Later PCM
----------
??? pwd ID
6C 10 F1 AE 02 80 [XX] 00 00 00 00

'97 PCM
--------
4C 10 F0 AE 02 80 00 00 00 00 00

In the '97 code mode $ae submode $80 has no other parameters and I believe is used to center the IAC.

Code is:
Code:
BANK0:7025 loc_7025:                                                                       ; CODE XREF: VEC_OUTPUT_CMP2:loc_701Ej
BANK0:7025                                 ldaa    M$AES$02P$00                            ; M$AE PID $02 PARAM 0
BANK0:7028                                 bita    #$80
BANK0:702A                                 beq     loc_703D
BANK0:702A
BANK0:702C                                 brset   <byte_7D $02 loc_7040                   ; BIT 01
BANK0:702C                                                                                 ; BIT 02
BANK0:702C                                                                                 ; BIT 04
BANK0:702C                                                                                 ; BIT 08
BANK0:702C                                                                                 ; BIT 10
BANK0:702C                                                                                 ; BIT 20
BANK0:702C                                                                                 ; BIT 40 TX MESSAGE IN PROGRESS
BANK0:702C                                                                                 ; BIT 80 DISABLE BACKGROUND MESSAGES
BANK0:702C                                                                                 ;
BANK0:702C
BANK0:7030                                 bset    <byte_7D $02                            ; BIT 01
BANK0:7030                                                                                 ; BIT 02
BANK0:7030                                                                                 ; BIT 04
BANK0:7030                                                                                 ; BIT 08
BANK0:7030                                                                                 ; BIT 10
BANK0:7030                                                                                 ; BIT 20
BANK0:7030                                                                                 ; BIT 40 TX MESSAGE IN PROGRESS
BANK0:7030                                                                                 ; BIT 80 DISABLE BACKGROUND MESSAGES
BANK0:7030                                                                                 ;
BANK0:7033                                 bset    <byte_B7 $04                            ; BIT 01
BANK0:7033                                                                                 ; BIT 02 GEAR CHANGE IAC STEPS ACTIVE
BANK0:7033                                                                                 ; BIT 04
BANK0:7033                                                                                 ; BIT 08 IAC TIMEOUT STEPS TIMER EXPIRED
BANK0:7033                                                                                 ; BIT 10 PARK/NEUTRAL SELECTED PREVIOUS STATE
BANK0:7033                                                                                 ; BIT 20
BANK0:7033                                                                                 ; BIT 40 IAC LOW SPEED CONDITIONS ?? VEHICLE MOVING ??
BANK0:7033                                                                                 ; BIT 80 AUTO TRANS PARK/NEUTRAL SELECTED FLAG
BANK0:7033                                                                                 ;
BANK0:7036                                 ldab    #$FF
BANK0:7038                                 stab    IAC_POSITION                            ; IAC MOTOR POSITION
BANK0:703B                                 bra     loc_7040

The idle air control system is quite complex. There are a bunch of things relating to shifting of automatic trans from neutral to in gear, air conditioning, perhaps power steering load, various test controls. Also to be considered is the timing of the outputs to the motor. Each step needs to be sent and then a delay before the next step. This is needed to let the motor catch up with the applied state. It is going to take some effort to sort through all this.
-Tom