Glow plug and CE lights

Reddok

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Feb 18, 2010
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Hamilton, Ontario
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'00 Jetta TDI 01M, '02 Jeep Liberty Renegade ALH TDI swap
I'm working on my wiring for my conversion right now and was thinking about the glow plug and check engine light. I had read that the older ALH TDIs had dedicated pins on the ECU for CE and GP lights. I thought I'd check to see if any of the unused pins on my 2002 ALH ECU might be used in the same manner.

I used the output test in VAGCOM and probed the pins on the 121 pin connector and discovered the glow plug light appears to be exposed on pin 40! It is actually wired to the white connector at the firewall (Blue with green stripe wire). I can't verify this 100% as my wiring harness is not in my vehicle yet though.

Unfortunately, I had no luck finding a CE light output. Anyone else have any ideas? There are 3 other pins labeled as unused on the mitchell diagram I have (pin 24, 28 and 47). Any ideas on what these pins? Maybe an RPM signal in there somewhere? I can't check that until I have this running though.
 

markward

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Loxahatchee, Florida
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82 Vanagon and 2011 JSW
On the earlier ALH, the check engine light got a ground from the ECU. The bulb would have been hot with the key on. The Glow plug light is wired similarly. I do not know the later ECU pin outs but they are different than the 80 pin.
 

Reddok

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Feb 18, 2010
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'00 Jetta TDI 01M, '02 Jeep Liberty Renegade ALH TDI swap
any updates on this issue?...I'm facing these exact problems right now as I wire my swap
I used the glow plug output as described above. I've got an Autel Maxitrip now which will indicate if the CEL is on, so that may have to suffice.
 

AndyBees

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Location
Southeast Kentucky
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Silver 2003 Jetta TDI, Silver 2000 Jetta TDI (sold), '84 Vanagon with '02 ALH engine
Obviously you guys haven't been reading my Thread or just forgot! Of course, I've cut and labeled the wiring so that I can use the ALH (2002 model) Cluster in the Vanagon.

I have lists of all the pins on about everything needed to do a conversion!........ECU, Cluster, 14-pin connector, the 5 colored connectors, etc. Practically all of my info come from reseacher/testing using the Bentley manual. Or, if someone supplied me with a list/lists, I verified with the Bentley. No, not fool proof, but I trust my research more than somone else's!

EDIT: Well 'ell! I'm caught off guard here! After all the research, schematic studying, note taking, etc., I never had noticed the Bentley doesn't exactly show which Pins in the Cluster that carry the info for the GP light or the CEL (called a Malfunction Indicator Lamp [MIL] in the Bentley). The lights are so noted and identified as: K29 is the GP indicator light and K83 is the MIL light (commonly called Check Engine Light).........obviously no help to you!

So, excuse me, I need to do some more research!

My ECU pin data is compiled from the Bentley Manual............ 1.9L engine code ALH, from September 2001. So, the pin usage may not be the same as for the 99.5 model.
 
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Reddok

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'00 Jetta TDI 01M, '02 Jeep Liberty Renegade ALH TDI swap
I have all the wiring info as well. But I am not using the tdi cluster. The cel for the tdi is controlled via the bus. There doesn't appear to be a dedicated pin on the ecu for the cel on the ALHs.
 

AndyBees

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Southeast Kentucky
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Silver 2003 Jetta TDI, Silver 2000 Jetta TDI (sold), '84 Vanagon with '02 ALH engine
CEL and GP lights

I have all the wiring info as well. But I am not using the tdi cluster. The cel for the tdi is controlled via the bus. There doesn't appear to be a dedicated pin on the ecu for the cel on the ALHs.
Yes, I believe you are correct. It appears the cel is controlled via the bus.

It has been so long since I did the research and prepared my schematic/drawnings that I just went brain dead for a while!

The ECU pin data I have indicates that pin 40 is an open (unused) circuit. The circuit goes to connector T10w/8 and no farther (dead ends there).

