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  View original topic: 1pin to 4pin Coolant Temp Sensor Wiring for mTDI conversion Page: 1, 2  Next
AKAvant Tue Jul 21, 2015 11:24 pm

I recently swapped a 1z into my 1982 diesel Vanagon using the mTDI injector pump from a 2000 VW LT van. Almost no new wiring was needed but I do need to figure out how to adapt the old single wire setup for the coolant temp sensor to the 4-pin sensor on the 1z. Anyone have any experience with this? I still haven't found a pin-out description for the 4-pin sensor.
Here's a video of the first drive sans exhaust.
http://vid305.photobucket.com/albums/nn213/Disher0...kgvcdv.mp4

Vanagon Nut Wed Jul 22, 2015 1:35 am

edited: It sounds like your coolant sensor has the temp gauge and ECU sensors built into one housing. Search 1.8T sensor pinout here? OR, google your engine block code and ECT diagrams? The 1z ECT plug will have a number at each pin that corresponds to the 1z Bentley diagram.

Determine which pair of ECT sensor pins you need, connect one to ground the other to your coolant gauge +
1982 diesel Vanagon Bentley diagram, (P97.38 ) shows a blue-yellow wire from the temp sensor to T3C (behind dash) to wire 6 at the T14 connector to cluster. This appears to be the + wire from the OEM sensor.
Double check this but this is what I see.


Neil.

Waldi Wed Jul 22, 2015 5:42 am

http://www.motor-talk.de/forum/aktion/Attachment.html?attachmentId=719242

You have to put on pin 1 mass than you can connect on 3 the water temp gauge.
If it works than ok, if not try this on pin 2 and 4.

The other 2 pins should work same for glowing plugs.

If you want to connect your electric water pump, you need another sensor on the zylinder head.

svenakela Wed Jul 22, 2015 3:43 pm

On the conversions I've made I have taken the coolant sensor from the old engine and made up a small adapter.



AKAvant Wed Jul 22, 2015 4:03 pm

Very nice, how did you do that?

?Waldo? Wed Jul 22, 2015 4:16 pm

I imagine he used a lathe and tap. It's a really nice solution.

I've used the earlier I4 aluminum coolant flanges. I don't like the later plastic ones much. Some creativity is required for the aluminum ones due to the different attachment angle at the center of the head.

Zeitgeist 13 Wed Jul 22, 2015 5:15 pm

I can't remember diagnosing those old style coolant sensors, but don't they need to be grounded to the block?

Vanagon Nut Wed Jul 22, 2015 9:35 pm

svenakela wrote: On the conversions I've made I have taken the coolant sensor from the old engine and made up a small adapter.



nice.

could the OP use a 2.1 WBX 2 pin temp gauge sensor? It might be the same dimension as the 1z 4 pin sensor? I've read that other VW's use the same connector as 2.1 does. This would make wiring pretty easy.

Neil.

rotaecho Tue Apr 26, 2016 8:03 pm

I'm actually visiting this now on my AHU mTDI conversion. This is for trying to simplify the coolant wiring/sensor for the mTDI build.

The parts are ordered and I am trying to swap a 1.6na p/n 068121133M flange in place of the AHU 028121132A flange.

This would give me the simple coolant sensor setup than the bulky plastic monster the AHU has.

Also, I am trying to swap the AHU flange 028121145 (Flange With Glow Plug Mounting) with a 1.6na 068121145K one.

I'm not sure of the creativity tweak Andrew speaks of yet. I haven't mounted it on to see / visualize what he's talking about.

It just like him, I didn't like the plastic flanges of the AHU and how bulky they are.

Waldi Wed Apr 27, 2016 2:35 am

You can use the late AAZ 4 pin sensor.
There you have temp gauge and pre glow signal.

rotaecho Sat May 07, 2016 1:47 pm

That's slick! Do you have one to sell?

svenakela wrote: On the conversions I've made I have taken the coolant sensor from the old engine and made up a small adapter.



rotaecho Sat May 07, 2016 1:52 pm

So, I have the AHU (used engine) next to the long-block I'm building up.

In the photo below is the 1.6na 068121133M flange against the AHU engine. It looks like it'd interferrier with the injector lines. What creativity did you use to get this to work for you Libby? Did you bend the injector lines?



I really like that adaptor made for the older style with the AHU 028121132A flange (which I found an aluminum version online of).

Thanks for any insight!

?Waldo? Sat May 07, 2016 2:50 pm

There isn't any interference with injection lines, but the new angle means that the bypass hose is too short. I added a coupler and an angled section of hose.

rotaecho Sat May 07, 2016 3:05 pm

Thanks Andrew,

It looked like it'd interferer with the IP lines, nice to know it wouldn't.

Nice tid-bit thanks!

Andrew A. Libby wrote: There isn't any interference with injection lines, but the new angle means that the bypass hose is too short. I added a coupler and an angled section of hose.

westyventures Sun May 08, 2016 8:33 pm

Waldi wrote: You can use the late AAZ 4 pin sensor.
There you have temp gauge and pre glow signal.

One of the few times I totally agree with Waldi. :wink:

The AAZ sensor is accurate for the gauge + the glow plug relay. Why make it more difficult and expensive when the sensor does the job perfectly?

rotaecho Sun May 08, 2016 9:04 pm

forgive my ignorance here,

But in trying to duplicate the 1.6na glow plug setup for the mTDI AHU, I thought the glow-plug sensor was done off the end of the block with (p/n 068121145K) or similar from the 1.6na? Since the flange on the AHU (p/n 028121145) with the coolant glow-plugs aren't needed.

Would this just turn into another "additional" sensor where the late AAZ sensor in the AHU (028121132A) flange would handle both conditions (glow-plug / coolant temps) with that single sensor?

Thanks for the clarity, just trying to understand it.

westyventures wrote: Waldi wrote: You can use the late AAZ 4 pin sensor.
There you have temp gauge and pre glow signal.

One of the few times I totally agree with Waldi. :wink:

The AAZ sensor is accurate for the gauge + the glow plug relay. Why make it more difficult and expensive when the sensor does the job perfectly?

westyventures Sun May 08, 2016 9:32 pm

rotaecho wrote: forgive my ignorance here,

But in trying to duplicate the 1.6na glow plug setup for the mTDI AHU, I thought the glow-plug sensor was done off the end of the block with (p/n 068121145K) or similar from the 1.6na? Since the flange on the AHU (p/n 028121145) with the coolant glow-plugs aren't needed.

Would this just turn into another "additional" sensor where the late AAZ sensor in the AHU (028121132A) flange would handle both conditions (glow-plug / coolant temps) with that single sensor?

Thanks for the clarity, just trying to understand it.



The AAZ sensor is two sensors in one - for temp gauge and for glow relay. The original AHU sensor in this spot was for temp gauge and ECU temp sensor. The AHU end of cyl. head flange can just be used as-is, no worries with leaving the coolant plugs in place.

rotaecho Sun May 08, 2016 9:44 pm

Thanks. I also reread the URL Waldi posted. I'll revisit my coolant temp sensor idea. The later AAZ temp sensor (need to dig that p/n) may be the way to go for this. I can use the cylender head alone then.

rotaecho Sun May 08, 2016 9:50 pm

Would the proper AAZ later coolant sensor p/n be: 357-919-501A ?

westyventures Sun May 08, 2016 10:46 pm

357 919 501
green ring



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