AHU wiring...do I need these things?

I've got the engine and trans securely bolted into the sidekick...now I'm starting to look at the wiring mess. A fellow TDIer was kind enough to email me the pinout and I'm thinking (read: hoping) that there are a few things I can do without. So, do I need the following?

pin 17 clutch switch
pin 20 brake light switch
pin 28 A/C relay (car has no A/C)
pin 34 and 35 cruise resume and set (no cruise)
pin 37 A/C on switch
pin 44 brake light
pin 66 cruise switch on

Can I just remove these wires from the loom or might this cause problems? My biggest concern is the clutch switch...not sure how the ECU uses that signal. I'm using the stock starter and ignition that is in the sidekick and it seems to take care of things fine. (ie no starter allowed to turn without clutch depressed)

Thanks in advance for the advice!

I like simple problems like this one.

Just ground Pins 20 and 44 to the Brown/Blue sensor ground wire. These will prevent the ECU from applying throttle input to the pump if not grounded.

Pin 17 disables the cruise if you disengage the clutch, while 20 and 44 disable cruise if you step on the brake.

Pin 44 is also used to monitor brake light bulbs and flash the GP light if they are out.

The rest can be removed or ignored.

Thanks! That helps a lot...It doesn't look too terribly complicated and having help with questions like this makes it tons easier.

I'm stoked! I have another sidekick with an AHU and a mechanical IP. This one will definitively put to rest the debate on mechanical vs electronic.

Don't 20 and 44 work opposite each other (NO and NC)? If you ground both the cruise control will not work and the car will also detect conflicting info and flash the GP light at you every 5 minutes you don't step on the brake.

Pin 20 is grounded through the NC contacts of the switch. Pin 44 is effectively grounded through the brake light bulbs, but goes to +12V when the NO switch applies power to the lights.

The ECU will be quite happy with this arrangement, and will never know the brakes are applied. It will be dangerous using cruise in this setup as the brake will not disable cruise.

If you don't ground both, you will have to connect both switches or the ECU will detect a conflict and start flashing the GP light as well as set a DTC for an improbable brake switch condition.

Ok...back at it.

So in the harness there are a lot of 'extra' wires that go to white harness ends that look like they belong inside the car. I'm not exactly sure what they go to, but it looks like they may not be necessary.

My question is: If I have identified all of the 68 wires on the ECU pinout, can I remove every thing else from the bunch of wires? Will these 68 be sufficient to get things running?

Thanks!

bump

I have an AHU on a test stand, and am working on a solution for you. Results should be in later today or tomorrow. This is part of my Ranger conversion, so don't accuse me of being too helpful.

haha, you've already been quite helpful! I'm just at the stage where I'm staring at the harness thinking it would look a lot cleaner if I got rid of the extra wires that aren't specifically listed on the pin sheet...but I'd hate to do something in error. y'know?

Any pix of your build?

Here are some shots of the test stand. That is as far as I have managed to get with the TDI Ranger.

Alchemist said:

Here are some shots of the test stand. That is as far as I have managed to get with the TDI Ranger.

Click to expand...

I'd rename it a "metal frame TDI conversion swap" and call that thing complete!

Back to business.

This should be all that is required to make the engine work in its new surroundings.

ECU T68-42 Black/Violet to relay 109 term 85
ECU T68-38 Black switched power from Ignition Switch
ECU T68-2 Black/Green Tach signal to cluster(optional)
ECU T68-48 Blue/Green Glow Plug Light
ECU T68-60 Yellow/White MIL
ECU T68-61 Gray/White K line to OBD connector Pin 7
Alternator T2a-1 Blue Battery Warning Lamp
Fan Control Module T10-9 Black/Yellow switched power from Ignition Switch
Relay 109 Term 30 and 86 Battery Power
Relay 109 Term 87 Blue/Red

I didn't find a fuse in the relay 109 Term 30 or 87 circuit, but it would be a good idea to use one.

Since I'm not using the VW alternator, I guess I'll have to figure out a way to connect the battery warning lamp to the VW harness.

Also, I intend to run manual glow plugs...any reason this wouldn't work?

Finally, I'm not sure what the fan control module is...any ideas on how to trick the ECU past that one?

Any video of yours up and running on the stand?

TIA!

The warning lamp connects between switched ignition and the alternator to supply some current to get the alternator started. Most automakers did this, so it should be a simple matter to find the corresponding wire in the Suzuki harness and use it.
The VW alternator reports how much load it is handling to the ECU Pin 39 on the DF line Red/Black. Without this signal, you will set a DTC and get a MIL. BTDT.

I haven't tried running the engine without the glow plug relay, so I am not sure if the ECU wants to see it or not. Tomorrow's experiment is to find out what happens. You may get a MIL and DTC for glow plug problems, but other than that it should be fine.

I assumed you would be using the VW rad and fans, and so would need the controller to switch them on and off as needed. If you have some other system for fans, then no, it won't be a problem. Don't worry about the ECU, it doesn't connect to the fan controller.

No video. This started out being something to amuse me and I didn't think of making a big production out of it. Perhaps I should have made a documentary. Its too cold here to run it outside or with the door open, and too smoky to run it with the door closed.

Thanks for the info, you've been an amazing help in this project...!

I hope to get mine going someday here...I just realized it's been almost 8 months since I got the thing...it's been way too long!