Converting a 1995 Dodge from OBD1 to OBD2 can seem daunting, but it’s achievable with careful planning and execution. While commercially available conversion harnesses exist, creating a custom sub-harness offers a tailored solution. This guide outlines the key considerations and potential challenges involved in this conversion process.
Understanding the Conversion Process
A common approach to OBD1 to OBD2 conversion involves modifying the existing wiring harness. This typically includes replacing the OBD1 connector with an OBD2 connector and adding any necessary wiring for missing functionalities, like transmission controls. It’s often possible to de-pin the OBD1 connector and re-pin them into an OBD2 connector if the pin configurations are compatible.
Key Challenges and Considerations
While the basic wiring conversion may seem straightforward, several critical factors demand attention:
Injector Compatibility
Mopar vehicles often used different injector types with varying flow rates and connector styles throughout the years. Ensure that the chosen injectors match the OBD2 ECM’s requirements. Mismatched injectors can lead to performance issues or even engine damage. Injector conversion harnesses are often available to address connector discrepancies.
Cruise Control System
OBD1 and OBD2 systems employ different methods for controlling cruise control. OBD1 typically uses multiple pins on the ECM with distinct on/off and set/resume signals, while OBD2 often relies on fewer pins with variable voltage signals. A custom sub-harness may require incorporating resistors to adapt the cruise control switches to the OBD2 ECM’s signaling method.
Sourcing Components
Locating a male OBD2 connector that precisely fits the female OBD1 connector can prove challenging. Researching compatible connectors or exploring custom fabrication options may be necessary. Additionally, sourcing the correct wiring, pins, and resistors is crucial for a successful conversion.
Building a Custom Sub-Harness
Creating a custom sub-harness involves carefully mapping the pinouts of both the OBD1 and OBD2 systems. Identify the corresponding wires for essential functions like engine management, transmission control, and diagnostics. Add new wires for missing functionalities in the OBD1 system and integrate resistors or other components as needed for compatibility. Thorough testing and verification are paramount to ensure proper functionality and avoid potential problems.
Conclusion
Converting the OBD port on a 1995 Dodge to OBD2 requires a comprehensive understanding of both systems and meticulous attention to detail. Building a custom sub-harness offers a flexible solution, but addressing challenges like injector compatibility and cruise control signaling is essential. Careful planning, accurate wiring, and thorough testing are crucial for a successful conversion that ensures proper vehicle operation and diagnostic capabilities.
