ALH TDI pinout.

[vdubspeed]

These pictures are subject to change but I wanted to get the information I have gathered out there. I know there are plenty of people that do TDI swaps beyond just VW people. My goal here is to help ALL TDI swappers get there swaps running as the factory intended.

Please remember though...my donor is from a 2001 Beetle Auto donor and going in a 1984 Rabbit GTI so I'm a little geared toward that thinking.

This is also an evolving set of picture. I haven't even finished the swap yet but I'm close to having the wiring figured out.

And now I present...

ALH TDI wiring Version 1.2

1.1 - change - correct title
1.2 - change - T6/1 Brown - power to ECU when key is on. To pin 121/37 on ECU.

 

[markd89]

Looks like a VERY cool resource

Why is it labeled "AHU TDI-121 TDI Pinout" (not ALH)?

 

[Red_Liner740]

Dude, you're amazing!!

Thats exactly what i need!!

 

[vdubspeed]

Why is it labeled "AHU TDI-121 TDI Pinout" (not ALH)?

Because racecar.

Version 1.1 belongs to you good Sir.

 

[AndyBees]

Awesome info! Wow! I spent tons of hours deciphering the Bentley manual electrical schematics and applying it to the real world.

Now, I have all that info in Excel Spreadsheet as well as my hand-drawn schematics. I also did mine maybe a little deeper because I am using the Jetta Cluster with most all the bells and whistles as well as the cruise, fuel level, coolant level, brake fluid level, clutch-in to start, etc.

Surely, many will be appreciative of the work you have done. It shows dedication and talent!

Thanks!

 

[hybridfreak]

T10Black/8 gn/ws connects to the clutch pedal switch IIRC.

Very helpful writeup! Thank you!

 

[greengeeker]

Ahem....ECU ground?

Nice work!

 

[vdubspeed]

T10Black/8 gn/ws connects to the clutch pedal switch IIRC.

Very helpful writeup! Thank you!

AH! That makes sense because my donor was an auto

Ahem....ECU ground?

Nice work!

Where we're goin...we don't need ECU grounds

 

[Red_Liner740]

I see a few of the pictures and descriptions have references to "Figure 1"

Would you happen to have a picture or a link to this figure 1?

** NEVER MIND....if i just opened my eyes and LOOKED i would see it in the first picture...duuh.

 

[JFettig]

Nice. I just went through all this myself. You should note that the pin-out on some cruise control stalks and gas pedals are different. I'm putting a 121 pin ALH ecu and harness into my Passat and found that the pin numbers are different.

 

[archemitis]

This post came up just in time for me! Thank you so much! I'm trying to understand what makes the ECU send the ground to terminal 85 on the 109 relay. what tells the computer its time to wake up?
I'm thinking its got to be t121/88 or t121/37. Is there an accessory position for one and an on position for the other?

 

[vdubspeed]

This post came up just in time for me! Thank you so much! I'm trying to understand what makes the ECU send the ground to terminal 85 on the 109 relay. what tells the computer its time to wake up?
I'm thinking its got to be t121/88 or t121/37. Is there an accessory position for one and an on position for the other?

88 wakes up the ECU(key on), ECU then fires back to power supply relay and that in turn wakes everybody else up.

 

[JFettig]

I'm finishing up what I need to do with mine and I'm also stumped on pin 88. I'm not putting this into a MK4, its actually going into a B5 and I have a general idea what its for but don't know any specifics.

This is T14a/10 - load reduction relay.

What does it do? How does it work? What do I hook it up to?

 

[ta79pr]

If a PD, T10w/7 [li/ws] would be the fuel pump relay trigger from the ecu (fuel pump relay (J17 (4/85)). Also, T10w/9 [ge] is the "crash signal" from the airbag module if your target vehicle is so equipped.

 

[archemitis]

This is T14a/10 - load reduction relay.

What does it do? How does it work? What do I hook it up to?

I was wondering about that myself. Pretty sure it has something to do with the ecu getting full power while the starter is cranking. Not needed in my situation... I hope.

Any clue what T121/37 does? Looks like it goes to the ignition accessory position.

Im working on a "stand alone" harness that only needs the ignition switch signal from the vehicle along with clutch, brake and all that... so I can only speak in T121, as I only have two large ecu plugs to play with.

Does the ecu care if the starter is cranking? I havent found any ecu pins that go to the starter, so Im guessing no?

Sure wish there was a bar where guys that knew wiring could go and talk about this stuff and run ides by other like minded individuals... guess this is the next best thing!

Thanks again, this thread got me back into the wiring mode.

 

[archemitis]

AH! That makes sense because my donor was an auto

Did you add a clutch switch wire? Isnt it necessary for cruise? My donor also came from an auto, and this is the first pin I think I need, that I dont have T121/66.

 

[vdubspeed]

No I didn't add a switch for the clutch. My thinking is that the ECU won't care because it thinks it's an auto and won't look for and therefore the ECU will not care.

I am buying another TDI mk4 to part out this week that is actually a 5spd so I'm curious to compare harnesses.

I really don't know EXACTLY what pin 88 is for just yet as I haven't gotten that far. I have read other threads though that have said it's ignition (circuit 15).

