Diagnostic Trouble Codes - 1991
Cadillac
| E12 | No Distributor Reference Signal |
| E13 | Oxygen Sensor Not Ready |
| E14 | Shorted Coolant Sensor |
| E15 | Open Coolant Sensor |
| E16 | Generator Voltage Out of Range |
| E19 | Shorted Fuel Pump Circuit |
| E20 | Open Fuel Pump Circuit |
| E21 | Shorted Throttle Position Sensor |
| E22 | Open Throttle Position Sensor |
| E23 | EST Signal Problem |
| E24 | Speed Sensor Circuit Problem |
| E26 | Shorted Throttle Switch Signal |
| E27 | Open Throttle Switch Signal |
| E30 | ISC RPM Out Of Range |
| E31 | Shorted MAP Sensor Signal |
| E32 | Open MAP Sensor Signal |
| E34 | MAP Sensor Signal Out Of Range |
| E37 | Shorted MAT Sensor Signal |
| E38 | Open MAT Sensor Signal |
| E39 | VCC Engagement Problem |
| E40 | Power Steering Pressure Switch Signal |
| E44 | Oxygen Sensor Signal Lean |
| E45 | Oxygen Sensor Signal Rich |
| E47 | BCM to PCM/ECM Data Problem |
| E48 | EGR System Problem |
| E52 | PCM/ECM Memory Reset |
| E53 | Distributor Signal Interrupt |
| E55 | TPS Misadjusted |
| E58 | Pass Key Control Problem |
| E60 | Cruise - Not In Drive |
| E61 | Cruise - Vent Solenoid Problem |
| E62 | Cruise - Vacuum Solenoid Problem |
| E63 | Cruise - Set Speed vs Vehicle Speed |
| E64 | Cruise - Acceleration Too High |
| E65 | Cruise - Servo Position Signal Problem |
| E66 | Cruise - Engine RPM Too High |
| E67 | Cruise - Switch Shorted |
| E68 | Cruise - Command Problem |
| E70 | Intermittent TPS |
| E71 | Intermittent MAP |
| E73 | Intermittent Coolant Sensor |
| E74 | Intermittent MAT Sensor Signal |
| E75 | Intermittent VSS Signal |
| E80 | Fuel System Rich |
| E85 | Throttle Body Service Required |
| E90 | Cruise - VCC Brake Switch Signal Problem |
| E91 | Cruise - PRNDL Switch Problem |
| E92 | Heated Windshield Request Problem |
| E96 | Torque Converter Overstress |
| E97 | P/N To D/R Engagement Problem |
| E98 | P/N To D/R ISC Engaged Problem |
| E99 | Cruise - Servo Apply Problem |
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.
