Glow Plugs from Hail!

WDP

Veteran Member
Joined
May 20, 2006
Location
Eastern Pa
TDI
1998 A3 Jetta- 2000 A4 Jetta- 2003 A4 Jetta, 2001 NB
Yes I have read 101 and 102. Vehicle, 2000 Jetta- 2 wire harness. I have replaced all glow plugs with Bosch, the harness was eliminated, soldered 14 gauge marine stranded wire right from the GPs to the two wires where the old harness was cut out. Even soldered the two leads together as suggested to prevent the ECU from seeing any difference between the two legs. Checked the 53 and 100 relays for operation and contact resistance, all good, cleaned socket contacts with DeOx it. Glow plug system, voltages and timing all check out. Car starts fine but the P0380 fault is still there. Winter is coming and this thing has been bugging me for 3 years (no diesel emissions in Pa.) What am I missing? Maybe some other connectors between the glow plug ex-harness and the relays, maybe dirty connections at the computer? How does the ECU know the GPs are working? Time to put this VW electricial headache to bed. Thanks for your help.

WDP
 

Dimitri16V

Top Post Dawg
Joined
Jan 30, 2005
Location
DE
TDI
01 Golf, 04 Golf
find the connector in the harness and clean the contacts on that too.
add some ground wire straight from battery to engine block/head.

the CEL will still come on though , it's stupid software
 

turbocharged798

Veteran Member
Joined
May 21, 2009
Location
Ellenville, NY
TDI
99.5 black ALH Jetta;09 Gasser Jetta
Bridging the two wires together should eliminate the CEL forever. If it still come back. something is seriously wrong in the system.

I did the wire bridge mod on my 99.5 because I got so tired of the stupid P0380 and no more cel after that. I wouldn't do it if the system actually worked, but the glow plug monitoring system used in these cars is crap.
 

WDP

Veteran Member
Joined
May 20, 2006
Location
Eastern Pa
TDI
1998 A3 Jetta- 2000 A4 Jetta- 2003 A4 Jetta, 2001 NB
find the connector in the harness and clean the contacts on that too.
add some ground wire straight from battery to engine block/head.

Is that the one between the relays and the harness in the wire run under the air cleaner box? Grounds were all cleaned, but more is better. Thanks
 

BlackSunshine

Active member
Joined
Sep 11, 2008
Location
B.C. Canada
TDI
Tdi 1.9L ALH
Misery loves company.

I am battling a very similar problem. Have had it since I've owned the car (about 6 months), so I don't know how long it has been doing this. Like you, winter is coming and I want to resolve this issue before frosty comes. A simple 2-wire system like this? An easy fix.This isn't rocket science.

Or so I thought.

The seemingly simple problem I am battling is that the glow plugs don't stay on long enough. The glow plug light comes on and goes off in about 1 second (or less). Doesn't matter if it is hot or cold. When it IS cold, it requires 2 - 3 cranking sessions to get 'er to fire. I know this isn't right.

When I pull the plug to the temp sensor, the glow plug light stays on for 10-12 seconds. I am only asking for maybe 3-4 seconds when it is cold... Is that too much to ask!?!?:rolleyes:

I've been through the 101 and V2 and saw a ton of great advice, and followed may of the suggestions, but still haven't hit the nail on the head.

I've had the P0380 coming on constantly over the last week or so - had never really done that before. I was resetting CEL each day, sometimes multiple times per day,(sometimes ignoring it) but it was always the same code. I finally received my new harness. After installing the harness, I found that the previous owner/mechanic had done the 'join the wires together' modification. I decided to put the harness back to OEM configuration with each wire soldered and shrink wrapped and hoped for the best. So far I don't have a CEL any more (3 days and counting), but I don't think the problem is resolved either. The GPL stays on for the same amount of time, and the starting really isn't any (noticeably) better.

I can still pull the temp sender and get a good 10+ second glow out of it, so I know the system integrity is fine - it seems like it is just not getting the 'signal' to glow longer than a flash. (Or is being told to stop?)

