Glow Plug Circuit Malfunction...

spoilsport

Top Post Dawg
Joined
Oct 3, 1999
Location
Houston TX
TDI
2000 Golf GLS Silver (Sold). 2005 Jetta TDI Wagon Tiptronic (daughter's)
Your gonna continue to get the MIL, until it's cleared. That was my experience when I got the same DTC readout and replaced a bad glow plug. The CEL still came on, until I cleared it with VAG-COM.

You can continue to drive the car, but I'd recommend getting a VAG-COM and getting to the bottom of this.
 

GoFaster

Moderator at Large
Joined
Jun 16, 1999
Location
Brampton, Ontario, Canada
TDI
2006 Jetta TDI
Also keep in mind when checking for voltage at the glow plug harness, that this measurement needs to be done when the ECU is trying to turn on the glow plugs ... in other words, during the glow plug delay period after you switch the key "on".

The purpose of disconnecting the temp sensor is to extend this glow plug delay period to about 20 seconds, to give you a better chance at being able to make the measurements.

Gotta switch on the key and make the voltage measurements real quick.
 

gardentender

RIP, Gone But Not Forgotten
Joined
Feb 17, 2000
Location
Dullest Texxus
TDI
Jetta GL 5 spd, 2001, Galactic Blue
GoFaster,
how do you do the speedee voltage check/ignition key twisteroo all by yourself?
is there a clue in your "nom de net"??
 

SAC

New member
Joined
Aug 7, 2002
Location
Lawton, OK
GOfaster: I understand the purpose of unplugging the coolant sensor... but WHERE is it? Is it just the one on the resevoir tank?

I had autozone clear the code for me, and so far.. the MIL hasnt been back. Time will tell if the problem is gone or not!

GardenTender: My multimeter has deceint length leads on it, so I can set the meter on my windshield facing into the cabin while have the leads attached to the plug and contact so I can see the reading while in the drivers seat.
 

spoilsport

Top Post Dawg
Joined
Oct 3, 1999
Location
Houston TX
TDI
2000 Golf GLS Silver (Sold). 2005 Jetta TDI Wagon Tiptronic (daughter's)
The ECT sensor is on the back side of the block, drivers side, just behind and below the vacuum pump. At least, that's where it is on my MK-IV Golf.
 

The Kid

Veteran Member
Joined
Jul 18, 2002
Location
Oklahoma
The yesterday my MIL came on... had the code pulled at Autozone and it was for Glowplug/Heater Circuit "A" malfunction. The car starts and drives fine and the light is steady, not flashing and only comes on after the engine has been running for 30sec

So today after reading through some past posts I checked the resistances of the glowplugs, all 4 were .5ohms and the coolant plugs were .6ohms.

I cleaned the connections and hooked everything back up... still got the MIL. So i tried unplugging the plug connectors again and seeing if they were getting any voltage. I hooked up my multimeter between the connector and the plug but I can see no voltage going to the plug when the key is in the on position. I've seen mentioned somewhere that the coolatnt sensor needs to be disconnected to get a voltage reading, but where is the coolant sensor on a 01 jetta? Unfortuntly my car didnt have owners manual and I havent found a Bently manual yet. To my knowledge there isnt anyone with a VAG-COM around here to help me out.

I understand that the relay is under the dash, but is there anyway to check it to determine if it needs replacement? What else can I check? And is there a prefered way to clean the connectors?

Finally, is there any problem driving the car until I get this glowplug problem figured out?
 

Steve Addy

Top Post Dawg
Joined
Aug 7, 2002
Location
Iowa
TDI
97 Mk3
Hey
Did AutoZone clear the fault code and if so how long was it before it came back? I had mine checked today and got the same "380" Glow plug heater "A" circuit malfunction. They cleared the codes and I've driven for around 5 miles just getting back home and no mil light.

I'm curious about whether yours came back right away or not.

thanks
steve a
 

The Kid

Veteran Member
Joined
Jul 18, 2002
Location
Oklahoma
No problem, After they pulled the code, I did some searching on here and went about testing my glowplugs and cleaned there connectors real good. Then I had the code cleared and so far.. still hasnt returned! Heh, course I dont think my glowplugs are too necessary when its 110*F+ here!

But ya, so far and no MIL return... hope it stays that way for both of us!

Brian
 

spoilsport

Top Post Dawg
Joined
Oct 3, 1999
Location
Houston TX
TDI
2000 Golf GLS Silver (Sold). 2005 Jetta TDI Wagon Tiptronic (daughter's)
Originally posted by The Kid:
No problem, After they pulled the code, I did some searching on here and went about testing my glowplugs and cleaned there connectors real good. Then I had the code cleared and so far.. still hasnt returned! Heh, course I dont think my glowplugs are too necessary when its 110*F+ here!

But ya, so far and no MIL return... hope it stays that way for both of us!

Brian
<font size="2" face="Verdana, Helvetica, sans-serif">It's plenty hot in Houston as well, but I didn't escape a bad glow plug on the wife's Jetta. Some of the brainier people probably know, but I suspect that even under mild conditions there may be an afterglow period, following the non-existent pre-glow period that would keep the GPs in use. Isn't the afterglow supposed to help a "cool" engine keep emissions in check until it reaches operating temps?

