Major Glow Plug #*!&@^$

Car Info: 2003 Jetta GL W/ 5 Sp transmission
I hope someone can answer this glow-plug related question:

The owner came to me with a starting problem.
The primary complaint is difficault starting.

Once the engine is started the everything is OK.
Here is the info I can provide:
1. There are no DTC's
2. The timing is near the center line on the timing graph
3. GP resistence are all less than 2 Ohm (within 0.4 Ohms)
4. Static timing is dead on (crank, cam & pump pinned)

*Befor the owner came to me he has installed a new starter.
* Battery holds a full charge and the grounds are clean

Here is where things get interesting:
Once the engine does start it will issue a plume of white smoke and idle rough for about 4-5 seconds then run smoothly. Performance is very good. The "Stealership" replaced the injection pump ( 8 months ago)and the problem persists.


Today the intake manifold was removed and cleaned (cylinder head ports cleaned too).

The engine will crank 20-25 seconds then finally the engine will start and sputter to life.

I replaced the engine temp censor (ETC) still the starting problem persists.

Then I disconnected the ETC electrical connection and let the glow plug perform the full 20 second duty cycle. The engine starts PERFECTLY!
This test resulted in only one DTC (ETC open /short to ground related).

I then went to check the GP relay and this is where this tale of woe gets really interesting.

ETKA lists this relay (marked #180) for position 10 on the relay panel.
When I went to check the relay panel there was no relay in position #10 but neither is there a relay socket for the relay to be inserted.

There is an open hole ...no wires, no leads and no relay socket! *** ????

Someone out there has to have an answer for this one...please let me know.

TIA
Herm

maybe bad tank of fuel?

Herm TDI said:

Then I disconnected the ETC electrical connection and let the glow plug perform the full 20 second duty cycle. The engine starts PERFECTLY!

Click to expand...

Herm, most people including yourself know a whole lot more than me. But I'll tell you what comes to my mind.

A couple months ago I went to my local discount foreign auto parts store to get a spare glow plug for my 04 TDI. They had Beru, so I took it.

I got home and just on a whim I pulled a plug from my TDI to compare the two plugs and immediately noticed that they were different.

My OEM plug had a little tit on the end. So I hooked up plug to the battery to observe the heatup. No delay, instant on, bright red glow.

I hooked up the Beru plug with no tit on the end and it took a good 8-10 seconds to glow red. Just like in my 86 jetta TD and 82 Datsun diesel.

I took it back and then went to my local VW dealer and they tried to sell me a Bosch that looked just the same and they insisted that it was the correct plug.

I insisted that it was the wrong one and so they did some more checking and finally admitted it was the wrong plug for my TDI and they did not stock them.

Now, in the car your working on, I'm wondering if perhaps the incorrect glow plugs were replaced somewhere along the way resulting in inadequit preheat.

I'm most likely wrong but I thought I'd put in my 2¢. Hope it helps though.

I thought 2002 and newer Tdi's had a solid-state GP relay rather than a mechanical one...don't know the location, but I imagine it wouldn't even fit in the spot mentioned. Could ETKA be wrong in this case?

HermTdi said:

I replaced the engine temp censor (ETC) still the starting problem persists.

Then I disconnected the ETC electrical connection and let the glow plug perform the full 20 second duty cycle. The engine starts PERFECTLY!
This test resulted in only one DTC (ETC open /short to ground related).

Click to expand...

You're talking about the engine coolant sensor, underneath the coolant auxillary glow heaters, pointing back toward the firewall, right?

Sounds like a bad connection/short in the temp sensor wiring somewhere...hmmmm...really you know a lot more about these cars than most of us.

Also, did you check for air bubbles/air leak leading to the IP?

" ETKA lists this relay (marked #180) for position 10 on the relay panel.
When I went to check the relay panel there was no relay in position #10 but neither is there a relay socket for the relay to be inserted."

Any chance the relay panel was replaced or the wrong one installed at the factory?

Also, the glow plugs changed (different part number and voltage rating, although they look the same) for the BEW engine (2004 and 2005). If you are working on a 2003, it should be an ALH engine. Perhaps the relay changed too. Maybe something else to verify that the right parts are installed for the 2003. If it was a late 2003, say July 2003, perhaps the wrong parts were installed at the factory.

