Navigating the complexities of vehicle diagnostics can be daunting, especially when dealing with classic models like the 1993 Jeep Cherokee. While the term “OBD2” technically became mandatory in 1996, understanding the diagnostic systems around that era, including the crucial wiring, is essential for effective troubleshooting. This guide, tailored for your 1993 Jeep Cherokee, provides a comprehensive list of diagnostic trouble codes to help you decipher your vehicle’s signals and address potential issues.
Diagnostic Trouble Codes for Carbureted Engines
These codes are relevant for earlier models of the 1993 Jeep Cherokee that may feature carbureted engines. Note that these systems are pre-OBD2 and use a simpler diagnostic approach.
- CODE 12: No distributor reference pulses to the ECM. This is a real-time code, not stored in memory, and expected when the ignition is on but the engine is off.
- CODE 13: Oxygen sensor circuit malfunction. This code sets after approximately 5 minutes of part-throttle operation under load.
- CODE 14: Coolant sensor circuit shorted. Requires about 5 minutes of engine operation to trigger.
- CODE 15: Coolant sensor circuit open. Similar to Code 14, it needs 5 minutes of engine run time.
- CODE 21: Throttle position sensor circuit issue. Sets after 25 seconds at curb idle speed.
- CODE 23: Mixture control solenoid circuit problem (shorted or open).
- CODE 34: Vacuum sensor circuit malfunction. Requires 5 minutes at curb idle speed.
- CODE 41: No distributor reference pulses to the ECM at specified manifold vacuum. This code is stored in memory for later retrieval.
- CODE 42: Electronic Spark Timing (EST) bypass or EST circuit fault (short to ground or open).
- CODE 44: Lean exhaust indication. Sets after 5 minutes in closed loop at part throttle.
- CODE 44 & 45 (simultaneous): Indicates a likely problem within the oxygen sensor circuit itself.
- CODE 45: Rich exhaust indication. Similar conditions to Code 44 for setting.
- CODE 51: Faulty calibration unit (PROM) or incorrect installation. Takes up to 30 seconds to set.
- CODE 54: Mixture Control (MC) solenoid circuit shorted or potentially a faulty ECM.
- CODE 55: Voltage reference shorted to ground (terminal 21), faulty oxygen sensor, or faulty ECM.
Diagnostic Trouble Codes for Fuel Injected Engines (Pre-1991 Models)
While less likely on a 1993 model, some early fuel-injected Cherokees utilized these specific codes.
- Code 1000-1073 & 1200-1223: This range covers a broad spectrum of potential issues within the fuel injection system and related sensors. These codes are highly specific and pinpoint problems such as:
- Ignition line voltage issues (1000, 1001)
- Oxygen heater circuit (1002)
- Battery voltage problems (1004)
- Sensor ground faults (1005)
- Diagnostic enable line issues (1010, 1011)
- MAP sensor circuit problems (1012, 1013, 1052, 1053, 1222)
- Fuel pump circuit faults (1014, 1015, 1282)
- Charge air temperature sensor issues (1016, 1017)
- ECU communication problems (1018, 1024, 1028, 1047, 1048, 1049, 1200, 1223)
- Engine starting problems (1021)
- Start line faults (1022, 1024)
- Throttle position sensor and idle issues (1025, 1027, 1031, 1032, 1037, 1050, 1051, 1294, 1297)
- Park/Neutral switch (1038, 1899)
- Latched B+ voltage problems (1040, 1041, 1042, 1218)
- Coolant temperature sensor faults (1054, 1055, 1056)
- Knock sensor circuit issues (1057, 1058)
- A/C system related faults (1059, 1060, 1061, 1062, 1063, 1064, 1070, 1071, 0645)
- Oxygen sensor readings (1065, 1066)
- Latch relay circuit issues (1067, 1068)
- Speed sensor signal problems (1073, 0500)
- Injector faults (1202, 1209, 1221, 0201-0208)
- EGR solenoid voltage issue (1220)
Diagnostic Trouble Codes for 1991-1995 Models (Including 1993)
These codes are the most relevant for your 1993 Jeep Cherokee, representing the diagnostic system in place for these model years.