Anyway, I got the same code, did the same research on this excellent forum, and avoided a trip to the dealer !
 

milkman

Well-known member
Joined
Apr 27, 2001
Location
Abbotsford, B.C. , Can.
I had a similar occurance a few months back. Dealer replaced the glow-plug wiring harness and connectors and problem was solved. Their readout showed "resistance variation". Hope this helps.
 

saabguru

Veteran Member
Joined
Mar 4, 2001
Location
The Capital of the Great State of Texas
In an attempt to clear the cause of an illuminated MIL light, I removed and replaced the glow plug harness- couldn't disconnect it, it's hard wired to the bug round cannon plug on the end of the engine. Now I have a MIL AND a blinking glow plug light, after 45 seconds or so of operation. I'm thinking I damaged the harness in removing it- I rechecked the cannon plug and it's on tight.
 

The Kid

Veteran Member
Joined
Jul 18, 2002
Location
Oklahoma
well, the MIL DIDNT stay away. It likes to come on every week or so. I'm getting a Vag-Com soon so I'll do some deeper troubleshooting then... until then I'm living with the MIL cause I got tired of going to AutoZone every week to get it cleared.

Saab: How is the harness replaced if it isnt disconnectable? Snip wires and solder on the new harness?
 

danix

Veteran Member
Joined
Oct 5, 2000
Location
Raleigh, NC
TDI
None now. Former: 2011 335d, 2010 Jetta TDI, 2003 Jetta TDI Wagon. 99.5 Jetta TDI, 98 NB TDI, 3 different black 96 Passat TDI wagons.
My light has been intermittent since we got the car. I havent replaced the harness yet but will soon, most likely.
 

vgordon

Well-known member
Joined
Sep 17, 2000
Location
FL, USA
TDI
Jetta, 2000, Green
My MIL came on Thursday on my way home from work. It's continuous and probably comes on about 30 seconds after start. The nearest AutoZone couldn't tell us what was wrong because their equipment couldn't read the newer VWs. I've noticed at least one message from an owner of a newer VW than mine, who received assistance from AutoZone. I haven't been able to reach anyone with a VAG-COM yet, and I am trying to get out of an expensive trip to a dealership - SO can anyone tell me if some AutoZones are equiped to read VW codes (and is there anything particular I should ask for when calling around?). Thanks!

2000 Green Jetta TDI
 

MOGolf

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Location
underneath something
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2001 Golf GLS TDI Reflex silver, rough road suspension and steel skid plate, 2004 Passat Variant, Candy White, rough road suspension and geared balanced shaft module, and much, much more. 2016 LR RR HSE TD6, 2019 Jaguar I-PACE
I had the same experience with an Autozone near here. They are all not equipped alike, be it equipment or people using the equipment. Ask them if they have a code reader for European vehicles with ISO-9141-2 interface capability. (They probably won't understand.) Suggest they look at the instruction book for their tool if they're unsure/don't know.
 

Dooldeniya

Well-known member
Joined
Feb 25, 2001
Location
Austin, Texas
I've had the same problem and had to replace a glow plug that was burnt. I used a continuity tester to test the glow plugs. All you do is connect one end to the positive terminal on your battery and touch the point to each glow plug. If the glow plug is good the tester should light up. I bought the glow plug replacement from the dealer for $44.

Good luch on your fixing.
 

vgordon

Well-known member
Joined
Sep 17, 2000
Location
FL, USA
TDI
Jetta, 2000, Green
Originally posted by MOGolf:
I had the same experience with an Autozone near here. They are all not equipped alike, be it equipment or people using the equipment. Ask them if they have a code reader for European vehicles with ISO-9141-2 interface capability. (They probably won't understand.) Suggest they look at the instruction book for their tool if they're unsure/don't know.
<font size="2" face="Verdana, Helvetica, sans-serif">Thanks
, I called a couple today and both said they could check ANY car since 1996 (or whatever date), I thought I would give it a whirl. But as I started driving there I noticed my MIL wasn't on anymore. After a few miles I just turned around, didn't know if they could do anything when the light wasn't on anymore? But at least I know what to look for if it happens again - and to keep checking AutoZones!
 

jimmyz

Veteran Member
Joined
Feb 27, 1999
Location
Kenosha, WI - former home of the late AMC
TDI
TDI Jetta GLS, '99.5, Silver Arrow, 2010 Jetta Salsa Red TDI Cup Edition w/DSG, 2 x 2016 TDI Touareg Execs
If you do a search of postings by my member number you will see some of the history I had with 7 trips to the dealer for glow plug codes. The problem was finally resolved by replacing the harness. All is still well after about 16 months, knock on wood.
 

morty

Veteran Member
Joined
Sep 11, 1999
Location
Sunny Arizona
TDI
00 Golf Silver
Does anyone know where I get the least expensive glow plug harness. Did VW make a change to the harnesses or will I have the same problems down the road with the new one??

Best regards,

Morty
 

jimmyz

Veteran Member
Joined
Feb 27, 1999
Location
Kenosha, WI - former home of the late AMC
TDI
TDI Jetta GLS, '99.5, Silver Arrow, 2010 Jetta Salsa Red TDI Cup Edition w/DSG, 2 x 2016 TDI Touareg Execs
I'm just going on memory here but I think the part was around $30 from the dealer. I don't have my invoice or the part number. At one time they were out of stock in the US distribution. I think I was told that new parts were improved, there had been a common problem of intermittent opens.
 

tongsli

Top Post Dawg
Joined
Jan 31, 2000
Location
Baltimore, MD
TDI
2000 Jetta TDI, 2004, Jetta Wagon TDI PD
The glow plug harness should cost you about $20.00.

The part number is:

028 971 766

L
 
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