Glow plug only stays on for a second then goes out?

veggieman

Veteran Member
Joined
Jan 1, 2008
Location
Sweet Home Alabama!
TDI
04 Golf
I was at my buddies house last week admiring his "new" A3 Jetta TDI. When he tried to cold start it his glow plug light came on for no more than a second, turned off and then as he went to start it, the Jetta turned over several timed before finally firing.

I walked over to my A3 Jetta to show him how it should work...I turned the key on, glow plug light came on for 2-3 seconds, went off and my TDI immediately fired, (as usual.)

Yesterday I went to cold start my A3 TDI and the glow plug light only stayed on for maybe a second and when I tried to start it the Jetta turned over 4-5 times before firing where it usually fires as I bump the key.

I did a search and only came up with the blinking glow plug light, which is not the issue here. Does anyone know what causes this? Very irritating!:mad: My A3 warms my heart every time I hear it pop off so easily and not it's embarrassing me!!

Thanks,
~Jason
 

heaveninbc

Member
Joined
Mar 1, 2008
Location
Longmont,CO
TDI
1998 VW BEETLE TDI
you are getting a bad connection from the power supply to the glow plugs at some point in the wiring.back track your wiring and see if you can find a grounging problem or a crappy connection.I hope this helps you-Daniel:)
 

veggieman

Veteran Member
Joined
Jan 1, 2008
Location
Sweet Home Alabama!
TDI
04 Golf
It's been hovering around the 40-45degree mark outside, plus it's been damp. Is the problem the ambient temperature, or the temperature sensor?

Am I correct to think there's more than one temp sensor? Which one controls the glow plug cycle?

Where's the power supply to the glow plugs? I'll trace that down as well. It doesn't sound very easy!!

Thanks again,
~Jason
 
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Lex4TDI4Life

Top Post Dawg
Joined
Jun 22, 2006
Location
NorCal
TDI
2001 Golf-Ute TDI GLS 5spd Manual
The glow plugs will kick in when the coolant temp is at 40 degF or less. This is most likely why you are not seeing extended glow plug times.

And yes, there are 2 coolant temp sensors. One controls the glow plugs and the other sends to coolant temp to your cluster gauge.
 

veggieman

Veteran Member
Joined
Jan 1, 2008
Location
Sweet Home Alabama!
TDI
04 Golf
Well, either I have an electrical issue, (improbable being a VW) or I have a bad temperature sensor.

The fact that the Jetta will no longer pop right off indicates an unacceptable problem.

Which sensor controls the glow plugs?
 

rdkern

Top Post Dawg
Joined
May 21, 2004
Location
Humboldt Co CA
TDI
Passat 1997 silver (sold after 11 years), Jetta 2000 atlantic blue
veggieman said:
Well, either I have an electrical issue, (improbable being a VW) or I have a bad temperature sensor.

The fact that the Jetta will no longer pop right off indicates an unacceptable problem.

Which sensor controls the glow plugs?
Coolant temp sensor controls the glow plugs.

However, have you checked the timing?
 

veggieman

Veteran Member
Joined
Jan 1, 2008
Location
Sweet Home Alabama!
TDI
04 Golf
Which temperature sensor controls the glow plugs?

Ever since I've owned this Mk3 the glow plugs have functioned correctly and the car has started up as soon as I bump the ignition. As of yesterday the glow plug light only stays on for a second, or less and the car turns over 4-5 times before starting when cold.
 
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rdkern

Top Post Dawg
Joined
May 21, 2004
Location
Humboldt Co CA
TDI
Passat 1997 silver (sold after 11 years), Jetta 2000 atlantic blue
There's one coolant temp sensor that has two readouts.

At 40-ish, the gps shouldn't be on much at all.

Other possibilities, battery going south, starter motor starting to show signs of age. Start getting stuff tested.
 

kilo69

Veteran Member
Joined
Jan 9, 2008
Location
Halifax, NS, Canada
TDI
2003 Jetta Wagon TDI, 98 Jetta TDI
When it's close the to GP threshold for temperture 40F then timing of the injection is critical.

It can be 41F and you'll have no GP assist and the timing needs to be PERFECT to get full combustion right away.

Likely the timing is not dead on. If it was 35F you'd probablly have no issue as the GP's would turn on and cover up the timing issue
 

veggieman

Veteran Member
Joined
Jan 1, 2008
Location
Sweet Home Alabama!
TDI
04 Golf
More details

I was preparing for nozzles and a chip install a few weeks back so the timing was checked at that point. It was found to be waaaaaaay retarded, but the TDI guru, (fellow member) could not believe it would start as well as it was and run as great as it did, so nothing was done about the timing.

See:
http://forums.tdiclub.com/showthread.php?t=204448

I just can't get over how the glow plug light comes on and immediately goes off when the engine is cold, or warm. I'm willing to bet the light doesn't stay on for even a full second.

