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13 Open Oxygen Sensor Circuit
14 Coolant Sensor Circuit Shorted
15 Coolant Sensor Circuit Open
16 Vehicle Speed Sensor Buffer Fault
21 Throttle Position Sensor (Signal Voltage High)
22 Throttle Position Sensor (Signal Voltage Low)
24 Vehicle Speed Sensor (VSS) Circuit
25 IAT Sensor (MAT) Shorted
28 Transmission Range (TR) Pressure Switch Assembly Fault
32 Exhaust Gas Recirculation System
33 Manifold Absolute Pressure Sensor (MAP) Voltage High)
34 Manifold Absolute Pressure Sensor (MAP) Voltage Low)
35 Idle Air Control (IAC) System
37 Brake Switch Stuck "On"
38 Brake Switch Stuck "Off"
41 1X Signal Error
42 Ignition Control Circuit
43 Knock Sensor (KS) Circuit
44 Oxygen Sensor Circuit Lean Exhaust Indicated
45 Oxygen Sensor Circuit Rich Exhaust Indicated
51 Faulty Mem-Cal or PROM Problem
52 System Voltage High Long
53 System Voltage High
54 Fuel Pump Relay
55 PCM
58 Transmission Temperature Sensor Circuit (Low Temp)
59 Transmission Temperature Sensor Circuit (High Temp)
66 3-2 Control Solenoid Circuit Fault
67 Torque Converter Clutch Solenoid Circuit Fault
69 TCC Stuck "On"
72 Vehicle Speed Sensor (VSS) Circuit
73 Pressure Control Solenoid Error
75 System Voltage Low
79 Transmission Fluid - Over Temperature
81 2-3 Shift Solenoid Circuit Fault
82 1-2 Shift Solenoid Circuit Fault
83 TCC Pulse Width Modulated (PWM) Solenoid Circuit Fault

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.

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