Glow plugs 101 ***Ver. 2.0***

scooperhsd

Top Post Dawg
Joined
Aug 19, 2003
Location
Kansas City KS
TDI
NB, 2000, RED(5 Speed conversion) 2015 Golf SE
I just had this fight with MY 2000 NB -
make sure the glowplug harness is FIRMLY SEATED on the glowplugs - ALL of them - that's probably what is causing your problem. And I had replaced both the harness AND the glowplugs.
 

STRANGETDI

Veteran Member
Joined
Sep 20, 2001
Location
East Hampton, CT
TDI
2013 Audi A3 S-Line Premium Plus Quattro - APR Stage II
Check your harness too. It may be corroded or burnt through like mine was.
I haven't reset my CEL yet but, when I do, I hope this was the answer.

STRANGETDI said:
Here is why I replaced my harness:





I don't know what happened to it but I saw it as a problem.
Something either got fused to the harness or something melted through.
 

spoilsport

Top Post Dawg
Joined
Oct 3, 1999
Location
Houston TX
TDI
2000 Golf GLS Silver (Sold). 2005 Jetta TDI Wagon Tiptronic (daughter's)
Replacing harness

I need to replace the GP harness on my 2000 Golf. The boot around GP 1 is cracked, I suppose it just melted through. Anyway:

I've got two concerns about doing this myself. I warn you, they are stoopid. My experience in this area is limited to uhhhhhhh..........hooking up stereo speakers. :eek:
  • In the past while using wire strippers to prepare for a splice, I've not only stripped the insulation, but cut the friggin' wire as well. Any tips on avoiding this?
  • What is the worst case scenario here? A no-start?
Other than those concerns, this looks like cake! :D
 
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Venturabass

Veteran Member
Joined
Jun 24, 2004
Location
Stonington, CT
TDI
2001 VW Jetta TDI GLS, tornado red, 5spd
Great write up...I happened to throw an engine light about a week ago on my 2001 Jetta w/63K. Scanned w/ vag-com and it was good ol' P0380..I KNEW IT! Ran through the checklist in this thread, and my results were as follows:

all GPs registered 1.1 ohms, except the 3rd in from the left...after several minutes with the multimeter, i still couldnt get any reading at the tip of the plug. If I moved it down to the base, I could briefly get .4 or .5. Everything else checked out fine, and I even threw a little Deoxit D5 on the harness. Thanks again for this thread!
 

NorthernMage

Veteran Member
Joined
May 5, 2005
Location
Victoria, BC
TDI
2012 Jetta TDI, 6MT, Platinum Grey
My CEL came on this fall and I had it read, it was 0671 so the #1 Glow Plug. I read the thread and realised it wasn't cylinder 1 but the first glow plug in the circuit. Got out the voltmeter and read all the plugs, they were all .6 ohms except the first one which was infinite. Hauled it out and it was all covered in soot. Replaced with a Bosch OEM plug from NAPA and put some dielectric grease on on all the plugs, just a dab. Seems good now but I have to get the CEL reset next time I have a moment.
 

TravisG

Active member
Joined
Nov 9, 2000
Location
Salt Lake City, UT, USA
If the plug is covered in soot, does that mean it's absolutly bad? Has anyone ever seen a bad connection from the harness cause the plug to fail?

I noticed today, cleaning off the soot and reinstalling seems to return the plug to a normal reading. It made me wonder if the bad plug was actually ok.
 
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usedtdi

Member
Joined
Jan 30, 2006
Location
Lowell MI
TDI
2000 Jetta
Glow plug problem

I have a 2000 TDI and recently had the MIL light come on and found code 0380 was active. I followed the troubleshooting in the glowplug 101 section and found I had a glow plug with about 200 ohms of resistance. I replaced that glow plug and the MIL light still comes on. Do I have to reset the ecm to get the light to go out or do I still have a problem? I have checked the relay, fuses, and voltage to the glow plugs and all are ok. Any suggestions?
 

spoilsport

Top Post Dawg
Joined
Oct 3, 1999
Location
Houston TX
TDI
2000 Golf GLS Silver (Sold). 2005 Jetta TDI Wagon Tiptronic (daughter's)
usedtdi said:
I have a 2000 TDI and recently had the MIL light come on and found code 0380 was active. I followed the troubleshooting in the glowplug 101 section and found I had a glow plug with about 200 ohms of resistance. I replaced that glow plug and the MIL light still comes on. Do I have to reset the ecm to get the light to go out or do I still have a problem? I have checked the relay, fuses, and voltage to the glow plugs and all are ok. Any suggestions?
You just need to clear the fault code.