Yesterday morning when I first had the issue the outside temperature was right at 40 degrees. Glow plug stayed on for <1 second and the car had to turn over 4-5 times before firing. When it did fire...it ran fine.

Early afternoon temperature was mid 50s and the exact same thing happened as earlier.

Late last night around 11PM, temperature was back in the lows 40s and the same issue occured.

This morning, temperature right at 40...same issue.

Now...when the car is warmed up the glow plug light does the same thing, (on and back off very fast) but the car fired up like it should.

It's sounding like a temperature sensor to me?? :confused:

I appreciate the imput.
 

veggieman

Veteran Member
Joined
Jan 1, 2008
Location
Sweet Home Alabama!
TDI
04 Golf
Okay, I don't have my Bentley manual with me, but going off this picture, (01 Jetta):


Mine is a 98 BTW.
I disconnected the wire to the only sensor on the hard, black twin air pipe to/from the intercooler. Did I disconnect the correct plug? I have a feeling I did not!!

Anyway, 58 degrees and the Jetta has been sitting for 7 hours. I disconnected the wire, let the car sit for about 30 seconds then turned the key on. Glow plug light came on then went off immediately and the Jetta fired right up. With it being nearly 60 degrees, I think it would have done that anyway!

If someone can point me to the correct location of the plug I'm looking for, I'll try it again in the monring. I'll can also look in the Bentley manual later tonight.

Thanks,
~Jason
 
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veggieman

Veteran Member
Joined
Jan 1, 2008
Location
Sweet Home Alabama!
TDI
04 Golf
Even on a A3? I'll do it in the morning.

Now my check engine light is on for the 1st time since I've owned it. Would that have to do with the plug I disconnected earlier?

This is one of those rare model that runs so well, gets awesome MPG and does everything right. Now this little upset has me very annoyed!!!:mad:
 

whitedog

Veteran Member
Joined
Jul 12, 2004
Location
Bend, Oregon
TDI
2004 Jetta that I fill by myself
veggieman said:
Even on a A3? I'll do it in the morning.
My Bad. I don't know the A3s at all and since I didn't read, I was thinking that was a picture of an A3.

In other words: I don't know for sure of anything here.
 

veggieman

Veteran Member
Joined
Jan 1, 2008
Location
Sweet Home Alabama!
TDI
04 Golf
I found the sensor, disconnected it and turned the key on. The glow plug light stayed on for about 20 seconds, went off and the Jetta popped right off.

I'll grab a new temperature sensor.

Now...what about the check engine light? Can I reset it somehow by disconnecting the battery?
 

rdkern

Top Post Dawg
Joined
May 21, 2004
Location
Humboldt Co CA
TDI
Passat 1997 silver (sold after 11 years), Jetta 2000 atlantic blue
The gps staying on is masking your real problem. They shouldn't stay on with the temps at 40 +. Fix the timing. The temp sensor has not been shown to be at fault.

Get a vag com on it to see the code and clear it if needed. You should have a gp code do to unplugging the temp sensor.

Fix the timing.
 

2000_tdi

Member
Joined
Mar 23, 2008
Location
Georgia
TDI
2000 1.9 tdi jetta
where did you get the temp sensor and for how much? I have the same problem on my 2000!!!!
 

bigbillyboy

Member
Joined
May 3, 2008
Location
NW
TDI
none
what!?!?! I'm confused

I thought I had found something, but now it doesn't seem like it. my 2000 NB has the GP light come on only for about a half a second, cold or hot. In the morning (cold) It needs to crank for about 5 seconds. When warm, it fires right up. I followed ALL of the guidelines in the glow plug section. One bad plug, replaced all four. Still GP light comes on for only 1/2 a second, cold or hot, and it has to crank a bit when cold. Checked all the wires, fuses, and relays. All good. Getting 12.8V to all plugs, and all wires.

Through all of this the CEL light comes on about 30 seconds after startup, and the only code is the 380 Engine Heat Circut fault. If I unplug the coolant sensor, the GP's stay on for about 20 seconds, and it fires right up, cold or hot, but I still get the CEL light for Engine heat circuit.

I don't have a gauge, as the NB only has the light. The coolant light seems to work correctly, as it is blue at startup, and then shuts off.

Two questions,
If I don't have the code reset by a VAG COM, will I still get the quick light on the GP's?

Can the coolant sensor go bad, so that the GP's don't function properly, but not get a code for the coolant sensor?

this is driving me nuts, and I can't get it through Emissions testing until the CEL light is out.

