Experiencing trouble getting your OBD2 scan tool to communicate with your Holden Commodore, especially an older model with an LS1 engine? It’s a frustrating situation when that engine light pops on, and you’re left in the dark about the fault codes. Let’s dive into why your scan tool might be failing to read codes on your Commodore and explore some troubleshooting steps.
You’re not alone if you’re facing this issue. Many Holden Commodore owners with earlier OBD2 systems, like the 2002 VY SS Commodore with the Chevrolet LS1 engine, which uses the SAE J1850 VPW protocol, run into similar roadblocks. The dreaded engine symbol with the lightning bolt – the check engine light – signals an EFI system problem.
The real headache begins when your OBD2 scanner, despite claiming GM compatibility, refuses to recognize any fault codes. Imagine the frustration of trying to diagnose the issue yourself, only to be met with a scanner that seems unresponsive. For some, like one Commodore owner, the scan tool might have worked once years ago for a specific issue like an evaporative emission control system leak, recording a stored trouble code, but then never connecting again for fault retrieval. Typically, these scanners might still display live engine data, offering a glimmer of functionality, but failing at the crucial task of code reading.
Trying a different scan tool might seem like the next logical step. Perhaps a budget-friendly option bought online, used previously on a different make like a Mitsubishi (which operates on a different diagnostic system than General Motors), could do the trick? Unfortunately, the outcome often remains the same. You plug in the new scanner, hoping for a different result, but are met with the same inability to retrieve stored trouble codes or even pending codes.
It’s important to note that even if there aren’t any stored trouble codes severe enough to trigger the check engine light, there might still be pending codes that could offer valuable diagnostic information. However, in these situations, even pending codes remain elusive, leaving you with no concrete fault information.
Understanding your car’s OBDII system is crucial. For instance, the 2002 Holden Commodore utilizes pin 2 on the OBDII port for the signal wire, operating on the older SAE J1850 VPW protocol. In contrast, newer Holden models, like a 2014 Holden Colorado, employ the ISO 15765 or CAN BUS system (standard in Holdens since 2006), using pins 6 & 14 for signal wires. To verify scan tool functionality, a simple test can be performed on a newer vehicle. Disconnecting the MAF sensor on a CAN BUS vehicle should trigger a fault code, which a working scanner should then detect.
In such a test scenario on a newer Holden Colorado, disconnecting the MAF meter indeed resulted in a pending P0113 code, which both scan tools successfully read. This confirms that the scan tools are capable of reading codes on a compatible vehicle using a different OBDII protocol.
This raises a critical question: could both scan tools be faulty specifically in their ability to read codes from the older SAE J1850 VPW protocol used in your Commodore? It’s plausible that a hardware limitation within these potentially copied, budget-friendly scan tools hinders their compatibility with this specific protocol, while live data functionality remains operational.
The assertion that Australian LS1-powered Commodores are fundamentally different from US models and somehow OBD1.5 is generally inaccurate and often stems from confusion with older Buick V6-powered Commodores which were indeed OBD1.5 until 2004. Your 2002 LS1 Commodore should be OBD2 compliant, but the protocol compatibility remains the key issue.
So, what’s the best course of action and the best value-for-money scan tool for an LS1 Holden Commodore? Before investing in another scan tool, especially a Vgate VS890 or similar, it’s wise to investigate further. Consider using an oscilloscope to scope pin 2 of your OBDII port to confirm whether a trouble code signal is even being transmitted. This step can help determine if the issue lies with the car’s signal output or the scan tools’ input and compatibility. Ruling out a signal issue from the car itself can save you from investing in more scan tools that might also prove ineffective.
