I was having problems with the CIS system in my 83 245T wagon back in November. The original problem was that the car would not idle when cold. All signals going to the ECU seemed correct, and the air control valve and throttle switch were both in good working order.

I got my hands on another CIS ECU, swapped out the questionable one, and the car idles beautifully now. I have included my original post for documentation, but just wanted to share the solution and thank those of you from the board that offered all the good advice.

-Scott

>>>>>>>>>ORIGINAL POST<<<<<<<<<<<

My 83 245T won't idle when the engine is cold. Warm idling works fine.
I have done a lot of research on the CIS system in the car, and have followed the procedure in this document:
http://oregonstate.edu/%7Eerdts/kjet/docs_green.html
as well as the bentley manual, at least related to the electrical parts. I have not done a vacuum test or cleaned the throttle body, which may be the problem. However, when testing the system electrically, everything seems fine:
1. coolant temp sensor increases resistance with decreasing temp as read at ECU
2. The throttle switch is working properly as read at the ECU
3. When I connect pins 5 to 2 and 4 to 1 on the ECU, the air control valve opens completely, sending engine speed up to 2500RPMs

When I ground the test wire (blue/white), nothing changes to the idle speed (no decrease in engine speed when warm).

What would be the next logical step for me to take here? Clean the air control valve or throttle body or something else? It seems that the ACV should be working, when tested it did respond... Since all the electrical systems seem to be in good working order, could it be the ECU?