PLEASE HELP
 

Lug_Nut

TDIClub Enthusiast, Pre-Forum Veteran Member
Joined
Jun 20, 1998
Location
Sterling, Massachusetts. USA
TDI
idi: 1988 Bolens DGT1700H, the other oil burner: 1967 Saab Sonett II two stroke
I'll be looking for this thread to be moved to the A3/B4 model specific forum and will reply once it's asked there.
 

weedeater

Top Post Dawg
Joined
Mar 17, 2001
Location
Reston, VA
TDI
Jetta, 2001, Baltic Green
Two questions,
If I don't have the code reset by a VAG COM, will I still get the quick light on the GP's?
Yes.

Can the coolant sensor go bad, so that the GP's don't function properly, but not get a code for the coolant sensor?
yes.

You have an A4. IIRC, there is a way via vagcom to extend the gp interval. Basically fool it into thinking it is colder than it is.
 

smokyTDI

Active member
Joined
Jun 11, 2008
Location
Ottawa, Ontario
TDI
2001 VW Golf
ahhh, i'm having the same problem exactly.... Veggieman, was your timing adjusted, or did the problem went away 'by itself'?
i replaced the coolant temp sensor, no help.
 

newbug

Member
Joined
May 27, 2009
Location
Jersey City, NJ
TDI
1984 Jetta, 1999 Beetle, 2002 Jetta, 2005 Passat Wagon
Glow Plug lights for a second car won't start.

I just had a major problem with my car not starting.
It started about a week ago took several attempts but it started ran rough til it warmed up plus smoked a lot.
113,000 miles on 2002 VW Jetta TDI.
The last 2 days (April 18, 19, 2018) very hard starting and yesterday wouldn't start at night no matter what I tried. Killed the battery too.
So I charged it up and tried again finally got it to start after turning the key on and off maybe 20 times to get the glow plugs hot. Started and ran but 1 hour later no good.
So today (April 20, 2018) I changed the 109 relay as I always have a spare after breaking down in my 1999 Bug.
No good same thing.
Put the Vac Com on it no codes except for door and windows from the battery going dead while trying to start.
I also removed the plug from the temp sensor under the vacuum pump and when turning on the key the Glow Plug light stayed on for about 10 seconds but the car would not start even after 4 attempts, so I put the plug back on another strike out.
Called Ross-Tech and after telling them all I did no solution was found.
So I as a last resort removed all the Glow Plugs.
I tested them with a Fluke Ohm meter and they all had less than 1 ohm resistance. I then tested my brand new Bosch spares and same thing.
So the next thing I did was use my 20 amp variable supply and tested each Glow Plug raising the voltage from zero to 13 volts and checking the amps they used.
The amps were 6 and lowered to 4.5 after the Glow Plug turned red.
The last Glow Plug Read zero volts and zero amps.
So I rechecked the other one and the new ones and all were about the same.
I rechecked the one that read Zero and same thing which meant it was shorted under voltage and I believe was killing the voltage and current to the entire 4 Glow Plugs. Funny but no Codes?
So I put in 4 new Bosch Glow Plugs and the light came on and off but the car started right away I tried several times later after the coolant temp dropped and it started again so as of now all looks good.
Strange thing also I was checking the TDI timing and even with a 193 degree on gauge and 85.9 Celsius said engine not warm enough 80c should have been enough maybe the shorted Glow Plug was screwing up the ECU.
I will check it later but now it starts as soon as you turn the key no cranking.
Hope this helps.

Today 4-21-2018 and last night 4-20-2018 the car started right up maybe 1 turn of motor several times at about 35 degrees no more problems.
Looks like all is solved.
 
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Ol'Rattler

Top Post Dawg
Joined
Jul 3, 2007
Location
PNA
TDI
2006 BRM Jetta
I found the sensor, disconnected it and turned the key on. The glow plug light stayed on for about 20 seconds, went off and the Jetta popped right off.
I'll grab a new temperature sensor.
Now...what about the check engine light? Can I reset it somehow by disconnecting the battery?
There is your smoking gun for the CTS. If unplugged the ECU thinks the coolant is something like Minus 40F.

The temp sensor's accuracy drifts when they get old and they are pretty cheap to replace. I would go to the dealers to avoid getting a Chinese garbage sensor. Don't forget to get the O-ring while you are there.

For the code get a free scan at an auto parts store. They will give you a print out of what codes are stored and they will clear them for you if you want them to. There is a good chance the code is "CTS implausible signal" or "CTS out of range" meaning the ECU is calling BS on the CTS signal.

If you clear any codes or disconnect the battery, even if the CIL does not come back on, you will need to drive the car for a few days before you go in for emissions. That will reset something called "readiness" in the ECU.

Putting the timing back to spec as mentioned earlier is sage advice, as well. How old is your timing belt? It might be due for replacement. If it fails, because TDI's are "interference" engines, your head will need to be removed to repair the valve to piston damage that would result.
 
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BobnOH

not-a-mechanic
Joined
May 29, 2004
Location
central Ohio
TDI
New Beetle 2003 manual
I believe the fix was the act of plugging and unplugging the harness, re-established contact.
 
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