Yes, I tried the VAG-COM glow time extension mod, but it didn't yield any results either. Still just a short 1 second 'blip' of GPL.

I have access to a shop, a VAG-COM, the car is parked in a garage (been parking it outside to try and keep it 'cool'), has a pan heater, and I have another vehicle I can drive if something goes sideways on a repair. It's not that I am in a panic to fix this issue, it's more like I am on a MISSION to fix this issue.
 

kwong7

Veteran Member
Joined
Mar 25, 2004
Location
Southern Caifornia
TDI
2001 Golf GLS TDI / White
We just fixed my buddy's 99.5 Jetta TDI. His registration is due later this month and needs to get smogged. Unfortunately, the CEL came on about 2 months ago. We scanned the system and was informed that the glow plugs system was getting an intermittent signal. You may want to try clearing the codes through the "Select Control Module," -> "Engine," -> "Fault Codes," then "Clear." For some reason, this method worked, while the "Auto-Scan" route did not work the first time. See below for the full details.

First we tried Deoxit on the harness and cleared the codes using auto-scan. About a mile later, the CEL flashed back on. Next we checked the resistance of each glow plug. We discovered that one plug was not giving a reading. We replaced that plug and went on to test the harness. We unplugged the coolant temp sensor harness, turned the car on (not start) and test each harness terminal. Each read 12.48V, so we ruled it out. Finally, we checked the fuse cluster above the battery.

After doing an auto-scan and clearing the DTCs, we drove to lunch. About a 1/4 mile down the block, the CEL came on again. This time we got the glow plug AND the CTS sensor showing an error. We discussed our frustrations over lunch and gave it one more go after our meal. Instead of running the auto-scan feature on VCDS, we went to the engine menu, then fault codes. We cleared the codes and everything has been great since. No more CEL.
 

cleaver

Veteran Member
Joined
May 8, 2006
Location
Berwick, Nova Scotia
TDI
None - did own '01 and '02 Jetta TDI
BlackSunshine---
If you have only owned the car for 6 months, it hasn't been cold enough for the Glow Plugs to stay on longer....My GP light only stays on for a second unless it is below 0C...it is temp dependant, even when it was (-20C) the GP light was only on for a couple seconds...
 

BlackSunshine

Active member
Joined
Sep 11, 2008
Location
B.C. Canada
TDI
Tdi 1.9L ALH
BlackSunshine---
If you have only owned the car for 6 months, it hasn't been cold enough for the Glow Plugs to stay on longer....My GP light only stays on for a second unless it is below 0C...it is temp dependant, even when it was (-20C) the GP light was only on for a couple seconds...
It was quite cold last night, rainy and miserable. Maybe around 5C or something. I left the car outside overnight, and tried it again this morning. To my surprise, the GPL stayed on for about 3-4 seconds, and the car started better than it has in the past. (meaning only 1 cranking session to get it started, not the 2 or 3 that I am used to doing.)

I agree that maybe it just isn't cold enough yet to activate the glow plugs for any longer than a couple of seconds, and I really haven't owned the car long enough to get some good solid cold winter starts out of it. I am certainly pleased that the light 'seems' to be staying on longer, but I guess it is just a matter of time (and temperature!) until I can confirm it is repaired for sure.

It has been 5 days now without a check engine light, or P0380 code.

Fingers are still crossed.:eek:
 
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JB05

Top Post Dawg
Joined
Oct 20, 2005
Location
Il.USA
TDI
Golf,2005,anthracite blue
FWIW, the GP light is not an indicator of the actual GP activation. Mine is on for a few seconds, but the GP's are on for as long as 23 seconds, depending on temperature. Once the engine is started the after glow can last anywhere up to four minutes, but I'm not certain what determines the duration of this AG. I installed a pilot light so I can actually visualize all of this.
 

