Deciphering the mystery behind your Chrysler’s check engine light can feel daunting, but understanding the fault codes is the first step to diagnosing and resolving issues. While modern Chrysler vehicles utilize the standardized OBD2 (On-Board Diagnostics II) system, older models, sometimes referred to as OBD1, employ a different retrieval method. This guide will help you understand how to access and interpret these diagnostic trouble codes, focusing on the principles relevant to Chrysler vehicles.
One method to retrieve fault codes on some older Chrysler models involves using the Malfunction Indicator Lamp (MIL), commonly known as the Check Engine light. This process, accessible through a specific ignition switch action, allows you to read out codes as flashes from the dashboard indicator.
Accessing Diagnostic Codes via Key Cycling
For certain Chrysler vehicles, you can initiate the self-diagnostic mode and read OBD1-style codes by using a specific key cycling technique. This involves turning the ignition key between the ‘ON’ and ‘OFF’ positions in a particular sequence.
Here’s how to attempt retrieving these codes:
- Start in the ‘ON’ position: Ensure your ignition switch is in the ‘ON’ position.
- Cycle to ‘OFF’ and back ‘ON’: Turn the ignition switch from ‘ON’ to ‘OFF’ and then back to ‘ON’.
- Repeat the cycle: Do this ‘ON-OFF-ON’ cycle three times in total, completing the sequence in less than 5 seconds and ending in the ‘ON’ position.
If successful, the Check Engine light will begin to flash, indicating the stored fault codes.
Interpreting the Flash Codes
The fault codes are communicated through a series of flashes. These flashes are differentiated by their duration:
- Long flashes: Represent the ‘Tens’ digit of the code.
- Short flashes: Represent the ‘Units’ digit of the code.
For example, if you see two long flashes followed by one short flash, this indicates code 21. The codes are displayed sequentially, and the sequence is typically repeated. Code 55, indicated by five short flashes followed by five short flashes, usually signifies the end of the diagnostic code output.
Common Chrysler OBD1 Style Fault Codes
While these codes are from an older system and not strictly OBD2, understanding them can still provide valuable insights into potential issues, especially if you are working on a classic or older Chrysler vehicle. Here is a list of common codes and their descriptions, similar to those found in older Chrysler diagnostic systems:
| Code | Description |
|---|---|
| 11 | No Crank Reference Signal at PCM |
| 12 | Battery Disconnected within Last 50 Key-on Cycles |
| 13 | MAP Sensor Pneumatic Problem |
| 14 | MAP Sensor Voltage Too High or Too Low |
| 15 | No Vehicle Speed Sensor Signal |
| 16 | Battery Voltage Sensor Out of Range or Knock Sensor Circuit Fault |
| 17 | Engine Not Reaching Operating Temperature |
| 21 | Oxygen Sensor Signal No Change During Test |
| 22 | Coolant Temperature Sensor Voltage Too High or Too Low |
| 23 | Intake Air Temperature Sensor Voltage Too High or Too Low |
| 24 | Throttle Position Sensor Voltage Too High or Too Low |
| 25 | Idle Air Control Valve Problem |
| 26 | Injector Peak Current Not Reached |
| 27 | Injector Circuit Problem – Driver Side |
| 31 | Purge Solenoid Circuit Problem |
| 32 | EGR Valve Solenoid Circuit Problem |
| 33 | A/C Relay Circuit Problem |
| 34 | Speed Control Vacuum Solenoid Circuits Problem |
| 35 | Radiator Fan Relay Circuit Problem |
| 36 | Turbo Wastegate Solenoid Circuit Problem |
| 37 | Torque Converter Clutch Solenoid Circuit Problem |
| 41 | Alternator Field Control Circuit Problem |
| 42 | Auto Shutdown Relay Control Circuit Problem |
| 43 | Ignition Coil Driver Circuit Problem |
| 44 | Battery Temperature Sensor Voltage Too High or Too Low |
| 45 | |
| 46 | Battery Voltage Too High |
| 47 | Battery Voltage Too Low |
| 51 | Mixture Lean |
| 52 | Mixture Rich |
| 53 | Internal Controller Failure – SCM Failure |
| 54 | Camshaft Sensor Signal Intermittent |
| 55 | End of Message |
| 56 | |
| 57 | |
| 61 | Barometric Pressure Sensor Solenoid Circuit Problem |
Important Note: This key cycling method and the associated codes are typical of older Chrysler systems and may not apply to all models, especially newer OBD2 compliant vehicles. Modern vehicles require an OBD2 scanner to accurately retrieve fault codes.
Moving Towards OBD2 and Modern Diagnostics
The OBD2 system became standard in vehicles in the mid-1990s and provides a more comprehensive and standardized approach to vehicle diagnostics. OBD2 scanners plug into a diagnostic port in your vehicle and provide fault codes in a digital format, along with more detailed information and live data.
For any Chrysler vehicle manufactured in or after 1996, and likely many before that, you will need to use an OBD2 scanner to read the diagnostic trouble codes. These scanners are readily available and are an essential tool for modern car maintenance and repair.
Conclusion
While understanding older diagnostic methods like key cycling can be helpful, especially for vintage Chrysler vehicles, remember that modern Chrysler vehicles rely on the OBD2 system. When your check engine light illuminates, the most effective way to diagnose the issue is by using an OBD2 scanner to retrieve the specific fault codes. This will provide a clearer understanding of the problem and guide you towards the necessary repairs, ensuring your Chrysler runs smoothly and efficiently. Always consult a qualified mechanic for diagnosis and repairs if you are unsure or uncomfortable working on your vehicle yourself.