In the unlikely scenario that doesn't work, you should treat the GP harness to a little DeOxit, Stabilant, or contact enhancer of your choice.
 

Wingnut

Top Post Dawg
Joined
Oct 10, 2002
Location
Toronto & Whitby
TDI
Silver 2003 Jetta Wagon
Doug Huffman said:
On early TDIs the current comparator in the module of the GP relay may be too sensitive. Apparently that is cured by the use of dielectric grease though .
Just to let you all know, I do not recommend using dielectric grease in the glow plug harness if it is an old harness. If there is corrosion or oxidation in the harness, you are just insulating it with the grease. Its ok to use dielectric grease on a new harness or one that has been treated as it will prevent future corrosion. Just make sure the harness is good before using it.
 

WI_Norskie

Veteran Member
Joined
Dec 3, 2004
Location
Oregon, WI
TDI
2000 Jetta Galactic Blue
Done it all!!!!!!!

I've had a P0380 code since I bought my 2000 Jetta a year ago, and as my title says I've done it all to try to clear the code.

previous owner had the harness replaced 1 yr 6mo ago
my attempts:
cleaned contacts in harness
used copper antiseize in harness
cleaned contacts and traded glow plug relay with another TDI owner
replaced glow plugs
replaced harness (soldered connections)
disconnect and reseat connections to ECU
cleaned GND contacts at engine and under battery tray
replaced negative battery cable with new (helped starting turnover tho)


Where else should I be looking for ground connections?
Would another ECU be an option?

The ground connections are the point in the original post that I believe were over looked :confused: or, did I miss something?

Thanks for any other ideas.

Tryg

Oh, to be CEL free!!!!:rolleyes:
 

Doug Huffman

Veteran Member
Joined
Apr 7, 2000
Location
Washington Island, on the other side of Death's Do
TDI
Jetta Wagon 2K3 Silver gone to new home
Give JasonTDI a call. He's right up the road in Mad Liberal Town son. All else being okay, I (this being TDI-101 for newbies an' all) doubt an ECU will help other than the stealership's pocket. The error signal actually comes from the GP module's current comparator bridge and is sent to the ECU that's just doin' its job. Amongst your 'done it all', I didn't see that the DCT was reset.
 

WI_Norskie

Veteran Member
Joined
Dec 3, 2004
Location
Oregon, WI
TDI
2000 Jetta Galactic Blue
Yep, Jason scratches his head too.:)

I am understanding the DCT is the CEL code? I have Vag-com and have attempted to clear the code after every procedure. Sometimes it stays off until the next time I drive then it comes on after about 3 minutes (well after the glow plugs have been used), other times the CEL comes back on immediately.

As far as an ECU, the person I traded relays with has an extra one with an upsolute upgrade in it. Of course I may not give it back after "troubleshooting" with it.:rolleyes:

Thanks for the suggestions though.

Any other ideas are much appreciated.

Tryg
 

Wingnut

Top Post Dawg
Joined
Oct 10, 2002
Location
Toronto & Whitby
TDI
Silver 2003 Jetta Wagon
One thing to try is to bridge the 2 harness wires together. This will eliminate the possibility of the ECM detecting a variation in the plugs as they will all be on the same circuit instead of 2 seperate ones. If that fixes the CEL, then you know the problem is the plugs or the harness. If it doesn't fix the CEL, then the problem is between the harness & the relay.

It is a mickey mouse way of fixing the problem, but if you are not worried about monitoring the GP's, then you can leave the wires bridged and that will permenantly elininate the GP CEL. You will just have to check your plugs with a multimeter every fall before the cold temps set in to ensure they are OK so you won't have winter starting problems.
 

spoilsport

Top Post Dawg
Joined
Oct 3, 1999
Location
Houston TX
TDI
2000 Golf GLS Silver (Sold). 2005 Jetta TDI Wagon Tiptronic (daughter's)
what gauge is that?