BlackSunshine

Active member
Joined
Sep 11, 2008
Location
B.C. Canada
TDI
Tdi 1.9L ALH
FWIW, the GP light is not an indicator of the actual GP activation.
Well, now I am curious...

If that is the case, why does the GPL come on for varying lengths of time, usually depending on temperature?

Why does un-plugging the temp sensor change the amount of time the GPL is on?

Afterglow is not my concern, pre-start glow time is what I am interested in finding out more about.
 
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JB05

Top Post Dawg
Joined
Oct 20, 2005
Location
Il.USA
TDI
Golf,2005,anthracite blue
Sunshine, my GPL varies also; Summer is a couple seconds duration and Winter it is maybe 5 or 6. Again the GP's themselves are still on regardless of the GPL according to my pilot light. I have no idea what the logic is with these GP's, but mine is a BEW.
 

BlackSunshine

Active member
Joined
Sep 11, 2008
Location
B.C. Canada
TDI
Tdi 1.9L ALH
Sunshine, my GPL varies also; Summer is a couple seconds duration and Winter it is maybe 5 or 6. Again the GP's themselves are still on regardless of the GPL according to my pilot light. I have no idea what the logic is with these GP's, but mine is a BEW.
I certainly appreciate your response, but I just can't get my head around accepting that there is no rhyme or reason for the GPL staying on for a short time or a long time... These cars aren't wired with magic.

I will keep investigating - thanks for your reply.
 

cleaver

Veteran Member
Joined
May 8, 2006
Location
Berwick, Nova Scotia
TDI
None - did own '01 and '02 Jetta TDI
... These cars aren't wired with magic.
You do realize that you are driving an exquisitely engineered german VW?

I think the GPL does show a simplified duration time for the actual GP pre-heat. If the GPL is short, the GP glow is short (but longer than the GPL). If the GPL is longer, the GP glow is longer (and longer than the acutal GPL).

I hope that is clear as mud...
 

BlackSunshine

Active member
Joined
Sep 11, 2008
Location
B.C. Canada
TDI
Tdi 1.9L ALH
You do realize that you are driving an exquisitely engineered german VW?

I think the GPL does show a simplified duration time for the actual GP pre-heat. If the GPL is short, the GP glow is short (but longer than the GPL). If the GPL is longer, the GP glow is longer (and longer than the acutal GPL).

I hope that is clear as mud...

Thanks for the note - I certainly appreciate your help, but this seems to be problem I am having:

"I think the GPL does show a simplified duration time for the actual GP pre-heat."

I can appreciate your opinion, but I am looking for some facts. Is this something that you KNOW to be fact? Basically, you're stating the GPL is an estimation of the time the glow plugs are activated? Have you verified this with a knowledgeable technician, a shop manual, or first hand experience?
 
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cleaver

Veteran Member
Joined
May 8, 2006
Location
Berwick, Nova Scotia
TDI
None - did own '01 and '02 Jetta TDI
nope, just 500,000km of driving...on only one VW.

The only thing I notice is that as it gets colder, the GPL stays lit longer. From what others say on these forums, the GP glow longer than the light is on. No other scientific evidence other than my own two eyes...lol.: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
Hmm, talkin' about exquisite German engineering, I think a German invented the only tool that can reliably measure resistances less than one ohm, like our GPs. But all here seem to prefer an automotive expert to an electrical engineer on glow plug engineering.

A DVM or whatever ain't good enough.
 

BlackSunshine

Active member
Joined
Sep 11, 2008
Location
B.C. Canada
TDI
Tdi 1.9L ALH
nope, just 500,000km of driving...on only one VW.

The only thing I notice is that as it gets colder, the GPL stays lit longer. From what others say on these forums, the GP glow longer than the light is on. No other scientific evidence other than my own two eyes...lol.:rolleyes:
Thanks for the tip - I'll add it to my list.

I have a couple of calls into some friends that may be able to help out, an old friend who is now apparently running the service dept at a local VW dealership, and another who runs an independent euro auto repair shop.

I'll find out what I can and report back.
 
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