- Code 11: Camshaft or Ignition signal – no reference signal during cranking.
- Code 12: Memory to controller cleared recently (within 50-100 starts). This can be normal after battery disconnection.
- Code 13: MAP sensor pneumatic signal – no variation detected or incorrect barometric pressure reading.
- Code 14: MAP voltage too high or too low.
- Code 15: Vehicle speed sensor signal – no signal during road load.
- Code 16: Knock sensor circuit – open or short detected. Also, Battery input sensor – voltage below 4V running.
- Code 17: Low engine temperature – coolant temperature remains low, possibly thermostat issue.
- Code 21: Oxygen sensor signal – neither rich nor lean condition detected.
- Code 22: Coolant voltage low or high – sensor input out of acceptable range.
- Code 23: Air Charge or Throttle Body temperature voltage HIGH/LOW – sensor input out of range.
- Code 24: Throttle Position sensor voltage high or low.
- Code 25: Automatic Idle Speed (AIS) motor driver circuit – short or open in control circuits.
- Code 26: Injectors No. 1, 2, or 3 peak current not reached, high resistance.
- Code 27: Injector control circuit – bank output driver issue. Also, Injectors No. 1, 2, or 3 control/peak current problem.
- Code 31: Purge solenoid circuit – open or short.
- Code 32: Exhaust Gas Recirculation (EGR) solenoid circuit – open or short, or EGR system failure.
- Code 33: Air conditioner clutch relay circuit – open or short (ignore if no A/C).
- Code 34: Speed control servo solenoids or MUX speed control circuit HIGH/LOW – open/short in vacuum/vent solenoids or speed control switch issue.
- Code 35: Radiator fan control relay circuit – open or short. Also, Idle switch shorted (some 1993 models).
- Code 37: Part Throttle Unlock (PTU) circuit for torque converter clutch – open or short. Also, Baro Reed Solenoid issue, Shift indicator circuit (manual transaxle).
- Code 41: Charging system circuit – generator field driver issue.
- Code 42: Fuel pump or no Autoshut-down (ASD) relay voltage sense at controller.
- Code 43: Ignition control circuit – peak primary current issue. Also, Ignition coil #1, 2, or 3 primary circuit problem.
- Code 44: Battery temperature voltage problem, or Engine coolant temperature circuit fault. Also, Fused J2 circuit missing (signal engine module), Overdrive solenoid circuit issue.
- Code 46: Battery voltage too high – charging voltage too high.
- Code 47: Battery voltage too low – charging voltage too low.
- Code 51: Air/fuel at limit – oxygen sensor indicates LEAN condition.
- Code 52: Air/fuel at limit – oxygen sensor indicates RICH condition.
- Code 53: Internal controller failure – internal engine controller fault.
- Code 54: Camshaft or (distributor sync.) reference circuit – No camshaft position sensor signal.
- Code 55: End of message – end of diagnostic code output.
- Code 61: Baro read solenoid – open or short.
- Code 62: EMR mileage not stored – EEPROM update failure.
- Code 63: EEPROM write denied – EEPROM write attempt unsuccessful.
- Code 64: Flex fuel sensor – out of range (1993 CNG). CNG Temperature/Pressure out of range.
- Code 66: No CCD messages or no BODY/EATX CCD messages – CCD bus communication failure.
- Code 76: Ballast bypass relay – open or short in fuel pump relay circuit.
- Code 77: Speed control relay – open or short detected.
- Code 88: Display used for start of test – indicates diagnostic test initiation.
- Code Error: Fault code error – Unrecognized fault ID received by DRBII diagnostic tool.
Alt text: Thumbs up icon symbolizing helpful Jeep Cherokee diagnostic information, relevant to OBD2 port and wiring discussions.
Diagnostic Trouble Codes for 1996 and Later Models (OBD2 – P Codes)
While your 1993 Cherokee predates mandatory OBD2, understanding these common P-codes is helpful for general automotive diagnostic knowledge and in case of any system upgrades or modifications your vehicle might have received.
