ALDL Description information
for these platforms:
3.0 Litre Buick Port
Fuel Injection System (1985 - 1986)
3.8 Litre Buick Port
Fuel Injection System (1984 - 1986) |
160 Baud ALDL operating characteristics:
Data Rate:
160 Baud
Level: TTL
Refresh Rate: 1.25 Seconds
Modes: 20K, 10K, 3.9 K, 500 Ohm
Stream size: 20 Bytes
in 1984 & 1985
25 Bytes in 1986 |
| Byte |
Name |
Description |
| 1 |
MW2 |
Mode Word 2 |
| 2 |
PROMIDA |
Prom Identifier (MSB) |
| 3 |
PROMIDB |
PROM Identifier (LSB) |
| 4 |
ISPMP |
IAC present motor position |
| 5 |
COOLDEGA |
Coolant Temperature, A/D Counts |
| 6 |
FILTMPH |
Vehicle speen in MPH |
| 7 |
LV8 |
Filtered calculated load variable |
| 8 |
NTRPMX |
Engine RPM (25 RPM/Bit) |
| 9 |
ADTHROT |
Throttle position sensor (A/D Counts) |
| 10 |
CORRCL |
Base pulse (fuel) closed loop operation |
| 11 |
ADO2AF |
Oxygen sensor minor loop filtered value |
| 12 |
MALFFLG1 |
Malfunction word 1 |
| 13 |
MALFFLG2 |
Malfunction word 2 |
| 14 |
MALFFLG3 |
Malfunction word 3 |
| 15 |
MWFA1 |
Mode Word (fuel/air) |
| 16 |
AIRFLOW |
Unlimited mass air flow value |
| 17 |
MCUINST |
MCU Status word |
| 18 |
OLDPA3 |
Electronic spark control (knock) counter input |
| 19 |
BLM |
Block Learn Multiplier, Base pulse fuel correction |
| 20 |
ALDLCNTR |
Oxygen sensor transition counter |
Remaining 1986 ALDL Byte descriptions
for 10Kohm Mode
| Byte |
Name |
Description |
| 21 |
SAP+1 |
Spark Advance (with respect to TDC) |
| 22 |
EGRDC |
EGR Duty cycle |
| 23 |
ATPSCNT |
Air Temperature Sensor (A/D Counts) |
| 24 |
BPW |
Base Pulse Width MSB |
| 25 |
BPW+1 |
Base Pulse Width LSB |
Remaining 1986 ALDL Byte descriptions
for 20K, 3.9K, and 500 ohm Mode
| Byte |
Name |
Description |
| 21 |
NOCKRTD |
Degrees retard due to knock |
| 22 |
ATPSCNT |
Air temperature sensor |
| 23 |
ADBAT |
Battery voltage/ A.D Count |
| 24 |
NOMALFCNT |
No malfunction count |
| 25 |
EGRDC |
EGR duty cycle |
|
Description of mode
operation (20 & 25 byte systems)
| Mode |
Data stream |
Timers |
Special Functions |
| 20K |
words 1-20, 1-25 |
normal |
Normal Operation |
| 10K |
words 1-20,
1-25 |
expired |
 |
Bypasses lean clamp for integrator |
|
IAC reset if RPM>2K for first time |
|
Burst knock retard disabled |
|
Add calibrated amt of spark to calibration |
|
Inhibit cannister purge |
|
Set idle to 1000 RPM |
|
| 3.9K |
words 1-20,
1-25 |
expired |
backup spark and fuel control test mode |
| 500 |
words 1-20,
1-25 |
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 D - Serial Data Line (TTL) |
| |
Pin G - Fuel Pump Prime |
|
NOTES:
The 1984 vehicles put eight
bytes of information on the ALDL data stream when in normal (20K) mode.
The words placed on the stream are:
 | 1- MW2 |
| 2- Accumulated Fuel (3.91
msec usec. per bit) |
| 3- Accumulated Fuel (15.3
usec. per bit) LSB |
| 4- Distance .0005
Miles per bit |
| 5- Vehicle speed in MPH |
| 6- Airflow (sec. / gram) |
| 7- RPM (25 / bit) |
| 8- Spark advance (90/256
degrees per bit) |
ALDL Mode does the following:
| Bypasses closed loop timers |
| Adds spark to spark calculation |
| Inhibits cannister purge |
| Controls engine idle speed to
1000 RPM |
| Inserts raw coolant count into
COOLDEGA |
| Bypasses fast idle cam, EGR/PARK
restriction, and burst knock routine |
| Engages ESC and toggles a bit
when ESC is energized |
| Increments ALDLCNTR on every
O2 sensor transition |
| Expires TCC timer |
|
BCD Word descriptions - Discrete
Data Information
| Name |
Word Description |
| MW2 |
Minor Loop Mode Word 2
Bit Description
0 Road speed pulse occurred (6.25 msec
check)
1 ESC Failure
2 Reference pulse occurred
3 Factory test (3.9 K ohm) mode
4 Diagnostic (500 Ohm) mode
5 ALDL (10K Ohm) mode
6 High battery voltage - Disable MCU
solenoid
7 Air meter pulse occurred (6.25 msec
check) |
| MWFA1 |
Fuel/Air Mode Word 1
Bit Description
0 Clear flood flag (1 = cranked in clear flood mode)
1 Learn Control enable flag (1 = enable store) (Tagged
for unknown reason- drb)
2 Low Battery (Tagged for unknown reason-
drb)
3 Proportional step taken flag (1 = rich,
0 = lean)
4 Highway fuel mode (1 = yes)(Tagged
for unknown reason- drb)
5 First time closed loop flag
6 Rich/Lean flag
7 Closed loop flag (1 = closed loop) |
| MCUINST |
MCU Instruction Word
Bit Description
0 Park/Neutral flag (1 = Park/neutral)
1 In cruise or A/C head pressure not high enough
3 Excessive power steering pressure(Tagged
for unknown reason- drb)
4 Cruise control enabled(Tagged
for unknown reason- drb)
5 Third Gear switch closed
6 Fourth Gear switch
closed
7 A/C Requested |
| NONVRAM |
Non-Volatile Mode Word [Cannot find where
it fits in this structure - drb]
Bit Description
0 O2 Sensor ready Flag
(1 = ready)
1 Not Used
2 Not Used
3 Improper Shutdown
flag (0 = proper, 1 = improper)
4 Not Used
5 Not Used
6 IAC Motor reset
(1 = enable)
7 Malfunction 42
flag (EST Monitor) |
| MALFFLG1 |
Malfunction Flag 1
Bit Code Description
0 24 Vehicle Speed
Sensor
1 23 Air Temperature
Sensor failed low (1984 models only)
2 22 Throttle Position
Sensor shorted
3 21 Throttle Position
Sensor open
4 15 Coolant Temperature
sensor failed low
5 14 Coolant temperature
sensor failed high
6 13 Oxygen sensor
failed
7 12 No reference pulses |
| MALFFLG2 |
Malfunction Flag 2
Bit Code Description
0 42 Electronic spark
timing monitor error
1 41 CAM sensor fialure
2 35 Not Used
3 34 Mass airflow sensor
failed low
4 33 Mass airflow sensor
failed high
5 32 EGR failure
6 31 Wastegate pulses
not detected
7 25 Air temperature
sensor failed high |
| MALFFLG3 |
Malfunction Flag 3
Bit Code Description
0 55 ADU eror
1 54 Not Used
2 53 Water injection
failure
3 52 CAL pack missing
4 51 PROM error
5 45 Oxygen sensor
failed rich
6 44 Oxygen sensor
failed lean
7 43 ESC failure |
|