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