1991 Cavalier CEL diagnostic

Asked by Feb 28, 2011 at 07:43 PM about the 1991 Chevrolet Cavalier

Question type: Maintenance & Repair

CEL is always on, and car will drive a few miles then die, how do I get the CEL into diagnostic mode? I know I will need to jumper something, and then count the flashes, but I don't know where or what to jumper. Also, is there a list of the codes on here somewhere?

1 Answer


Find the diagnostic connector below the dash and cross terminals A and B CODE 13 Indicates that the oxygen sensor circuit CODE 14 Sets if the sensor or signal line are Coolant Sensor (CTS) grounded for 3 seconds. CODE 15 Sets if the sensor, wires, or connections Coolant Sensor (CTS) are open for 3 seconds. LOW Temperature indication CODE 21 TPS voltage of more than 2.5 volts for Throttle Position Sensor (TPS) 3 seconds at an engine speed less than 1200 rpm. HIGH Voltage Signal CODE 22 A shorted to ground or open signal circuit Throttle Position Sensor (TPS) will set code in 3 seconds. LOW Voltage Signal CODE 23 Sets if the sensor, wires, or connections Manifold Air Temperature Sensor (MAT) are open for 3 seconds. or Intake Air Temperature (IAT) LOW Temperature indication CODE 24 No vehicle speed present during road Vehicle Speed Sensor (VSS) load deceleration. NO Vehicle Speed Indication CODE 25 Sets if the sensor or signal line are Manifold Air Temperature Sensor (MAT) grounded for 3 seconds. or Intake Air Temperature (IAT) HIGH Temperature indication CODE 32 Vacuum switch shorted to ground on start up Exhaust Gas Recirculation (EGR) OR Switch not closed after the ECM has commanded EGR for a specified period of time. OR EGR solenoid circuit open for a specified period of time. CODE 33 MAP sensor output too high for 5 seconds Manifold Absolute Pressure (MAP) or an open circuit. LOW Vacuum CODE 34 Low or no output from sensor with engine running. Manifold Absolute Pressure (MAP) HIGH Vacuum CODE 35 IAC error. Idle Air Control (IAC) CODE 42 ECM has seen an open or grounded EST or Bypass circuit. electronic Spark Timing (EST) CODE 43 Signal to the ECM has remained low for too long Electronic Spark Control (ESC) or the system has failed a functional check. CODE 44 If voltage to oxygen sensor remains BELOW .2v LEAN Exhaust Indication. for more than 20 seconds, code is set. CODE 45 If voltage to oxygen sensor remains ABOVE .7v RICH Exhaust Indication. for more than 1 minute, code is set. CODE 51 Faulty MEM-CAL, PROM, or ECM. CODE 52 Faulty or missing CAL-PACK. CODE 53 System overvoltage. Indication of a faulty alternator or regulator. Camaro/Firebird uses a Code 53 for Vehicle Anti-Theft System (VATS). CODE 54 Sets when the fuel pump voltage is less than LOW Voltage To Fuel Pump. 2 volts when reference pulses are being received. CODE 55 Faulty ECM.

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