Pins 5, 9, 33, 43....... all are labeled GP on my list. Pins 21 & 22 go to the Relay for preheat coolant GPs. As I recall, one of the circuits is split between to of those GPs.
 

Reddok

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'00 Jetta TDI 01M, '02 Jeep Liberty Renegade ALH TDI swap
So bentley shows pin 40 as open and yet I get a glow plug ground on it. So maybe one of the other pins will have a CEL on it. I wasn't able to find it though. I may try again one of these days once I get my swap up and running without any codes.
 

jimbote

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Jul 10, 2006
Location
spiral arm, milky way (aka central NC)
TDI
Tacoma 4x4 converted to TDI
so pin 40 it is!!....OK at least that part is solved...I'll do some research on my own to see where I can pull a CEL as I'm NOT using the VW cluster but using the factory toy cluster ...there has to be a way !!:)
 

AndyBees

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Southeast Kentucky
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Silver 2003 Jetta TDI, Silver 2000 Jetta TDI (sold), '84 Vanagon with '02 ALH engine
As I stated above:

"The ECU pin data I have indicates that pin 40 is an open (unused) circuit. The circuit goes to connector T10w/8 and no farther (dead ends there)."

During my research (chasing circuits, making notes, drawings, etc.), using a multi-meter, I doubled checked all the circuits going to the ECU. The T10w/8 connector(White Connector with 10 pins), is where that circuit stops. There is no wire on the receptical side of T10w/8 (Pin 8)...........so, that circuit goes no farther.

Now, checking Pin 40 at the ECU might show some Ohms number due to where the circuit goes internally!

Edit: I reviewed the ECU pin list last night. Here are the Pin numbers that go to the ALH Cluster (complete circuit from ECU pin):

ECU#6 goes to connector T10w/2 then to Green Cluster connector T32a/20 (Can-1),
ECU#7 goes to connector T10w/3 then to Green Cluster connector T32a/19 (Can-h),
ECU#16 goes to connector T10/1 then to Green Cluster connector T32a/5,
ECU#20 goes to connector T10/6 then to Blue Cluster connector T32/3,
ECU#27 goes to connector T10/9 then to Blue Cluster connector T32/11.

The research shows that the last one (ECU#27 to T32/11 at Blue) has no use!

So, there are three green and one blue from the ECU to the Cluster that have a function of some sort!
 
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Reddok

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'00 Jetta TDI 01M, '02 Jeep Liberty Renegade ALH TDI swap
This is how I did my glow plug light: http://forums.tdiclub.com/showpost.php?p=3277625&postcount=87

I used a similar method for the alternator charge light.

It would be nice if I could find one of the pins on the ECU that acted the same way to use to trigger the CEL, but it's low on my priority list. I have to get my intake piping connected so I can fire it up and set my IP timing after the timing belt change.
 

jimbote

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spiral arm, milky way (aka central NC)
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Tacoma 4x4 converted to TDI
my ecm is from a Y2K jetta...so some of the pinouts may be different...I do know the glow functions are not interchangeable between Immob II and III ...as the Immob III has the glow module in the rain tray and the Immob II has the glows split between a smart relay and the ecm....i'll post my pinout findings this afternoon (already taken notes)
 

Reddok

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'00 Jetta TDI 01M, '02 Jeep Liberty Renegade ALH TDI swap
my ecm is from a Y2K jetta...so some of the pinouts may be different...I do know the glow functions are not interchangeable between Immob II and III ...as the Immob III has the glow module in the rain tray and the Immob II has the glows split between a smart relay and the ecm....i'll post my pinout findings this afternoon (already taken notes)
Mine is from a 2002, I believe I have the smart relay for the glow plugs and immo3, but I don't have a cluster or a keyfob so I'm not sure about the immo version. I'm really wondering what pin 27 does if it goes to the cluster. It was one of those pins my wiring diagram didn't detail. There are quite a few outputs on the ECU that aren't used. I tried toggling the CEL in VAGCOM and probing all the outputs looking for a flashing ground, but had no luck. I will try again when I have some time now that the harness is completely installed and powered in the Jeep.
 