--Nate

nicklockard said:

I thought 2002 and newer Tdi's had a solid-state GP relay rather than a mechanical one...don't know the location, but I imagine it wouldn't even fit in the spot mentioned. Could ETKA be wrong in this case?

Click to expand...

This is correct. Bentley claims that the only way to check the function of the "glow period control module (J370)" is to use a current pick-up clamp on the glow plug wiring within 3 minutes of starting a cold car. Not sure where this creature lives, but my money would say it is hidden at the top of the wire loom where the glow plug harness connects to the loom. Take a look at wiring diagram 65/3 in Bentley, that seems to support my theory.

Verify the condition of the glow plugs by removing them and using a battery jumper cable test them in air. See if they they all glow and if they glow fast. I suppose it's possible to have a failure where one ohms out ok cold but then goes open circuit on warm up?

jmur said:

Verify the condition of the glow plugs by removing them and using a battery jumper cable test them in air. See if they they all glow and if they glow fast. I suppose it's possible to have a failure where one ohms out ok cold but then goes open circuit on warm up?

Click to expand...

Hello Jeff,
I'll have the car back tomorrow.
This is another test I want to do.

Thanks

Is this strictly a cold start issue? If it isnt, then I wouldnt expect it to be glowplug related.

I'd bump the timing to half way between centerline and top acceptable. A compression test should be done.

From Sep 01 production the GP relay is supposed to be in the plenum with the ECM (per Bentley wiring diagram). I've not had a need to go looking for one. Wherever you locate it, it should have part number 038 907 281 A.

It's possible (although unlikely) that the glow filament in all four plugs has failed short-to-earth and that the only heating is in the control filament. An ammeter check would show higher than normal consumption, a test of the plug on the bench would reveal the plug beginning to glow halfway up, rather than at the tip...

Sound like my problem

I have a 2004 Jetta PD TDI . I have trouble starting it when it is cold. This morning I had to crank the car until the oil light comes back on for it to start and it was around 40F. I have been to the stealership 3 times.
1. did the TSB injector, plugs, and computer change.
2. tested the plugs and said evrything was ok (no clue how they tested the plugs).
3. cleaned the intake, and said that it was fixed.

I plan on sending the car back to the stealership next week. what could I tell them to help them diagnose the problem?

Could the engine timing be retarded too much?
Could the glow plug relay be bad?
What is left that the TSB did not cover?
????

Herm, Volkswagen's relay block diagrams are notoriously "generic", with relay positions moved about depending on what equipment the car has, what plant it was built at, etc. I always try and look for the "control number" on the relay, usually in big contrasting numbers (like relay 109, for instance).

There are several control numbers for the glowplug relay. But the later units such as the 2003 in question work a little differently and I admit I have not had much experience troubleshooting them as I have not run across any problems with them.

From your test it sure sounded like the ECT sensor was flakey. Be sure they sold you the correct one, there is a VAG part number right on them. I'd also as MOGolf suggested get the timing at the top of the graph, and since the dealer installed a pump I'd make sure the belt timing is correct and the tensioner is set correctly

You may have a bad glowplug control unit, though. With the ECT sensor unplugged, the ECU will command full glow and override the control unit's logic for glow duration as well as afterglow. So unplugging the sensor may make you think it is bad, when in fact the glowplug control unit (relay) is bad.

I believe VAG-COM has an active test for the glowplug control unit, you could listen for it clicking to find it.

found this on dieselgeek's web site
this might help

Late" Bosch Glow Plug Relay for TDI. 038 907 281C

this relay fits:
Golf TDI 2003 - mid 2006 (up to MKIV chassis with 020000 at end of VIN) All Jetta TDI 2002-2005
New Beetle TDI 2002-present
New Beetle TDI 2002-present This relay is located in the plenum chamber ahead of the windshield where the windshield wiper mechanism is located. To get to the relay, you have to remove both wiper arms by removing their plastic pivot caps and 13mm nuts. Then you remove the plastic plenum cover below the windshield. The relay is held down with a 10mm nut. Click here for a pic of the Glow Plug Relay mounted in cowl area.

