ws6transam.org - Dan's Performance Page

ALDL Description information for these platforms:
 Pontiac Throttle Body Injection System 
1983-1986 1.8 Litre & 2.5 Litre Pontiac
 
160 Baud ALDL operating characteristics:
Data Rate:      160 Baud                      Level:  TTL
Refresh Rate:   1.25 Seconds                    Modes: Normal, 10K, 3.9K, Shorted
Stream size:    20 Bytes 
Byte Data Name Description
1 MW2 Mode Word 2
2 PROMIDA PROM Identifier (low word)
3 PROMIDB PROM Identifier (high word)
4 ISSPMP IAC Present Motor Position
5 RAWADCT Coolant Temperature in a/d counts
6 FILTMPH Vehicle speed in MPH (1 mph/bit)
7 ADMAP  MAP Pressure variable: Range = 10.35 - 104.1 Kpa. 
Pressure in Kpa = (ADMAP+28.06)/2.71)
8 NTRPMX Engine Speed (rpm)/25
9 ADTHROT  Throttle Position Sensor  %TPS = ADTHROT / 2.56
10 INT  Integrator, Base Pulse (fuel) Correction 
128 = unity multiplier
11 ADO2A   Oxygen Sensor minor loop filtered value 
(4.42 mv/bit, 1.12V maximum)
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 ADDIW  A/D Discrete Input word
17 MCUIO  MCU input/output status byte
18 ADBAT  Battery voltage in A/D Counts
19 BLM  Block Learn Multiplier, Base Fuel correction 
(128 = Unity multiplier)
20 ALDLCNTR  ALDL rich/lean change counter.  Value expressed is number of crossovers.
 
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      Not Used 
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 pulses (engine not running)
MALFFLG2 MALF FLAG WORD 2 
Bit     Code    Description 
0       42      Electronic Spark Timing Monitor error 
1       41      Not Used 
3       35      IAC Error 
2       34      MAP Sensor Failed low 
4       33      MAP Sensor Failed High 
5       32      Not Used 
6       31      Not Used 
7       25      Not Used
MALFFLG3 MALF FLAG WORD 3 
Bit     Code    Description 
0       55      ADU Error 
1       54      Not Used 
2       53      Not Used 
3       52      Not used 
4       51      PROM error 
5       45      Oxygen sensor rich 
6       44      Oxygen sensor lean 
7       43      Not Used 
MCUIO  MCU input/output status word one 
Bit     Description                                Meaning if set: 
0       Idle Air Control Stepper coil A:        (Engaged) 
1       Idle Air Control Stepper coil B:        (Engaged) 
2       TCC (Automatic)                                (Converter On)
           Shift Light (Manual)                            (Light Lit)
3       COP2(Backup spark & Fuel)                Engaged 
4       Fan 
5       A/C clutch                                           (Solenoid On) 
6       IAC Stepper coil on/off                       Motor on 
7       Not Used
ADDIW A/D Discrete Inputs 
Bit     Description                                Meaning if set: 
0       Not Used 
1       Not Used 
2       Not Used 
3       Power Steering                              (Active)
4       Used For A/D DIAGLCL (Meaning unclear - drb)
5       Air Conditioning Disabled             (disabled) 
6       Crank                                            (engine Cranking) 
7       Park Neutral indicator                   (In Park/Neutral)
MW2
Mode Word 2
Bit    Description 
0       Road Speed pulse occurred (6.25 msec check)
1       Road Speed filter excercise flag
2       Reference Pulse occurred (6.25 msec check) 
3       Factory Test Mode (3.9 KOhms) 
4       Diagnostic Mode (0 Ohms) 
5       ALDL Mode (10 KOhms) 
6       High Battery Voltage: Disable MCU Solenoid 
7       Old Cell Flag (Air/Fuel)
MWAF
Air Fuel Mode Word 1
Bit    Description                               Meaning if set: 
0       Clear Flood Flag                       Cranked in clear flood mode 
1       Learn Control Enable flag          enable store 
2       Low Battery (IAC Inhibited)     Low Battery 
3      Hysteresis Flag for low RPM    Integrator Reset 
4       Asynchronous Pulse Flag           AP Flag 
5       First Time Closed Flag            First Time 
6       Rich/Lean Flag                        Rich 
7       Closed Loop Flag                    Closed Loop

 
Description of mode operation
Mode Data stream Timers Special Functions
20K words 1-20 normal Normal Operation
10K  words 1-20 expired
Bypasses Lean clamp for integrator
IAC Reset if RPM > 2K for the first time
Integrator reset criteria disabled
Burst Knock Retard Disabled
Bypass RPM and Temp Criteria for ESC Enable
Set Idle to 1000 RPM
3.9K words 1-20 expired backup spark and fuel control test mode
500 words 1-20 expired
Diagnostic display mode
(check engine lamp flashes with O2 sensor)
 
ALDL Connector PINOUT
Pin A - Ground Pin B - Diagnostics Enable (Resistance w.r.t. A)
Pin F - T.C.C. Pin C - Air Switch Solenoid
  Pin E - Serial Data Line TTL
  Pin G - Fuel Pump Prime