AndyBees

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May 27, 2003
Location
Southeast Kentucky
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Silver 2003 Jetta TDI, Silver 2000 Jetta TDI (sold), '84 Vanagon with '02 ALH engine
2002 Cluster, ECU, etc.

Mine is from a 2002, I believe I have the smart relay for the glow plugs and immo3, but I don't have a cluster or a keyfob so I'm not sure about the immo version. I'm really wondering what pin 27 does if it goes to the cluster. It was one of those pins my wiring diagram didn't detail. There are quite a few outputs on the ECU that aren't used. I tried toggling the CEL in VAGCOM and probing all the outputs looking for a flashing ground, but had no luck. I will try again when I have some time now that the harness is completely installed and powered in the Jeep.

All the cyphering I've been doing is in reference to a 2002 Jetta TDI (Mr. GutWrench's engine)......... I copied (for work purposes) the wiring schematic pages from the B Manual, typed notes on all the circuits by item (ECU, Cluster, 5 colored connectors, 14-pin connecter, etc.). So, that's where all my info comes from along with actually double checking all the circuits that I plan to use with a multi-meter.

EDIT: The Cluster T32/11 Pin (circuit from the ECU pin 27) does actually go inside the Cluster according to the Bentley schematic. However, a triple asteric (***) says thru April 2002. The reason I say it has no function/use is it was identified as "open" on a list I got from a very reputable TDI guy that had done a converison ..... info posted in the Yahoo Groups (TDI - Conversions).

Also, my wiring harness has the GP Relay separate .....in otherwords, the relay is not plugged onto the relay panel above the fuse panel. I guess that was typical for some of the ALH MKIVs.
 
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jimbote

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spiral arm, milky way (aka central NC)
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Tacoma 4x4 converted to TDI
on my swap I'm using pin 27 of 121 on the ecm for the tach output directly to the tacoma cluster tach wire...runs the tach perfectly....I'm convinced that pin 24 of 121 is the CEL....even though it may be via can in the later cars I'm sure its just a vistigial remnant of the older ECMs...probably used in industrial apps or in markets/vehicles where can is unnecessary
 

jimbote

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spiral arm, milky way (aka central NC)
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Tacoma 4x4 converted to TDI
CEL found!!

OK...pin 24 of 121 white with blue stripe is definately the MIL output from the ecm...I do have an issue however....my 12v led is always dimly lit when key on....it brightens and dims when testing with vagcom in output tests...but never fully goes out:confused: ...I could have some backfeed issues from my wiring....not sure....has anyone else experienced this? ... maybe because I have outstanding codes?
 

Reddok

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'00 Jetta TDI 01M, '02 Jeep Liberty Renegade ALH TDI swap
OK...pin 24 of 121 white with blue stripe is definately the MIL output from the ecm...I do have an issue however....my 12v led is always dimly lit when key on....it brightens and dims when testing with vagcom in output tests...but never fully goes out:confused: ...I could have some backfeed issues from my wiring....not sure....has anyone else experienced this? ... maybe because I have outstanding codes?

My glow plug light off of pin 40 behaves the same way... Not sure why either. I'm thinking it may have something to do with current leakage through the switching transistor in the VW ECU.
 

Reddok

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'00 Jetta TDI 01M, '02 Jeep Liberty Renegade ALH TDI swap
is it possible by increasing the ohms on the resistor this can be alleviated?
No, that will just reduce the current through the LED. Not sure if maybe a zener would work. I'm not a circuit design expert by any means. I'm going to ask an EE friend of mine and see what he thinks.
 

