For owners of classic Ford OBS (Old Body Style) trucks and Broncos looking to upgrade their engine or comply with modern emissions standards, converting from the older OBD1 system to OBD2 is a common consideration. This article will guide you through the essentials of performing an OBD2 conversion on your OBS Ford, drawing on the experiences of enthusiasts and mechanics who have tackled this swap.
Understanding the OBD2 Conversion for OBS Fords
The transition from OBD1 to OBD2 represents a significant leap in automotive diagnostic and engine management technology. OBD1 systems, prevalent in vehicles like early 90s Ford Broncos and F-Series trucks, are less standardized and offer limited diagnostic capabilities compared to OBD2. OBD2, mandated in the USA for most vehicles from 1996 onwards, provides enhanced emissions monitoring, a standardized diagnostic port, and more detailed engine data.
For OBS Ford owners, particularly those with pre-1996 models, converting to OBD2 often becomes necessary when swapping in a newer engine – like the F4TE block with a roller cam mentioned in enthusiast forums. These newer engines are designed to run with OBD2 systems, and attempting to control them with an older OBD1 setup can lead to performance issues and a lack of essential engine management features.
Key Components for an OBD2 Swap
Successfully converting your OBS Ford to OBD2 involves more than just plugging in a new computer. It’s a comprehensive swap requiring several key components, often sourced from a donor vehicle:
- OBD2 Engine Wiring Harness: This is the central nervous system of your new engine management. The OBD2 harness is significantly different from the OBD1 version, accommodating additional sensors and the OBD2 diagnostic port. The original poster noted the “massive jungle of wires under the OBDII trucks dash,” highlighting the increased complexity.
- PCM (Powertrain Control Module) or EEC (Electronic Engine Control): The “computer box” is the brain of the OBD2 system. You’ll need an OBD2 PCM compatible with your engine and transmission. Matching the PCM to your engine (like a 351w MAF OBDII PCM) is crucial for proper operation.
- Fuel Harness: While potentially integrated into the engine harness, the fuel system wiring might also require updates to be compatible with the OBD2 PCM and fuel delivery requirements of the newer engine.
- Data Link Connector (DLC): This is the standardized OBD2 port that allows you to connect diagnostic scanners and read engine data.
Wiring and Repinning Considerations
One of the most challenging aspects of an OBD2 conversion is integrating the new wiring harness into the existing OBS Ford chassis. As the original poster realized, the OBD2 system involves more connections, especially within the dash and instrument cluster.
Repinning becomes a critical skill. This involves carefully modifying the existing wiring connectors to match the pinouts of the new OBD2 PCM and harness. The original poster specifically asks for PCM layouts for both their 1993 OBD1 Bronco and a 1995 OBD2 F-150 to facilitate repinning. These diagrams are essential for correctly re-routing wires for functions like:
- Automatic 4×4: Ensuring your Bronco’s 4-wheel drive system integrates seamlessly with the new PCM.
- Rear Power Window: Retaining the functionality of your Bronco’s specific features with the OBD2 system.
Forums dedicated to Ford trucks and Broncos, especially F150 forums as suggested by the original poster, are valuable resources for finding these wiring diagrams and guidance from those who have completed similar swaps.
Transmission Compatibility: E4OD and OBD2
The original poster also questions whether to swap the transmission due to OBD2 sensors. Both OBD1 and OBD2 OBS Fords could come with the E4OD transmission. While the core transmission might be similar, OBD2 systems often incorporate additional sensors for enhanced diagnostics and control.
It’s advisable to research the specific year and model of your donor vehicle and compare the E4OD transmission sensors and wiring to your original setup. While a full transmission swap might not always be necessary, understanding potential sensor differences is crucial for a smooth OBD2 integration.
Conclusion: Planning and Research are Key
Converting your OBS Ford to OBD2 is a complex but achievable upgrade. It unlocks the benefits of modern engine management and diagnostics, particularly when installing a newer engine. Success hinges on careful planning, sourcing the correct OBD2 components – ideally from a compatible donor vehicle – and meticulous wiring work, often involving repinning. Leveraging online communities and wiring diagrams specific to your vehicles will be invaluable throughout this conversion process.