All we need is one person who has an ALH swap to confirm how their ECU is powered. I understand how everything else is powered(grnd signal from ECU engages 109 relay)

Thanks,

Jason

 

[AndyBees]

Clarification (not intended to highjack the Thread, but I have received a few PMs)

14a/10 does go to the Load Reduction Relay. However, it also goes on to D75 in the ignition switch. On the way, it goes through Fuse 37 and Splice A80. Splice A80 is where it branches off to the Load Reduction Relay.

In summary, current goes from D75 in the ignition switch, to Splice A80. There it branches into two circuits. One goes directly to the Load Reduction Relay and the other goes to Fuse 37, then to connector 14a/10 and on to pin 121/88 of the ECU. That circuit is only hot when the Ignition is ON. In the start mode, that circuit is dead at both the Load Reduction Relay and Pin 121/88 at the ECU.

I suppose the function of Pin 121/88 can be determined by removing Fuse 37 and see what happens. Apparently there is a need for it to be fused.

I did include the circuit from D75 to Pin 121/88 of the ECU in my applicaton with the use of Fuse 37. From the Donor vehicle, there is no need to use the Load Reduction Relay if you use the receipient vehicle ignition system which already contains that relay.

EDIT: The Clutch switch is not necessary. However, the circuit needs to be completed for the Cruise to work. Right now, I have mine wired directly by-passing the switch because it needs adjusted to be instant. When the clutch pedal is depressed, if the switch doesn't instantly disable the Cruise, RPMs will go up extremely fast .........

 

[greengeeker]

Does the ecu care if the starter is cranking?

No it doesn't.

I have no idea what pin 88 is for - the 80 pin ecu's don't have that wire. All you need to power the 80 pin ecu is the provide 12v to sw/li and ro/li and of course provide ground. Maybe pin 88 is just another wire you need to provide 12v?

 

[vdubspeed]

Today after work I will pull fuse 37 from my brothers stock 2000 Golf TDI.

If it doesn't start...pin 88 requires 12V.\
If it starts...hmmmm...

 

[runonbeer]

I scratched my head over T14a/10 for a long time trying to come up with an elegant way to wire it into my VR6 swap. Eventually I gave up and never wired it. Everything works just fine. Not necessary in my case.

 

[archemitis]

Sorry if i got this going in a hijacked thread sorta direction, but this is good stuff!
Im going with T121/88 and t121/37 wired to "on" position on my ignition switch. They are the only two wires going directly to the ignition from the ecu.
Hoping to finish up an hour or so of soldering tonight then power it up. I have "Torque" on my phone, to look at sensors and stuff before I try to start it.

AndyBees, that cruise situation sounds terrible, especially at highway RPMs! thanks for the warning, sounds like a spring pull brake switch wont do the trick.

 

[vdubspeed]

archemitis - report back with your findings!

 

[JFettig]

I have a 2003 harness with a 4-wire glow plug system in it and a 2001 ECU. The only real difference that I can tell is that one of the wires for this is in a different spot. Do I need to do anything about it, can I move the wire over and will it be fine or do I need to get a 2003 ECU?

archemitis - 37 is what wakes the ecu up from the key.

 

[archemitis]

Yes! I just confirmed this on my own harness. 37 makes the 109 click on, clicks inside the computer, and also something on the pump hums, or hissses for a bit. Got my phone to recognize my ecu! Not sure about 121/88 yet.

 

[greengeeker]

I went back and checked my notes and 88 is just another you need to apply 12V with key on (jimbote posted it a while a go in a swap thread).

 

[vdubspeed]

Awesome. So 37 tells the ECU to come alive. I've been busy parting out another TDI (00 Jetta TDI/5 spd) that my bro needs for a parts car. I'm fortunate to be keeping most of the swap stuff though since he just needs body parts and few other items.

What plug does 121/37 go to?

 

[AndyBees]

Awesome. So 37 tells the ECU to come alive. I've been busy parting out another TDI (00 Jetta TDI/5 spd) that my bro needs for a parts car. I'm fortunate to be keeping most of the swap stuff though since he just needs body parts and few other items.

What plug does 121/37 go to?

Well, according to the Bentley for my '02 Jetta donor car, 121/37 goes thru T6/1 (the brown connector) then to an internal "splice" in the wiring harness (the splice is identified as A104). One branch goes to 14a/8 and stops there (thus no use). The other branch goes to Fuse 29 and from there directly to the ignition switch at D15 (Hot when in the ON position). Technically, you could say the current flows to 121/37, thus, making the ECU come alive when the Ignition is turned ON!

Hope that answered your question.

 

[markd89]

Once vdubspeed finalizes the chart (after all the questions are answered) and we've covered manual trans as well, I'd suggest to make a sticky. The ALH is so popular in swaps that this this is going to help so many people.

 

[AndyBees]

I've been updating all the files/notes on my ALH build/conversion project..... more or less what you would call "as built" drawings and notes. It has been my intent to do something similar to what vdubspeed has done! Considering he has beat me to the punch, I'll not bother!

Markd89, this Thread will make an excellent sticky as you have suggested!