Reddok

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'00 Jetta TDI 01M, '02 Jeep Liberty Renegade ALH TDI swap
So my friend said there is a voltage difference between the VW ECU and the cluster voltage for driving the LED. He said the easiest solution is to use a relay. Relay is driven by 12V and the VW ECU pin 40 or 27 grounds it to turn it on. The relay closes a circuit that grounds the LED driver circuit to cluster ground. But that depends on the ECU being able to handle the current of the relay (Which it may not).
 

jimbote

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spiral arm, milky way (aka central NC)
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Tacoma 4x4 converted to TDI
hmmm....I think not....I've heard the ecu is not even supposed to handle an incandescent gauge bulb....maybe I'm oversimplifying things but what If I pulled the voltage from the ecu power wire?
 

jimbote

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spiral arm, milky way (aka central NC)
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Tacoma 4x4 converted to TDI
OK...warning lamp glow solved (sort of)

since Reddok posted that the voltage difference between the ecm and cluster was causing the CEL to stay on (albeit dimly) I decided it might be a good idea to use the ecm's own reference voltage to solve the issue...so I used 11 of 121 (brown/white, fan control module wire) which shows a little over 3 volts with key on....voila!! it worked...cel only comes on when tested with output in vagcom....no dim output otherwise...it could be I can source another wire in the myriad...but for now this is what I'll use for the MIL and glows :) "EDIT" ....OK during testing using the brown/white pin11 wire worked great but shortly after startup the LED turned off...seems that voltage is only present a short time after cranking but remains while key on engine off...back to sourcing a pin I can pull reference voltage from:rolleyes:
 
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turbocharged798

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May 21, 2009
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Ellenville, NY
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99.5 black ALH Jetta;09 Gasser Jetta
You shouldn't really run a regular bulb off the ECU. It is designed to switch low power LEDs. Even then, it usually goes through some fancy circuity and not just straight to the LED in the cluster.

I am surprised there is even CEL/GP outputs on the ECU. The only MK4 that ever had CEL/GP going direct to the cluster was 99.5 cars. The rest of them go straight over can-bus.
 

jimbote

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spiral arm, milky way (aka central NC)
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Tacoma 4x4 converted to TDI
You shouldn't really run a regular bulb off the ECU. It is designed to switch low power LEDs. Even then, it usually goes through some fancy circuity and not just straight to the LED in the cluster.

I am surprised there is even CEL/GP outputs on the ECU. The only MK4 that ever had CEL/GP going direct to the cluster was 99.5 cars. The rest of them go straight over can-bus.
im using an led for the CEL and plan on it for the glows...just have not gotten that far yet....again i think vw may have included these outputs for industrial apps where can was not required....these same pins/wire colors still present themselves even in the newer (01-03) ecu's also...so I think it can be safe to assume they have the same function
 

jimbote

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spiral arm, milky way (aka central NC)
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Tacoma 4x4 converted to TDI
cel functionality...

not 100% sure what is going on with the cel...but it "appears" functionally different than the can controlled cel....the cel will light for 30 seconds after starting but then turns off...so now it appears voltage is always present at the brown/white wire but the ecm cuts ground (after 30 seconds)...I still need to wire up my glows to see if the light will go out instantly as that is the only code I have at the moment...or I may test on my beetle
 
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Goldguru

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Jul 20, 2010
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BC Canada
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98 tracker conversion AHU
02 jetta TDI uses Pin 16 ecu for engine controller CEL. to pin T32a/5 Gray /white wire @ cluster so wire in your led to 16 ecu all Be good.
 

LukeWilson

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Toyota 4x4 TDI, 2004 Allroad TDI
I have the same problem with my glow plug light, I have a 1Z 68-pin ecu though. I have also noticed that i get a code from it, something about "glow plug open or short", i'll have to scan it again to get the exact code.

Luke
 

Goldguru

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98 tracker conversion AHU
I have the same problem with my glow plug light, I have a 1Z 68-pin ecu though. I have also noticed that i get a code from it, something about "glow plug open or short", i'll have to scan it again to get the exact code.

Luke

pin 48 on 68 JB ecu here for glow period warning lite..1 side of bulb to ign on & other 2 pin 48 ecu
 

LukeWilson

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Toyota 4x4 TDI, 2004 Allroad TDI
That's how i have it wired and it does work fine, but as other people have said, there is some kind of voltage leak because the light doesn't fully go out.
 
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