Glow plug light flashing

Boxer246

Member
Joined
Feb 18, 2008
Location
Houston, TX
TDI
AHU going into Vanagon
Just got my head back on the '98 AHU after timing belt failure and subsequent head rebuild. Finally got the car started after hours of trying to figure out why injection pump wouldn't prime...(main wiring connector to injection pump was loose, not clipped in DUH!!). Anyway, now after about 30 seconds of engine running, the glow plug light begins flashing.
Any idea what this might mean?
I did replace the glow plug harness because the old one had desintegrated. I did not splice the wires to the old harness, like some do, rather I was able to remove the spade connectors from the main round harness disconnect and plug the new spade connectors in like original.

I dont have a VAG-COM yet so I cant diagnose that way.
 

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 are the brake lights working? Bad bulbs or switch are normal cause of this.
 

Seatman

Top Post Dawg
Joined
Apr 23, 2010
Location
Scotland
TDI
2014 Skoda rapid elegance 1.6 cr tdi
Does the throttle still work when the lights flashing? I had my light flashing when the tps stopped working.
 

Boxer246

Member
Joined
Feb 18, 2008
Location
Houston, TX
TDI
AHU going into Vanagon
Ah, I just read a thread on this. Yes it seems like bad brake light bulbs or brake light switch can cause the glow plug light to flash. Its pissing rain right now, will have to wait till tomorrow to investigate further.

Seatman....throttle seems to work fine but I haven't taken the car for an extended shakedown yet. Just took it around the block after I got it all buttoned up tonight.
 

rdkern

Top Post Dawg
Joined
May 21, 2004
Location
Humboldt Co CA
TDI
Passat 1997 silver (sold after 11 years), Jetta 2000 atlantic blue
Does the throttle still work when the lights flashing? I had my light flashing when the tps stopped working.
Sometimes the TPS works, sometimes it doesn't. My wife's A4 still ran fine, just no cruise when the switch was going out. Don't understand why, since I would think it should have overridden the TPS, but in her case it didn't seem to affect that part of the drivability. It's nice when the car gets her home, so I didn't concern myself too much with this question at the time.
 

Seatman

Top Post Dawg
Joined
Apr 23, 2010
Location
Scotland
TDI
2014 Skoda rapid elegance 1.6 cr tdi
It turned out my ecu was soaked through but luckily after I took it apart, cleaned some crud off the board, resealed it and put it back on the car everything was fine and has been since. The brake lights and switch are new to me, I'll have to keep that in mind for the future.
 

Boxer246

Member
Joined
Feb 18, 2008
Location
Houston, TX
TDI
AHU going into Vanagon
Well drove the car about 100 miles today, glow plug light flashing the whole time. Brake lights (all three) are working fine, throttle seems to work fine.

Disconnected 3rd injector harness, reconnected, no change.
Guess I'll have to wait till I can hook it up to VAG Com.
 

Seatman

Top Post Dawg
Joined
Apr 23, 2010
Location
Scotland
TDI
2014 Skoda rapid elegance 1.6 cr tdi
Did you check the switch on the brake pedal? My car has 2 for some reason.


 

lowpolo

Active member
Joined
Sep 28, 2009
Location
leeds
TDI
corrado ahu, mk5 polo tdi
the black switch is for the brakes and the blue one for the cruise control switch off
 

vgmnstr

Veteran Member
Joined
May 13, 2006
Location
Lake Worth, FL (33467)
TDI
2001 New Bettle TDI
Mine came on today too. I know a faulty brake light switch will cause it. I had that replaced two years ago with the recall. Will an open rear bulb really set it off?
 

vgmnstr

Veteran Member
Joined
May 13, 2006
Location
Lake Worth, FL (33467)
TDI
2001 New Bettle TDI
Mine came on today too. I know a faulty brake light switch will cause it. I had that replaced two years ago with the recall. Will an open rear bulb really set it off?

And now after going to check, i only have a third brake light operational. Checked the wiring diagram, 3rd brake works, tail lights work, turn signals work. I'm thinking the brake light switch.

Anyone happen to know what VW's parts warranty is? I think I had it replaced just under 2 years ago under the recall.
 

tstdimk4

Veteran Member
Joined
Jun 10, 2009
Location
windsor, ON
TDI
2001 Jetta TDI
where is the brake light switch exactly? my glow plug light started to flash today and my cruise wont work either.. so im guessing its this switch thats causing the problem. and i just went out and checked the lights, only the third brake light comes on.. the left and right are out
 

vgmnstr

Veteran Member
Joined
May 13, 2006
Location
Lake Worth, FL (33467)
TDI
2001 New Bettle TDI
where is the brake light switch exactly? my glow plug light started to flash today and my cruise wont work either.. so im guessing its this switch thats causing the problem. and i just went out and checked the lights, only the third brake light comes on.. the left and right are out

First thing I went after was the bulbs. I don't know if anyone else has this problem, but my right side brake lamp bulb is always going out. Checked it, and the filament was in tact.
 

vgmnstr

Veteran Member
Joined
May 13, 2006
Location
Lake Worth, FL (33467)
TDI
2001 New Bettle TDI
They may have looked in tact, but were not. The bulbs I swapped in (out of an open package in my glove box) turned out to be bad as well. I guess the light can flash when both brake lights fail.




First thing I went after was the bulbs. I don't know if anyone else has this problem, but my right side brake lamp bulb is always going out. Checked it, and the filament was in tact.
 
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