No codes found for blinking glow plug light

miltoncf

Spammer
Joined
Jan 14, 2009
Location
arizona
TDI
ALH jetta wagon
Hello,
Autozone used a cheap OBD2 scanner that had to plugged into a PC after doing the scan, and O'Reilly used a stand-alone Bosch scanner. Neither one found a code. However Autozone noticed that my R+L brake lights were out, with the centre one still working. As my 2003 TDI had the brake light switch recall work done in 2007, should I be having this problem? In other words, did the dealer put in a switch identical to the one that was to be replaced? They did just that when replacing a faulty temperature sensor that went out at 40k, only to have it go bad again at 80k, and even after replacing it again, it lit up the red temp. light like clockwork at 120k, yet it did disappear after something else was fixed. I suppose a real VAG scanner should be used, but should the light be flashing when the brake lights are out with the new & improved brake light switch?
 

STDOUBT

Veteran Member
Joined
Jul 30, 2007
Location
Portland, effing Oregon
TDI
dos jettas
I'm sorry I didn't save the name of the tdiclub member that posted this, but I saved it for a reference. Here ya go:

Causes of a flashing glow plug light
Because this is a frequently asked question, I went digging through info for '01 ALH and made the followin
g list of known reasons for the glow plug light to flash. They are listed with the VW code and generic rea
der P code.

00741 Brake pedal monitoring - implausible signal
01044 Control unit incorrectly coded
16705/P0321 Engine speed sensor - implausible signal
16706/P0322 Engine speed sensor - no signal
16955/P0571 Brake light switch (F) - implausible signal
17653/P1245 Needle lift sender (G80) - short to earth
17654/P1246 Needle lift sender (G80) - Implausible signal
17655/P1247 Needle lift sender (G80) - Open circuit/short to positive
17762/P1354 Modulating piston movement sender (G149) - electrical fault in current circuit
17969/P1561 Metering adjuster (N146) - control difference
17978/P1570 Engine control unit blocked
18020/P1612 Control unit incorrectly coded
18026/P1618 Glow plug relay (J52) - short to positive
18027/P1619 Glow plug relay (J52) - open circuit/short to earth
18040/P1632 Accelerator position sender - voltage supply

It also flashes when an interface tool has put the ECM in 'basic settings' mode.

There may be more; these are the ones I found documented.
 

JETaah

Vendor , w/Business number
Joined
Jan 18, 2001
Location
mi 48836
TDI
96 B4V, 1999.5 jettaIV,2005 BEW Beetle
Did you check the bulbs and fuses for the brake lights?
A failure in that system will cause a flashing glow plug light.
 

AndyBees

Top Post Dawg
Joined
May 27, 2003
Location
Southeast Kentucky
TDI
Silver 2003 Jetta TDI, Silver 2000 Jetta TDI (sold), '84 Vanagon with '02 ALH engine
The two brake light bulbs being out is the cause of the flashing GP light. (should be on the list)

The ECU monitors the left and right brake lights but not the top center light. When both go out is the prompt for the ECU to send the cue for the GP light to flash.

MoGolf originally put that list together. I expanded it a bit and from time to time posted it. I don't have it on this laptop.
 

JB05

Top Post Dawg
Joined
Oct 20, 2005
Location
Il.USA
TDI
Golf,2005,anthracite blue
Yep, MOGolf is the OP to the above mentioned thread. He has other informative threads; as well.
 

BobnOH

not-a-mechanic
Joined
May 29, 2004
Location
central Ohio
TDI
New Beetle 2003 manual
Believe that list was for CEL accompanied by flashing GP.
May not be a code for bulbs. I do know the bulbs/sockets can be finicky
 

miltoncf

Spammer
Joined
Jan 14, 2009
Location
arizona
TDI
ALH jetta wagon
Thanks for the replies. As it's unlikely that the two light blew at the same time or are wired in series, I'll check the fuse.
 

BobnOH

not-a-mechanic
Joined
May 29, 2004
Location
central Ohio
TDI
New Beetle 2003 manual
Also check the bulb sockets, clean and carefully bend the bottom tang up just a tad.
 

AndyBees

Top Post Dawg
Joined
May 27, 2003
Location
Southeast Kentucky
TDI
Silver 2003 Jetta TDI, Silver 2000 Jetta TDI (sold), '84 Vanagon with '02 ALH engine
If only one bulb is blown, the GP will not flash. If both are blown the GP will flash, and if I remember correctly, there will not be a CEL.

I have a "dummy" single bulb set-up under the back seat of my 84 Vanagon with the ALH for the ECU to monitor. It is happy and there's no flashing GP light (Yep, I installed the Jetta cluster..)

If there is no current going through the bulb filament, the GP will flash. Also, LEDs and the ECU do not get along. Seems someone posted how to use a resister to fool the ECU. Not sure how that works or would inform you if the LED brake light quit working
 

Tdijarhead

Top Post Dawg
Joined
Nov 10, 2013
Location
Lawrenceville PA
TDI
2003 TDI Jetta Daughters Car, 2001 TDI Beetle, Wife’s car, 2005 Golf TDI Mine, all 5 spds
I like to keep a couple of extra bulbs around I’m afraid I’d have replaced the bulbs and checked the sockets already on both sides.

They didn’t fail together one died about a 2 months ago and the other went out a week or so ago and it’s just been noticed.
 

oilhammer

Certified Volkswagen Nut & Vendor
Joined
Dec 11, 2001
Location
outside St Louis, MO
TDI
There are just too many to list....
I had BOTH the headlight bulbs on my Mazda pickup blow suddenly at the same time.... saw it happen, I know for sure, because the truck was in the driveway up against the closed garage door, wife was with me. 5am, 3 degrees, dark winter morning.

