View Full Version : AC Help: USDM Alltrac with JDM ecu

04-18-2007, 03:24 AM
'91 USDM AllTrac running a JDM ecu.

Now, I know that the JDM ecu uses different wiring to actuate the AC, I do not however know what wire(s) need to be switched or to where.

Now that I have recharged my AC, and the system is pressurized and will now properly actuate, the ecu is throwing code 51. (AC/TPS) :ugh:

I would like to know how to make the JDM ecu work with my AC correctly.

I'm sure that SOMEONE on here has done this successfully. Instructions would be great, pictures and a write-up would be phenomenal! :bowdown:


04-18-2007, 04:27 AM

04-18-2007, 08:22 AM

04-19-2007, 06:16 PM
I need this fixed...

04-19-2007, 06:35 PM
I'm going to be wanting to know how to make this work very shortly aswell, I would like to keep my ac for the next summer.

04-19-2007, 06:37 PM
This might help.


04-20-2007, 04:46 AM
Checked it out, no comparo between '91 USDM and '91 JDM.

Do you guys have any clue as to which pins would need to be switched?

04-21-2007, 12:16 PM
Bump...really need some help here guys. :)

04-21-2007, 03:51 PM
I havn't looked into this yet.
I do intend to, I have a JDM ECU in my cat as well.

I believe Lagos looked into this last summer or fall.
From what he said, the JDM ECU needs the JDM AC computer to work right....
It's not just swapping pins [there are only 2 or 3 that are for the AC], the actual way it's turned on is totally different.

04-21-2007, 10:10 PM
ok, I see. Let me know what you find out. Glad you're still alive. Good luck with your ASE tests and your finals.

The Captain
07-09-2007, 11:53 PM
Anybody figure this out yet?

07-10-2007, 12:17 AM
John, yours doesnt work either?

Why not just hardwire the AC actuator on the compressor to a relay thats wired into the button for the switch that gets power if the fan is on, so that way, it works as it is supposed to, in terms of the button working, and turning the compressor on and off so the ac blows cold?

I know people have done similar wiring as this to get their AC to work.

07-10-2007, 12:30 AM
Reading on the MR2 boards, there is something about a tach signal the JDM Ecu is looking for from the ignitor that needs to be fixed, and there is a wire that isnt needed that needs to be clipped and relocated.

Something to do with that tach signal to the ac amplifier to get it to turn it on though.

07-10-2007, 01:48 AM
wow... Hi Luni ! :D

The Captain
07-10-2007, 02:29 AM
Well, I haven't tried the ECU swap yet. I'm waiting for my big dyno day when I get all my new goodies installed. I've been reading the post and found this to be an issue. I wanted to head this one off at the pass before I took the plunge. Gotta have AC here in the south!