In this page we will explain how to retreive the trouble codes stored in the engine control computer in Dodge, Chrysler and Plymouth vehicles prior to OBD II.
 
The self diagnosis information contained in the SBEC or SMEC ( computer ) can be accessed either by the ignition key or by using a scan tool, the scan tool needs to be plugged in to the diagnostic connector in the engine compartment to read the codes and parameters on the digital display screen. 

We will focus on the alternate method using the ignition switch since most people don't have a scan tool.

To obtain the codes using the ignition key method, first set the parking brake and place the vehicle in Park if is automatic or in neutral if it has a manual transaxle.
Raise the engine speed to a[[roximately 2500 RPM's and slowly let the speed down to idle. Cycle the air conditioning system on then off. If the vehicle has an automatic transmission, with your foot on the brake, select each position on the transmission ( Reverse, drive, low etc. ) and bring the shifter back to Park. This will allow the computer to obtain any fault codes that might be linked to any of the sensors controlled by the transmission, engine speed or AC system.

To display the codes on the dashboard through the check engine light, turn the ignition key On, Off, On, Off and finally On without starting the vehicle. The codes will begin to flash, the check engine light will blink the number of the first digit then pause and blink the number of the second digit, for example:
 For code 23 ( throttle body temperature sensor circuit ) the check engine light will flash twice, there will be a pause followed by 3 flashes.
 
Take note that certain criteria must be met for a fault code to be entered into the engine controller memory. The criteria can be a specific range of engine RPM, engine temperature or input voltage to the engine controller. It is possible that a fault code for a particular monitored circuit may not be entered into the memory despite the malfunction. This may happen because the fault code criteria hasn't been met, for example:
 The engine must be operating between 750 and 2000 RPM in order to monitor the MAP sensor circuit correctly. If the engine speed is raised above 2400 RPM, the MAP sensor output circuit shorts to ground and will not allow a fault code to be entered into the memory.
 The opposite can also occur: A trouble code can be entered into the memory that suggests a malfunction within another component that is not monitored by the computer, for example:
 A fuel pressure problem cannot register a fault code directly but instead it will cause a rich/lean fuel mixture problem. Causing an oxygen sensor malfunction code stored in the computer. Be aware of the interrelationship of the sensors and circuits and the overall relationship of the emissions control and fuel injection systems.

 Clearing the codes:
  The codes can be cleared by disconnecting the negative battery cable for at least 15 seconds, on OBD II models the codes can only be cleared with a scan tool.

CODE          PROBABLE CAUSE

 11   No distributor reference signal during engine cranking
 12   Battery pwer to compute disconnected in last 50 to 100 cycles; memory standby power lost ( 1983-1990 )
 13   Manifold absolute pressure ( MAP ) sensor vacuum circuit slow or no change in MAP sensor input or output
 14   Manifold absolute pressure sensor electrical circuit high or low voltage
 15   Vehicle speed sensor circuit
 16   Loss of battery voltage ( 1983-1989 )
 17   Knock sensor circuit open or shorted during engine operation  ( 1985 and 1986 turbo models )
 17   Engine running too cold
 21   Oxygen sensor circuit voltage in neutral zone or above normal range  
 22   Coolant temperature sensor unit high or low voltage
 23   Throttle body air temperature sensor circuit high or low voltage ( 1987-1990 TBI models )
 23   Intake air temperature sensor circuit high or low voltage ( 1991-1998 )
 24   Throttle position sensor circuit high or low voltage
 25   Idle speed control ( ISC ) or idle air control ( IAC ) motor driver circuit shorted
 25   Automatic idle speed ( AIS ) motor driver circuit shorted
 26   Peak injector driver current not reached because of high resistance in circuit
 27   Injector driver not responding correctly to injector control signal
 31   Canister purge solenoid circuit open or shorted
 32   Exhaust Gas Recirculation ( EGR ) transducer solenoid circuit open or shorted, or EGR system failed to respond
        to command ( 1987-1994 )
 32   Malfunction indicator lamp ( MIL ) circuit open or shorted ( 1983-1986 )
 33   Air conditioning clutch relay circuit open or shorted
 34   Spare driver circuit open or shorted ( 1985 models )
 34   Open or shorted circuit at the EGR solenoid ( 1983-1985 )
 34   Speed control vacuum or vent solenoid circuit open or shorted
 35   Cooling fan relay circuit open or shorted
 35   Idle switch circuit open or shorted ( 1988-1994 RWD models )
 36   Spare driver circuit open or shorted
 36   Turbocharger wastegate solenoid circuit open or shorted
 37   Shift indicator lamp circuit open or shorted ( 1985 and 1986 models with manual transmission )
 37   Part throttle unlock solenoid driver circuit open or shorted ( 1985 and 1986 models with automatic transmission )
 37   Baro solenoid circuit open or shorted ( turbo models )
 41   Charging system excess or lack of field current
 42   Automatic shutdown driver ( ASD ) relay circuit open or shorted
 43   Ignition coil control circuit or spark interface circuit  output stage not responding to control command
 44   Fault in computer ( 1983 and 1984 models )
 44   Battery temperature signal out of range ( 1985-1987 and 1992-1994 3.3 L and 3.8 L )
 44   No fused circuit voltage at computer connector during engine operation ( 1987-1989 )
 45   Overboost shut off circuit on MAP sensor reading above overboost limit
 45   Overdrive solenoid circuit open or shorted  ( 1989-1994 RWD models )
 46   Charging system voltage too high
 47   Charging system voltage too low
 51   Oxygen sensor voltage indicates lean during engine operation
 52   Oxygen sensor voltage indicates rich during engine operation
 52   Fault present in computer ( 1983-1986 )
 53   Module internal problem; SMEC/SBEC failure; internal engine controller fault condition detected
 54   Problem with the distributor syncronization circuit, no sync pick-up signal detected during operation
 55   End of code output
 61   BARO solenoid circuit open or shorted ( 1989 turbo models )
 62   Emissions maintenance reminder light mileage is not being updated ( 1989 on )
 63   EEPROM write denied, controller failure ( 1989 on )
 64   Speed control vent solenoid no. 1 circuit open or shorted ( 1990 2.2 L turbo )
 64   Flexible fuel ( methanol ) sensor indicates concentration sensor input more than the acceptable voltage
 64   Flexible fuel ( methanol ) sensor indicates concentration sensor input less than the acceptable voltage
 65   Manifold tuning valve solenoid circuit open or shorted
 65   Power steering switch failure ( 1996 models )
 66   No message from the transmission control module ( TCM ) to the powertrain control module ( PCM )
 66   No message from the body control module ( BCM ) to the powertrain control module ( PCM )
 71   5 volt PCM output low
 72   Catalytic converter efficiency failure
 77   Speed control power relay circuit
 88   Start of test