This is an Aggravating One 2003 TDI Jetta Glow

The Glow plug Control Module is right out there in the plenum under the windshield wipers on the drivers side. I had to use a puller to remove the Wiper arms and it is a nuisance to get to the thing. The correct number for the control module is 038-907-281-C. Those of you waiting to hear a click from it are going to have a long wait for it is all electronic. It appears to me three Power Transistors do the work of switching power to the 4 glow plug circuits. There are a couple of computer chips in the middle and the thing appears to have all sorts of circuitry on the printed circuit board. My guess is that it compares the current draw of the 4 glow plug circuits. I am curious that someone in an earlier post said something about using an inductive pickup on the glow plug circuits. I do not think an inductive pickup will work unless the voltage is either pulsed DC or AC - so possibly the transitors provided a pulsed voltage to the glow plug circuits - just speculating.

It is a rather arcane device.

Anyhow - I have changed out the glow plugs, replaced the coolant temp sensor and now this cotton picking control module. I do not think I have the problem licked yet. One problem I have is that I can't keep the car in the shop long enough to run down all the different possibilities.

One thing is that it is not throwing a CEL - my guess is that what little current (or none) which goes to the glow plugs is balanced - and so there is no diagnostic for the dang thing not coming on.

the control module has 9 pins

it appears to me that they work thissaway:

D1 and S1 appear to be dummies


the big one - 30 is used as heat sink for the power transitors and may also carry positive voltage.

G1, G2, G3 and G4 would be the glow plug circuits

87 and 37 go to the printed circuit board of the module

all this is based on what i see inside the control module - I have not yet run down the wiring diagram

my thinking of my problem:

may have something goofed up in wiring harness

I just don't know - it is going to take a good bit more tinkering

does anyone know anything additional about the diagnostics for this system and what, if any, role the ECM may have in the process? in other words is this dang glow plug control module making all the decisions about the glow plug system?

If so then I should be able to isolate the problem, maybe, perhaps.

thank you folks so much

Herm: sounds like you need to increase the glow time a bit. I believe there is a procedure for that around here somewhere.....

creed: start a new thread. 30 is always battery. 87 is usually a control input of some sort. ECM should be setting the time based on the coolant temperature. Happen to own a clamp-on inductive DC current meter, so yeah sure ya betcha you can measure the current in the harness without AC current, or pulsed.

weedeater said:

Herm: sounds like you need to increase the glow time a bit. I believe there is a procedure for that around here somewhere.....

Click to expand...

I think it's adaptation channel 13, IIRC. To help confirm, the adaptation channel number is the same number for the GP measuring blocks.

Stock adaptation value is 32768.

Raising the adaptation value above 32768 results in shorter preglow times.

Lowering the adaptation value below stock 32768 results in longer preglow times and also raises the temp threshold (i.e., it doesn't have to be as cold) for the ECU to start giving preglow.

I think the lowest adaptation value that the ECU will accept is 32468, IIRC. 32650 or 32700 are good values to try. I'm using 32700.

I found this thread by doing a search on "J370" which is the control module for glow plugs. I recently aquired a 2002 Jetta TDI (automatic ) and found that is was extremely hard to start, but once started, it ran great. The first thing I did was to check the timing and found it slightly advanced, but well within the accepted tolerance. Next, I looked for the glow plug relay. As many have discovered, there is none in the 2002 and above. A check of the Bentley manual showed the J370 controller. Then, I tried the trick of unplugging the temperature sensor. Sucess! The glow plugs stayed on and the engine started right up. I tried a new sensor with no sucess. I also checked the glow plugs and each read about 0.9 ohm. I want to think that the controller is bad, but I hate to waste money on a new one only to find that it is not the problem.

So, I did some searching on tdiclub and found this thread among others. In particular, I noted the previous message by David Sterrett on how to change the glow plug time. My enthusiasm quickly turned to disappointment when I found that the information was faulty. When I came back to the message, I saw that he was quoting things from memory, but he was very close. It is adaptation channel 12 (the same as in the GP measuring blocks - that is the hint that gave it away). The default value was 32768 as stated. I tried a new value of 32650 as suggested. I expected the time value to change when I saved my new setting, but it did not. I exited the adaptation mode and shut off the ignition switch. Upon turning the ignition back on, the glow plug light stayed on for about five seconds and the car started right up. The outside temperature was only about 50 degree F. Before the change, the light would go out in less than a second.

