Diagnostic Trouble Codes - 1991
Buick
| 13 | Open Oxygen Sensor Circuit |
| 14 | Coolant Temperature Sensor (High Temp Indicated) |
| 15 | Coolant Temperature Sensor (Low Temp Indicated) |
| 16 | System Voltage High |
| 17 | RPM Signal Problem |
| 21 | Throttle Position Sensor (Signal Voltage High) |
| 22 | Throttle Position Sensor (Signal Voltage Low) |
| 23 | Manifold Air Temperature (MAT) Circuit (Low Sig.) |
| 24 | Vehicle Speed Sensor (VSS) Circuit |
| 25 | Manifold Air Temperature (MAT) High Temp Indicated |
| 26 | Quad-Driver (QDM) Circuit |
| 31 | Park/Neutral Switch Circuit |
| 34 | Mass Air Flow Sensor (MAF) (GM/SEC Low) |
| 36 | Transaxle Shift Control Problem |
| 38 | Brake Input Circuit |
| 39 | Torque Converter Clutch (TCC) Circuit |
| 42 | Electronic Spark Timing (EST) Circuit |
| 43 | Electronic Spark Control (ESC) Circuit |
| 44 | Oxygen Sensor Circuit (Lean Exhaust Indicated) |
| 45 | Oxygen Sensor Circuit (Rich Exhaust Indicated) |
| 46 | Power Steering Pressure Switch (PSPS) Circuit |
| 48 | Misfire Diagnosis |
| 51 | Mem-Cal Error |
| 58 | Personal Automotive Security System Circuit. |
| 61 | Cruise Vent Solenoid Circuit. |
| 62 | Cruise Vacuum Solenoid Circuit. |
| 65 | Cruise Servo Position Circuit. |
| 66 | Low A/C Refrigerant Charge. |
| 67 | Cruise Switches Circuit. |
| 68 | Cruise System Problem. |
| 69 | A/C Head Pressure Switch Circuit. |
To extract a trouble from the computer for diagnostic purposes, the Assembly Line Communication Link (ALDL) connector is used.
Ground terminals A and B with the ignition "ON" and engine not running. The system will enter the diagnostic mode. In this mode, the computer will display a 12, three consecutive times, by flashing the "CHECK ENGINE", "SERVICE ENGINE SOON" or "MALFUNCTION INDICATOR LAMP" or light. A 12 consists of one flash, a short pause, then two flashes in rapid succession.
After 12 is displayed, any stored trouble s will be displayed by flashing the "CHECK ENGINE", "SERVICE ENGINE SOON" or "MALFUNCTION INDICATOR LAMP" light. All s are displayed 3 times each then a 12 will repeat. In the diagnostic mode, the computer will also energize all computer controlled relays and solenoids.
ALDL Connector (Located Underdash)
The ALDL diagnostic connector is located in the passenger compartment.
