Glow plug indicator light code...but everything works!!!

mannytranny

mannytranny

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CA
TDI
02 Jetta (sold, such a great car) '16 Touareg
So I've been ironing out all of the little issues with my Sidekick TDI (AHU). She runs GREAT (so much smoother than my MTDI Sidekick) But there are a few issues...

I consistently get a MIL code for faulty glow plug indicator lamp. (Open/Short to ground) I've wired it properly and it works properly, but always throws this dang code! I measured 30 Ohms of resistance across the lamp I'm using, shouldn't that be enough? Otherwise, I can't quite figure out why it claims short to ground since the ECU is the ground.

Has anyone run across this before? Any work around?

TIA!
 
K1Cowboy

K1Cowboy

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2000 Audi S4 AFN TDI
I measured the glow plug light on a TDI cluster i had laying around. It measures 13.2 ohms. You have almost 3x that. That might be why it thinks it's a short to ground. Your bulb might be too big. Also, the distance and thickness of the wire running to the bulb can affect the resistance value, same for any crimps or connections in the harness to the light.
 
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jimbote

jimbote

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spiral arm, milky way (aka central NC)
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K1Cowboy said:
I measured the glow plug light on a TDI cluster i had laying around. It measures 13.2 ohms. You have almost 3x that. That might be why it thinks it's a short to ground. Your bulb might be too big. Also, the distance and thickness of the wire running to the bulb can affect the resistance value, same for any crimps or connections in the harness to the light.
Click to expand...
this^^ try reducing your bulb size to around 1watt ;)
 
mannytranny

mannytranny

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02 Jetta (sold, such a great car) '16 Touareg
Oh, I see what you mean...makes sense. Hard to believe these things are that touchy on the bulb size. eeek

;)
 
mannytranny

mannytranny

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02 Jetta (sold, such a great car) '16 Touareg
Well I went to the store and bought two other bulbs...

One is a 1.2 watt that shows 17 Ohms of resistance and the other is a .3 watt that does not show any resistance.

Both lights work as they should, but both lights also produce the error code. Argh
 
Vince Waldon

Vince Waldon

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2001 ALH Jetta, 2003 ALH Wagon, 2005 BEW Wagon
EDIT... my fingers are a bit slow

Would you be able to post the actual code you're getting... and what scanner you're using?

You're resetting the code each time, right?

I'm surprised you're having this much trouble with the lamp... and also a little bit surprised that it's actually monitored.

Having said that, on a normal dash it's a yellow LED, so maybe the issue is you're using something that doesn't have a 1.7V drop... or about 20mA of current... or something else related to using a bulb rather than an LED.

Still strikes me as strange that the ECU pays attention to the indicator LED... but those engineers had minds of their own. :):)
 
jimbote

jimbote

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spiral arm, milky way (aka central NC)
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Vince Waldon said:
EDIT... my fingers are a bit slow

Would you be able to post the actual code you're getting... and what scanner you're using?

You're resetting the code each time, right?

I'm surprised you're having this much trouble with the lamp... and also a little bit surprised that it's actually monitored.

Having said that, on a normal dash it's a yellow LED, so maybe the issue is you're using something that doesn't have a 1.7V drop... or about 20mA of current... or something else related to using a bulb rather than an LED.

Still strikes me as strange that the ECU pays attention to the indicator LED... but those engineers had minds of their own. :):)
Click to expand...
b4 passats used an LED but mk3 used an incandescent, still this is a puzzling code ...
 
mannytranny

mannytranny

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Location
CA
TDI
02 Jetta (sold, such a great car) '16 Touareg
I'm using Vagcom and the code says 'Glow plug indicator - K29 - Open or short to ground' I reset it every time and it comes back without fail when turning on the ignition. Clear code, try new lamp, clear code, new lamp, etc. I've tried three lamps now with varying resistance.

In searching, I found that there may or may not be differences with ECU's and wiring...but nothing was really conclusive.

Nothing is easy, eh?!
 
mannytranny

mannytranny

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Location
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TDI
02 Jetta (sold, such a great car) '16 Touareg
I think I'll try a LED and see if thats better.
 
Vince Waldon

Vince Waldon

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Joined
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Location
Edmonton AB Canada
TDI
2001 ALH Jetta, 2003 ALH Wagon, 2005 BEW Wagon
The format of the code you're getting is not something I'm familiar with unfortunately... generally the codes are formatted PXXXX or PXXXXX in my experience.

Having said that, googling for "Glow plug indicator K29" reveals a bunch of threads on this site that seem to point to a cluster communication issue perhaps.
 
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mannytranny

mannytranny

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02 Jetta (sold, such a great car) '16 Touareg
Oh, I'll remember to look at the p code next time.

Thanks!
 
jimbote

jimbote

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how long is your wire from ecm to bulb ? is it still the oem wire or did you add wire?
... try wiring the other end of the bulb (12v) directly to battery and see if anything changes
 
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mannytranny

mannytranny

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02 Jetta (sold, such a great car) '16 Touareg
I'd say the length is about 4 ft. I didn't make this harness, Fast Forward Auto did, so I'm not sure what happened. He mentioned that the harness had some corrosion in it and he had to ditch some of the original wire and add new. He did a very good job otherwise, so I'd imagine he used the appropriate gauge, etc.

I'll run a wire to the battery and see what happens. Could also check the resistance in the wire from the ECU, right?

Thanks for the help!
 
jimbote

jimbote

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spiral arm, milky way (aka central NC)
TDI
Tacoma 4x4 converted to TDI
mannytranny said:
I'd say the length is about 4 ft. I didn't make this harness, Fast Forward Auto did, so I'm not sure what happened. He mentioned that the harness had some corrosion in it and he had to ditch some of the original wire and add new. He did a very good job otherwise, so I'd imagine he used the appropriate gauge, etc.

I'll run a wire to the battery and see what happens. Could also check the resistance in the wire from the ECU, right?

Thanks for the help!
Click to expand...
yes check resistance .... it could be as simple as a corroded wire to the ecm... good luck !
 
mannytranny

mannytranny

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Joined
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Location
CA
TDI
02 Jetta (sold, such a great car) '16 Touareg
I see .6 Ohms of resistance in the wire between the ECU and bulb.
 
mannytranny

mannytranny

Top Post Dawg
Joined
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Location
CA
TDI
02 Jetta (sold, such a great car) '16 Touareg
Winner, Winner. Once wired directly to the battery for the +12v lead, the code did not appear. I had it wired to +12v when the ignition is on. Apparently the ECU didn't care for that. Glad to have it all buttoned up! Thanks a TON for the help, fellas!

I still occasionally get codes that show up for DF alternator load signal and Vehicle Speed Sensor, but I'm hoping that those won't cause a CEL. (haha)

Thanks again, I've got to put up some pics of this tractor!
 
jimbote

jimbote

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spiral arm, milky way (aka central NC)
TDI
Tacoma 4x4 converted to TDI
mannytranny said:
Winner, Winner. Once wired directly to the battery for the +12v lead, the code did not appear. I had it wired to +12v when the ignition is on. Apparently the ECU didn't care for that. Glad to have it all buttoned up! Thanks a TON for the help, fellas!

I still occasionally get codes that show up for DF alternator load signal and Vehicle Speed Sensor, but I'm hoping that those won't cause a CEL. (haha)

Thanks again, I've got to put up some pics of this tractor!
Click to expand...
nice!! :).... if you have it wired to just ignition on and not start also, the ecm could detect a fault in that short interval between key "on" and actual time it takes for the truck to start and then back to key on... pics and videos please! :)
 
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