Anyone know what gauge butt connectors to use? That looks like about.......16 gauge?
 

mdt

Veteran Member
Joined
Dec 19, 2002
Location
sunnyvale, ca
wingnut - one more huge thanks from this reader! three of my plugs read 0.5 ohms and the last was 26.5 on my '01. i was just going to replace them all. thanks for saving me $45 and showing me a new skill! -mt
 

kooyajerms

grocery getter
Joined
May 5, 2004
Location
Pomona, Southern California
TDI
97 B4V (mine), 11 x5 35d (hers) 04 V10 (that one you want), 2014 Q7 (mom's) 74 Shasta 1400
One thing to try is to bridge the 2 harness wires together. This will eliminate the possibility of the ECM detecting a variation in the plugs as they will all be on the same circuit instead of 2 seperate ones. If that fixes the CEL, then you know the problem is the plugs or the harness. If it doesn't fix the CEL, then the problem is between the harness & the relay.
I hate having to add more to this but at least it's a bump. 98 jetta

So yeah I put the wires all together so it's now a big fat gauge wire with all four wires together (I couldn't find a butt connector big enough so yeah it is pretty micky mouse and just mixed up together and shrink tubed. This is a brand new harness. I thought this would end any issue of resistance being read, but I'm still getting my 01050 - Intermittent Glow Plug Monitoring. CEL (cleared it yet again. It takes a good amount of time, and other times its the next day)
-I replaced the fuse that is behind the intake rubber boot. The strip metal one. Replaced the 20amp fuse thats right behind the battery.

Is it a relay issue for me also? Where do the A3 people go for that. I hate spending so much time on a CEL, but it sure is annoying that if I get a real one, I wouldn't be aware of it since the 01050 is always there.

Thanks guys.
Jeremy
 

spoilsport

Top Post Dawg
Joined
Oct 3, 1999
Location
Houston TX
TDI
2000 Golf GLS Silver (Sold). 2005 Jetta TDI Wagon Tiptronic (daughter's)
kooyajerms said:
So yeah I put the wires all together so it's now a big fat gauge wire with all four wires together (I couldn't find a butt connector big enough so yeah it is pretty micky mouse and just mixed up together and shrink tubed. This is a brand new harness. I thought this would end any issue of resistance being read, but I'm still getting my 01050 - Intermittent Glow Plug Monitoring. CEL
Re-do it with 12 - 16 gauge butt connectors. I had the #16 and it was a bit difficult to get all the strands inside the crimp. I heat shrunk the connection and haven't had any issues for 4 weeks now.
 

kooyajerms

grocery getter
Joined
May 5, 2004
Location
Pomona, Southern California
TDI
97 B4V (mine), 11 x5 35d (hers) 04 V10 (that one you want), 2014 Q7 (mom's) 74 Shasta 1400
with what wingnut recommended, #16 is more to do the normal connection, two wire to two wire. I'm joining all of them to become one wire. But I still don't think it's gonna change it. If anyone's done something with the relay..
 

bshieldsKC

Active member
Joined
Dec 13, 2005
TDI
2001 Jetta TDI 85,000k
Quick question.
It's been said to use dielectric grease on glow plugs. I'm a novis when it comes to this stuff and want to make sure before doing anything. Would you just removed the harness and apply some to the glow plug ends and replace harness? Thanks,
 

Wingnut

Top Post Dawg
Joined
Oct 10, 2002
Location
Toronto & Whitby
TDI
Silver 2003 Jetta Wagon
I do not recommend using dielectric grease on an untreated harness. All you are doing is trapping the corrosion behind a layer of grease. Dielectric grease is a good product to use for a new or already treated harness as it will seal the connection & prevent the oxidation from happeneing.

As for application, just pull off the harness and squeeze a blob into each hole. The grease will spread itself out as it is pushed back on to the plugs.
 

danbone7

New member
Joined
Mar 21, 2006
replace all glow plugs?

Real Quick Question. I've been reading these posts for sometime now and have been amazed in the effort put in. I have a CEL on and the dealer said I have 1 bad glow plug that is triggering the CEL. They also said I needed to replace the busbar and the injector return line since it would have to be taken off. The estimated cost for just replacing one glow was 550 and for replacing all 4 was 750. I've decided to try and do it myself and was wondering if there is any opinion on whether I should go ahead and replace all 4 glow plugs at the same time or only replace the one that is bad? Any advice on this issue would be great!
 

rdkern

Top Post Dawg
Joined
May 21, 2004
Location
Humboldt Co CA
TDI
Passat 1997 silver (sold after 11 years), Jetta 2000 atlantic blue
How many miles on the set? If over 100K, I'd replace them all, since they may be towards the end of their lives (last 100K anyways) and you'll have to pop off the harness whenever you have to do it again. The more often you remove the harness, the closer it is to being broken.

