just giving it back with a replacement for the one failed plug and a new wiring harness.

Does anyone have any thoughts on all this? Does this all sound legit?

Ranger1 · **Joined:** Mon Oct 17, 2005 7:40 pm **Posts:** 1137

I think it's better to replace all 4 just to have them age at the same time. It might end up saving you multiple trips if another gp dies in a few months. It probably costs Chrysler less to replace them all at once on labor charges. From the number of failures, it sounds like some weak gp's were shipped out. Some TDI owners are experiencing the same early failure rate on these newer gp's. Having just bought a set of 4 replacements, I notice that Bosch changed the shape of the ceramic tip on the new ones.

BKH · **Posted:** Sat May 13, 2006 12:16 pm

I got it back yesterday. Here's the sccop according to the receipt. The writing harness had the wires for #2 and #3 glow plugs reversed. The fault code said #2 was faulty, but it was actually #3 - inaccurate fault code because of the reversed wires for #2 and #3 in the harness.

All plugs were replaced with the new design, and all software was updated. Hopefully this does it!!!

Flying J · **Posted:** Sat May 13, 2006 1:14 pm

Mine ate the #4 at 9000, the #2 at 9300, and the #3 at 10000. When they replaced #3 they also replaced #1. Thats been about 200 miles now so I'm keeping my fingers crossed...

-Vic

RTStabler51 · **Posted:** Mon Aug 07, 2006 10:31 am

Is there a way for us to figure out which wire is to go to which glow plug? I'm having the 3rd glow plug replaced, I'm not sure which specific one, but I've already had 1 & 4 replaced...

retmil46 · **Posted:** Mon Aug 07, 2006 10:45 am

Week ago had #4 replaced, month after EGR replacement. Today going in because either #2 or #3 is bad.

I'm going to bring it up to them, I'll pay for the other two if necessary, let's just get them all changed out now so we don't have to repeat this evolution, one plug at a time.

RFCRD · **Posted:** Mon Aug 07, 2006 11:09 am

retmil46 wrote:

Week ago had #4 replaced, month after EGR replacement. Today going in because either #2 or #3 is bad.

I'm going to bring it up to them, I'll pay for the other two if necessary, let's just get them all changed out now so we don't have to repeat this evolution, one plug at a time.

Has anyone figured out why the GP's fail? Fortunately I haven't had any problems with GP's (or EGR) but they seem fragile for their application. Just wondering with the wires crossed from the factory if the tech's can't figure it out with the computer. Then start poking around with a 12v test light or meter and damage something?

Ranger1 · **Joined:** Mon Oct 17, 2005 7:40 pm **Posts:** 1137

Quote:

Has anyone figured out why the GP's fail?

No, but I notice that the gp's you can buy now for the CRD are different in the shape of the ceramic tip than the OEM's. The originals had a rocket cone shape - the new ones have a squarish stick shape. Something drove the change.

Rebuilding our CRD's one gp at a time...

Glow plugs and wiring harnesses

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