Experiencing trouble connecting your Bosch OBD scanner to your Chevy truck? Many enthusiasts and mechanics rely on scan tools like Bosch models for diagnostics, but encountering a “no communication” error can be frustrating, especially with older OBD-I systems. This article delves into a common scenario where a user faced this exact issue when trying to diagnose a modified Chevy truck. We’ll explore the troubleshooting steps taken and potential solutions, focusing on how to get your Bosch scanner to communicate effectively and whether issues could be related to something as simple as the Bosch Obd 1 And 2 Scanner Power Cord.
The problem began when a user attempted to use their Bosch OBD1300 scan tool on an older Chevy truck that had undergone an engine swap. The truck, originally equipped with an OBD-I system, now housed a modified Vortec 350 engine. Despite the engine running, albeit with some lean fuel mixture symptoms like stumbling and exhaust popping, the Bosch scanner failed to establish a connection with the truck’s computer (ECM).
An engine bay similar to a Chevy truck, highlighting the complexity of engine swaps and potential diagnostic challenges.
Initial troubleshooting steps confirmed the issue wasn’t just the Bosch OBD1300 scanner itself. An older DLC plug-in device intended to flash OBD-I trouble codes also yielded no response. Even manually jumpering the A and B terminals on the ALDL (Assembly Line Diagnostic Link) connector, a traditional method for retrieving codes on OBD-I systems, proved ineffective. Adding to the confusion, there was no “check engine” light illuminated, only a persistent “check gages” light.
To further investigate the communication problem, the user meticulously checked the ALDL connector pinouts with the key in the ‘key on, engine off’ position. The readings were as follows:
- Position A: 0 ohms to ground (Expected Ground)
- Position B: 5.05 volts (Expected ECM Diagnostic Request/Data Stream)
- Position C: 0 volts (Expected Ground)
- Positions D, E, and F: Not used
- Position G: 0 volts (Expected Ground)
- Position H: 9.68 volts (Suspected ABS System Voltage)
- Position J: 0 volts (Expected Ground)
- Positions K and L: Not used
- Position M: 5.01 volts (Suspected Data Stream)
A generic OBD1 ALDL connector pinout diagram, illustrating the different pins and their typical functions in a GM OBD1 system.
These readings, while providing some information, didn’t immediately pinpoint the communication breakdown. The presence of voltage at pin B and M suggested power was reaching the ALDL connector, but the lack of scanner response indicated a deeper issue. Could a faulty ECM be the culprit? Or was there a compatibility problem between the Bosch OBD1300 and this specific OBD-I implementation?
One crucial aspect to consider when troubleshooting scanner communication problems is the power supply to both the vehicle’s diagnostic system and the scan tool itself. While the ALDL pinout checks hinted at power reaching the connector, it’s always worth verifying the bosch obd 1 and 2 scanner power cord and its connections, especially if using an older scanner model. Ensure the power cord is securely connected to both the scanner and a reliable power source, typically the vehicle’s battery or a designated power outlet in the vehicle. Although less likely in this specific scenario given the ALDL pin readings, a weak or interrupted power supply to the Bosch scanner can sometimes mimic a no-communication issue.
In this case, the user suspected the ECM itself might be the issue, especially given the truck’s modifications and unknown history. The lean running condition further suggested potential computer problems. Possible next steps for diagnosing this no-communication issue include:
- Verifying ECM Ground and Power: Directly check the ECM’s power and ground connections to rule out a basic wiring fault.
- ECM Replacement (as a test): If easily accessible and affordable, trying a known good ECM of the correct type could help determine if the original ECM is faulty.
- Consulting Wiring Diagrams: Referencing wiring diagrams specific to the truck and engine combination can help trace the diagnostic communication circuits for breaks or shorts.
- Scanner Compatibility Check: Double-check the Bosch OBD1300 scanner’s compatibility list to ensure it officially supports the specific year and model range of the Chevy truck, despite being marketed as an OBD-I tool.
A mechanic using a scan tool in a vehicle, representing the diagnostic process and the reliance on scanners for modern vehicle repair.
While the bosch obd 1 and 2 scanner power cord might not be the primary suspect in this complex OBD-I communication failure, ensuring a stable power supply to your diagnostic tools is always a fundamental step in any troubleshooting process. For this Chevy truck, further investigation into the ECM and wiring system is crucial to restore diagnostic capabilities and address the underlying engine performance issues.