If less than 100K, just replace the one that's bad.

Replace the return lines? I don't recall that being necessary..... This is like a 1 hour job if you've never done it (and don't strip any threads..... WATCH OUT in putting the new one it - carefully get it started and torque only to about 11 ft/lbs). $550? I'll do it for you for only $450! (actually I'd help for the conversation). You'll need the deep socket 10 mm socket and some patience.
 

tdi_allan

Veteran Member
Joined
Feb 14, 2003
Location
Chicago, IL
TDI
2003 Jetta Wagon, 2003 Jetta Sedan (Lemons racer), 2010 Touareg
The common wisdom here is that glow plugs are highly user serviceable parts on TDIs. If you have replaced spark plugs on a gasser, these are pretty much the same. Replace the injector return line? Give me a break. Maybe if they always break them while taking everything apart. Anyway, assuming the busbar is the glow plug harness, you can get a set of GPs and the harness for around $100. Even if you follow my meticulous replacement procedure, it takes a rank amateur a couple of hours tops. Honestly, these dealers have not one bit of shame.

That said, I have replaced a total of two glow plugs on my car, the last in February 2005. They have been fine for over a year in the relatively mild Chicago winter. Also added dielectric grease to the glowplug end of the harness at that time. No glowplug faults so far, but I might replace them all before next winter as a preventative measure.

If we knew where you were, you could be pointed in the direction of competent alternatives to the, uhhhh, highway robbery that your local dealer is proposing.
 

Wingnut

Top Post Dawg
Joined
Oct 10, 2002
Location
Toronto & Whitby
TDI
Silver 2003 Jetta Wagon
Considering you can buy 4 new plugs for $60 shipped, why not replace them all? You will be saving yourself $690 from the dealer cost. As for the bus bar aka harness, just buy a $12 bottle of Deoxit D5 and that should be sufficient to treat your harness. If not...well...it was only $12. But out of the dozens of glow plug codes I have diagnosed & repaired for people.....I have only ever had to replace 1 harness.
 

spoilsport

Top Post Dawg
Joined
Oct 3, 1999
Location
Houston TX
TDI
2000 Golf GLS Silver (Sold). 2005 Jetta TDI Wagon Tiptronic (daughter's)
danbone7 said:
They also said I needed to replace the busbar and the injector return line since it would have to be taken off.
No need to remove any fuel line. Likely no need to replace harness. Dealers lie.

The estimated cost for just replacing one glow was 550 and for replacing all 4 was 750. :eek: I've decided to try and do it myself
Good decision!! :D

After you do this sucessfully, and you will, you'll think long and hard about returning to any dealership, least of all, that one!!
 
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WI_Norskie

Veteran Member
Joined
Dec 3, 2004
Location
Oregon, WI
TDI
2000 Jetta Galactic Blue
Follow up with solution I found

I thought I would report back what my final solution was with the P0380 intermittent CEL from hades.
I got under the dash again and after removing the relay from the socket I removed the socket from the holder. This allowed me to get just the wire bundle in hand for that relay. Then with a careful snip of the wrap loom, I started unwrapping the sticky tape back about 6 inches. Once I could separate the wires I started from the socket and found the green wire connection in the socket was loose and not staying where it should. A little gentle bend on the catch tab and it went "click" into the socket. After clearing the code I've been enjoying a CEL free life for the past few days.:)

Happy motoring,
Tryg
 

philh

Veteran Member
Joined
Dec 14, 2000
Location
Houston, TX
TDI
2003 Jetta Wagon
Thanks to all for the instructions. I was showing a bad plug on #4 for about 6 mos now and I finally got around to diagnosing (inspection was due). After all the checking, some DeoxIT (from Radio Shack) on the harness connectors did the trick.

cheers,
Phil
 

wny_pat

Top Post Dawg
Joined
Apr 7, 2004
Location
Western New York State
TDI
2002 Jetta TDI
Got some RS oxidation cleaner and did mine this afternoon. Number 3 connection was really dirty. CEL code indicated number 3 gp. Hopefully it will solve the problem for the time being. Computer showed it had come on 3 times total for number 3 gp. It was the only connection I got black gunk off of. Wonder why only one was dirty? Maybe to keep one coming back?
 
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