- P0107-P0108: Manifold Absolute Pressure/Barometric Pressure Circuit Low/High Input
- P0112-P0113: Intake Air Temperature Circuit Low/High Input
- P0117-P0118: Engine Coolant Temperature Circuit Low/High Input
- P0121-P0123: Throttle/Pedal Position Sensor/Switch A Circuit Range/Performance Problem, Low/High Input
- P0125: Insufficient Coolant Temperature for Closed Loop Fuel Control
- P0129, P1195, P1197: Catalyst Monitor Slow O2 Sensor (Bank 1 Sensor 1 & 2, Bank no. 1 Sensor no. 2)
- P0131-P0141: Left Bank Upstream/Downstream O2 Sensor Voltage Shorted to Ground/Voltage, Slow Response, Heater Malfunction
- P0152: Left Upstream O2 Sensor Slow Response
- P0162: Charging System Voltage Too Low
- P0171-P0172: Fuel System Too Lean/Too Rich (Right Rear/Left Bank)
- P0201-P0208: Injector Control Circuit Malfunction (Cylinders 1-8)
- P0300-P0308: Random/Multiple Cylinder Misfire Detected, Cylinder Specific Misfire (Cylinders 1-8)
- P0320, P0340: No Crank Reference Signal PCM, No Cam Signal at PCM
- P0351: Ignition Coil No. 1 Primary Circuit
- P0420: Catalytic Converter Efficiency Failure (Bank 1)
- P0441-P0455: Evaporative Purge Flow Monitor Failure, EVAP Leak Detected (Small, Gross Leak), Evap Purge Solenoid Circuit
- P0460-P0463: Fuel Level Unit No Change, Voltage Too Low/High
- P0505: Idle Air Control Motor Circuits
- P0600-P0601: PCM/Serial Communication Link Malfunction, Internal Controller Failure
- P0622: Generator Field Not Switching Properly
- P0711-P0713: Transmission Fluid Temperature Sensor, No Temperature Rise/Voltage Too Low/High
- P0720: Low Output Speed Sensor RPM Above 15 MPH
- P0740-P0743: Torque Converter Clutch, No RPM Drop at Lockup, Solenoid/Trans Relay Circuits
- P0748, P0751, P0753: Governor Pressure Solenoid Control/Trans Relay Circuits, Overdrive Switch Pressed, Trans 3-4 Shift Solenoid/Trans Relay Circuits
- P0783: 3-4 Shift Solenoid, No RPM Drop @ 3-4 Shift
- P1281-P1282: Engine is Cold Too Long, Fuel Pump Relay Control Circuit
- P1296-P1297: No 5 Volts to MAP Sensor, No Change in MAP from Start to Run
- P1388-P1389: Auto Shutdown Relay Control Circuit, No ASD Relay Output Voltage at PCM
- P1391-P1398: Intermittent Loss of CMP or CKP, Misfire Adaptive Numerator at Limit/No Crank Sensor Learn
- P1486-P1495: EVAP Leak Monitor Pinched Hose/Obstruction, Battery Temp Sensor Voltage Too High/Low, Leak Detection Pump Pressure Switch/Solenoid Circuit
- P1594-P1597: Charging System Voltage Too High, Speed Control Solenoid Circuits, Switch Always High/Low
- P1683, P1696, P1698: Speed Control Power Circuit, PCM Failure EEPROM Write Denied
- P1756-P1765: Governor Pressure Not Equal to Target, Above 3 PSI in Gear, Sensor Offset/Volts Too Low/High, Trans 12 Volts Supply Relay Control Circuit
Understanding Your 1993 Jeep Cherokee’s Diagnostic System
While this list provides a solid foundation for understanding diagnostic codes for your 1993 Jeep Cherokee, remember that accurate diagnosis often requires a deeper dive into the specific wiring diagrams relevant to your model year and engine type. The OBD2 port, even in these transitional years, serves as a crucial access point for retrieving these codes and beginning your troubleshooting process. Always consult a repair manual specific to your 1993 Jeep Cherokee for detailed wiring diagrams and diagnostic procedures to ensure accurate repairs.
