Posted this on the ECM topic and haven't received any views or replies. I was looking through the arap code and noticed that it has a/c control paramaters. What pins are needed to be used on the 165 ECM to allow it to control the A/C compressor.

 

ECM does not control the A/C Compressor. However, when the AC circuit is grounded, the ECM is sent input (AC Commanded on switch) so that it can adjust items such as desired idle speed. There is more to it than that, but that is the gist of it.

 

This is the code for the A/C control $6E mask 165 ECM
Just need to figure out which pin is used to control the relay.

;==============================================
; A/C CLUTCH TABLES & PARAMS;
;==============================================

LC564 FCB 255 ; 99.6%, IF TPS GT THRESH DISABLE A/C
; (MUST BE LC564-16 TO RE-ENABLE)
;
LC565 FCB 255 ; 99.6%, IF PLUS DIFF TPS GT THRESH, DISABLE A/C
LC566 FCB 0 ; 0 sec's, DISABLE A/C CLUTCH n SEC AFTER IF DIFF TPS
;
LC567 FCB 1 ; 100 msec, DELAY FOR CLUTCH ENGAGE
LC568 FCB 1 ; 100 msec, DELAY FOR CLUTCH DIS-ENGAGE
; arg = msec * 100
;
LC569 FCB 255 ; 150c COOL, IF COOL GT THRESH, DIS-ENGAGE CLUTCH

 

I am using using $6e (89) code on an earlier (86) 165 ECM & vehicle. I do not believe that we have the hardware necessary for those parameters to affect anything. Anyone, please correct me if I am wrong.

 

The A/C compressor control uses the same output pin as the TCC. It is option selectable as to what logic controls that pin. So, if no TCC control is required, then the A/C compressor may be controlled.

RBob.

 

Excellent that is what I wanted to find out.