Next, I checked the result in the measuring block for 12. It gave a bit code of "1011000" which is "post glow" status according to the Bentley CD. More important to me, the time showed "5.3". I'm assuming that is in seconds.

So, I think my problem is solved, but I wonder what is going on. Did the previous owner replace the glow plugs with the wrong kind? I saw some reference in another thread to this being a potential problem. Is my control module going bad? Any ideas out there?

A special thanks to David!!! Even though the information was not quite right, it led me to the answer.

Windy Gregory
Vee Dub Motors
Kevil, KY
http://www.VWupdate.com

Glow Plug Module?

I had a PO674 code indicating glow plug #4 circuit problem. I have read several of the threads on the GP's and went through the procedures. I found all plugs reading .8 Ohms. Verified voltages. Swapped plugs 1 & 4. Same code. So I pulled the GP module 038 907 281 C checked circuit to each GP and everything reads OK. Called dealer to check on part and they stated that my VIN should have 038 907 281 A designation. But they cannot tell my why or what the difference might be. They want $109 for the module in stock. I pulled the module out and drove without it and got a PO684 code which indicates a comm problem with the module. I was hopeful at first that the ECM would not set a code for the missing module. I need to get this car through the emissions test. Anyone got any feedback on this change of part number? I think that the module could be bad but I would hate to buy it and still get the same code.

Very interesting thread!

cabzjam1 said:

I had a PO674 code indicating glow plug #4 circuit problem. I have read several of the threads on the GP's and went through the procedures. I found all plugs reading .8 Ohms. Verified voltages. Swapped plugs 1 & 4. Same code. So I pulled the GP module 038 907 281 C checked circuit to each GP and everything reads OK. Called dealer to check on part and they stated that my VIN should have 038 907 281 A designation. But they cannot tell my why or what the difference might be. They want $109 for the module in stock. I pulled the module out and drove without it and got a PO684 code which indicates a comm problem with the module. I was hopeful at first that the ECM would not set a code for the missing module. I need to get this car through the emissions test. Anyone got any feedback on this change of part number? I think that the module could be bad but I would hate to buy it and still get the same code.

Click to expand...

Yes the dealer is correct. The C module is for '04 model Jetta and your profile says you have an '02. The A module is for 02-03 model years.

The modules and glow plugs are different between the 02 and 04 model years. The ceramic glow plugs in 04 operate at a lower voltage and have a different resistance. Thus the control modules have to be different to operate them and monitor their condition.

Glow Plug Module.

My dealer has the A module in stock but the parts tech told me he would stay with the C module that I removed from car. They have no idea what the difference between the two are. So I will buy the correct A module. Now about those GP's. I wonder when the guy before me had the GP's worked on if the service department put the correct GP's in the car? What number should I being looking for on my GP's. Or a specific resistance I should see on the GP's. Mine read 0.8 Ohm from GPModule to GP's. Thanks hope to get this resolved asap.

Glow Plug Module.

Put in A revision module today and great success. So far.
Got car through emissions. I did take some readings from both modules if anyone wants what little info I have. The resistance of the A module was about half what the C was. However my old C module showed no resistance from D1 to ST which I am assuming is the com portion of the module? Anyhow. Thanks for the info. Now onto next project or repair whichever comes first.

Is there a way to test the Cold start device?

Ok where can i find the coolant glow plug relay?because i have know power at the plugs even with the temp sensor unplugged.

thanks wayne

It's probably under the dash somewhere. I don't think the CTS has anything to do with the Coolant Glow Plugs. I believe the CTS is only for the engine GPs. AFIK, the Coolant GPs are controlled by the ECU.

And the ECU activates them depending on engine temperature. There are two relays for them. They're in a box just behind the MAF and next to the brake fluid reservoir, attached to the back wall of the engine compartment.

Why do you ask about the coolant glow plug relays?

I have no power at them even when i unplug the ect sensorand i have code 19460 and 19462

wayne

wkobe said:

I have no power at them even when i unplug the ect sensorand i have code 19460 and 19462

wayne

Click to expand...

I did a search for 19460 and 19462 found this for both. Sounds like the relay may be bad.

or the 50A fuse on top of the battery is blown or has a loose connection.