ws6transam.org - Dan's Performance Page

ALDL Description information for these platforms:
2.8 Litre Pontiac Multiport Fuel Injection System (1985 - 1988)
(Pontiac Fiero platform)
160 Baud ALDL operating characteristics:
Data Rate:      160 Baud (All)                     Level:  TTL
Refresh Rate:   1.25 Seconds                    Modes: Normal, 10K,
Stream size:    25 Bytes                                        3.9K,Shorted
Byte Data Name Description
1 MW2 Mode Word 2
2 PROMIDA PROM ID (MSB)
3 PROMIDB PROM ID (LSB)
4 ISSPMP  IAC present motor position
5 COOLDEGA Coolant temperature, A/D counts
6 FILTMPH  Speed in Miles per hour
7 ADMAP Manifold Air Pressure variable
8 NTRPMX  Engine speed in RPM 
    (25 RPM per bit)
9 ADTHROT  Throttle Position, A/D counts
10 INT  Base pulse (fuel) closed loop correction
11 ADO2A  Oxygen sensor minor loop filtered value
12 MALFFLG1 Malfunction flag word 1
13 MALFFLG2 Malfunction flag word 2
14 MALFFLG3 Malfunction flag word 3 
15 MWAF1 Mode Word -- Air/Fuel 1
16 MCU1IO MCU I/O First status word
17 MCU2IO MCU input/output second status word
18 ADBAT  Battery voltage in a/d counts
19 BLM  Block learn multiplier, base pulse fuel correction
20 ALDLCNTR  Oxygen sensor voltage transition counter
21 SAREF+1  Unlimited spark advance 
(Multiply by 1/2.8944 for degrees)
22 EGRDC  EGR Duty Cycle
23 RAWADMAT  Manifold Air Temperature, A/D Counts
24 BPW  Injector base pulse width MSB
25 BPW+1 Injector base pulse width LSB 
 
160 Baud Mode Words & Status Flag Descriptions
Byte Name BCD Description
MALFFLG1 MALF FLAG WORD 1 
Bit     Code    Description 
0       24      Vehicle speed sensor 
1       23      MAT sensor low 
2       22      Throttle position sensor low 
3       21      Throttle position sensor high 
4       15      Coolant sensor low temperature 
5       14      Coolant sensor high temperature 
6       13      Oxygen sensor 
7       12      No reference pulse (engine not running)
MALFFLG2 MALF FLAG WORD 2 
Bit     Code    Description 
0       42      Electronic spark timing monitor error 
1       41      Not Used 
2       35      Idle Air Control
3       34      Mass air flow sensor low 
4       33      Mass air flow sensor high 
5       32      Exhaust gas recirculation failure (EVRV) 
6       31      Wastegate High MAP Overboost 
7       25      Manifold air temperature high
MALFFLG3 MALF FLAG WORD 3 
Bit     Code    Description 
0       55      ADU error 
1       54      Not Used 
2       53      Over voltage 
3       52      CAL pack missing 
4       51      PROM error 
5       45      Oxygen sensor rich 
6       44      Oxygen sensor lean 
7       43      Electronic spark control failure
MW2 Mode Word 2 
Bit     Description 
0       Road speed pulse occurred (6.25 msec check) 
1       ESC active flag (1 = active) 
2       Reference pulse occurred (6.25 msec check) 
3       Diagnostic switch in factory test position (3.9 K) 
4       Diagnostic switch in diagnostic position (0 ohms) 
5       Diagnostic switch in ALDL position (10 K ohm) 
6       High battery voltage-disable MCU solenoid discretes 
7       Old cell flag (Air/Fuel)
MWAF1 FUEL AIR MODE WORD 1
Bit     Description 
0       Low RPM Hysteresis flag 
1       Learn control enable flag (1 = enable) 
2       Low battery IAC Inhibit flag (1 = inhibited) 
3       Quasi-ASYNC Transition flag 
4       ASYNC Pulse flag (AP Flag) 
5       Shared flag: 1st time Closed Loop or slow Rich/Lean
6       Rich/Lean flag (1 = rich, 0 = lean) 
7       Closed Loop flag (1 = Closed Loop, 0 = Open Loop)
MCU1IO MCU INPUT FIRST STATUS WORD 
Bit     Description 
0    Idle Air Control (IAC) stepper coil A (IACA)
1    IAC Stepper coil B (IACB)
2    IAC Stepper coil on/off (1 = motor on)
3    Not Used
4    Vacuum Switch (1 = Vacuum Present)
5    Air Conditioner discrete (0 = A/C enabled)
6    Wastegate bypass control (1 = bypass)
7    Park/neutral switch (1 = in park or neutral)
MCU2IO MCU INPUT SECOND STATUS WORD
Bit    Description
0    A/C Clutch (1 = enabled)
1    Coolant pullup select (0 = 4Kohm, 1 = 348 ohm)
2    Transmission Converter Clutch (1 = locked)
3    COP2
4    Not Used
5    Power steering discrete (1 = active normally open switch)
6    Not Used
7    Not Used

 
 
Description of mode operation
Mode Data Stream Timers Special Functions
20K Ohm Words 1-20 Normal Normal Operation
10 K Ohm Words 1-20 Expired
IAC Reset if RPM>2000 for first time
Integrator reset criteria disabled
Burst knock retard disabled
Bypass RPM and Temperature criteria for ESC enable
Set idle to 1000 RPM
3.9 K Ohm Words 1-20 Expired Backup spark and fuel control test mode
Below 500 Ohm Words 1-20 Expired Diagnostic display mode (check engine lamp flashed with O2 Sensor

 
ALDL Pinout pin assignments
Pin A: Ground Pin B: Diagnostics Enable (Resistance w/rt A)
Pin F: Torque Converter Clutch Lockup Pin C: Air switch solenoid
  Pin E: Derial Data line (TTL)
  Pin G: Fuel Pump prime