Code 24 displays now that the swap is complete. I believe this to be idle air control. I cleaned the old unit, then eventually replaced it. Ive checked voltage at the connector and the black wire (post "C") is always grounded, the center wire yellow/red (post "B") is constant 12+ volts, and the pink wire (post "A") has 12+ volts for a minute then gets switched to a ground.

 

I believe that to be working correctly, so what could be the issue? Every once in a while it turns off until it idles for around ten+ seconds. Car seems to run perfectly besides that code.

 

Another question. What does the white wire on connector F47 at the ecu pin 18 do?

Something I recently ran into with a Vanagon conversion as well.

 

Anybody ever look in the 90 and 91 FSM's about the IAC.

 

Ever notice that the IAC valve and circuit are different between Manual and AT cars.

 

The Auto IAC has the 3 pins. Power is supplied to one wire, thorugh the Ignition relay, not the ECU, while the others are duty controled by the ECU to balance the *open* and *close* circuits.

 

The Manual IAC has only 2 wires. Power goes to it from the ECU through one wire (that would be a ground side of the Auto circuit), and ground is controlled by the other. Direct from ECU, no external power source. There is only an *open* circuit on the MT valve.

 

 

So back to the point. The Vangon had a code for "24" IAC. Well, here's the deal. The donor car for this swap was a 90 legacy Automatic. 3 pin IAC. Now the guy who did the swap (very professional) cut the Tran I.D. wire at the ECU to designate manual. FIne on 92+ ECU's used in swaps. But not on these first 2 years(90,91). Problem is, now the computer expects to see a 3 wire IAC. Hence the code. I am betting that this is what you are dealing with tturnpaw.

 

I see 3 options:

 

1: Ground the Trans I.D. pin for automatic. All other things correct the engine should still idle well. Did this to the vanagon for a temp fix.

 

2: Install a 92-94 ECU. These years MT and Auto used the same 3 wire IAC. Then you could cut trans I.D. wire to designate MT without the IAC code.

 

3: Install a 2 pin IAC from a Manual car. Connectors and wiring remain the same. But once you have a 2 pin IAC on there, the ECU can be I.D.'d to be a manual with no code.

Edited May 24, 201015 yr by Gloyale