So never assume both bulbs cannot go at once. However, it is FAR more likely I agree that one has been bad for a while and finally the other went. While we do have biannual inspections here, we at the shop always check lights on every car we pull in here, no matter what it is here for. And there is NEVER a day that goes by that we don't find a vehicle with a bulb out somewhere. Good habit to try and check them periodically.
 

miltoncf

Spammer
Joined
Jan 14, 2009
Location
arizona
TDI
ALH jetta wagon
Thanks for the replies. As it's unlikely that the two light blew at the same time or are wired in series, I'll check the fuse.
Fuse 13 looked good, but just to be sure I swapped it with 14 which is also for lights. Then after replacing just the right side, both brake lights now work, so it seems that they ARE in series.

The previous owner of my 2003 wagon apparently had something installed on the left side, as there's a hard styrofoam rack that looks difficult to remove, as I could only see two of the mounting screws. Fortunately, the blown bulb causing the glow plug blink was on the right side. Yet right below that socket was a blown rear fog light bulb, which is rather interesting, as it didn't come with the fog light option, so it never should have been used, esp. as it's not even possible to pull the light switch to turn the fog lights on.
 

AndyBees

Top Post Dawg
Joined
May 27, 2003
Location
Southeast Kentucky
TDI
Silver 2003 Jetta TDI, Silver 2000 Jetta TDI (sold), '84 Vanagon with '02 ALH engine
According to the electrical schematics, the brake lights are not in series. They are parallel. The OP may have made changes to install an electrical pig tail for a trailer or adding the fog lights.
 

Geordi

Veteran Member
Joined
Jan 4, 2002
Location
Somewhere between Heaven and Hell. But it is reall
TDI
14 JSW DSG, 03 Wagon 01M, 400k and IPT performance auto!
Here's a challenge for the wiring geniuses around...

My 03 ALH wagon has the outer single elements lit on the top brake light - but only when the parking lights or headlights are on. They behave normal with the use of the brake pedal.

I also (now) have this stupid blinking glow plug light, but ALL brake lights seem to be working just fine? The top two are lit with the parking lights, and the top element is the only one that lights bright with the brakes - and they are functioning. Philips LEDs.

So what's going on? Previously the top light elements (but only the end ones) would flash when unlocking the car or locking... But that doesn't happen anymore. Stupid computer controlled lights.
 

Howie09tdi

Active member
Joined
Sep 19, 2017
Location
New York
TDI
2009 Jetta TDI(buyback gone) 2015 BEETLE TDI
Can someone explain why my 2015 Beetle TDI goes into "limp mode" under hard acceleration? The glow plug light flashes, no codes found and cycling ignition clears it then car drives normally no power loss has happened 2x
 

AndyBees

Top Post Dawg
Joined
May 27, 2003
Location
Southeast Kentucky
TDI
Silver 2003 Jetta TDI, Silver 2000 Jetta TDI (sold), '84 Vanagon with '02 ALH engine
If only one bulb is blown, the GP will not flash. If both are blown the GP will flash, and if I remember correctly, there will not be a CEL.

I have a "dummy" single bulb set-up under the back seat of my 84 Vanagon with the ALH for the ECU to monitor. It is happy and there's no flashing GP light (Yep, I installed the Jetta cluster..)

If there is no current going through the bulb filament, the GP will flash. Also, LEDs and the ECU do not get along. Seems someone posted how to use a resister to fool the ECU. Not sure how that works or would inform you if the LED brake light quit working

Ah, but Geordi, you never read all the posts in this short Thread ....

Here's a challenge for the wiring geniuses around...

I also (now) have this "stupid" :D blinking glow plug light, but ALL brake lights seem to be working just fine? The top two are lit with the parking lights, and the top element is the only one that lights bright with the brakes - and they are functioning. Philips LEDs. <<<< There's your problem.

So what's going on? Previously the top light elements (but only the end ones) would flash when unlocking the car or locking... But that doesn't happen anymore. Stupid computer controlled lights.
 

Matt-98AHU

Loose Nut Behind the Wheel Vendor
Joined
Apr 23, 2006
Location
Gresham, OR
TDI
2001 Golf TDI, 2005 Passat wagon, 2004 Touareg V10.
According to the electrical schematics, the brake lights are not in series. They are parallel. The OP may have made changes to install an electrical pig tail for a trailer or adding the fog lights.
Correct, they are not in series, I believe the computer is looking for a specific voltage drop on that circuit, and if the load isn't high enough due to both bulbs being burned out, it will set the brake switch implausible signal code. It's a single wire out from the brake switch, but somewhere the signal/load wire to the ECU is spliced in, and later the wire is split off to go to each individual brake light in the rear.

I have a car at my shop now with LED bulbs that caused the code to come on. You can get "load resistors" from a local auto parts store that simulate the load a bulb puts on the circuit and it makes the computer happy. Wire one side to the power in for the brake bulb (vampire clips provided) and one wire to the ground, and it creates a high enough load that it fools the computer into thinking everything is hunky dory.
 

miltoncf

Spammer
Joined
Jan 14, 2009
Location
arizona
TDI
ALH jetta wagon
According to the electrical schematics, the brake lights are not in series. They are parallel. The OP may have made changes to install an electrical pig tail for a trailer or adding the fog lights.
As posted below, somebody had added fog lights as it couldn't have been supplied with blown fog light bulbs from the factory, and the prior owner left the towing hitch on, which I had to have removed.

http://forums.tdiclub.com/showthread.php?p=5418652#post5418652
 
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