The P0608 code in your 2023 Chevrolet Equinox indicates that the engine control module (ECM) has detected a malfunction in its vehicle speed sensor (VSS) output A circuit. This code doesn't necessarily mean your speed sensor is bad—rather, it points to a problem with the ECM's ability to properly output the vehicle speed signal to other modules.
Understanding ECM VSS Output
Your Equinox's ECM receives vehicle speed data and then redistributes this information to other systems that need it. The speedometer, transmission control module, stability control system, and cruise control all rely on this distributed speed signal. When the ECM's output circuit fails, these systems lose their speed reference.
Symptoms of VSS Output Failure
The speedometer may read zero or erratically while driving. Cruise control won't engage or maintain speed. The transmission may shift harshly or refuse to shift from first gear. Stability control and ABS warning lights may illuminate due to loss of speed data. These symptoms occur because multiple systems depend on the ECM's speed signal output.
Diagnostic Approach
Using GM GDS2 or an advanced scan tool, verify that the ECM is receiving vehicle speed data from the transmission. If the input is good but the output circuit is dead, the problem lies within the ECM itself. Check the wiring between the ECM and other modules for shorts or opens. Inspect ECM connectors for corrosion, bent pins, or damage that might affect the VSS output circuit.
Repair Options
If wiring issues are found, repair them and clear the code. If the ECM's internal VSS output driver has failed, the module requires replacement. Your 2023 Equinox is under factory warranty, which covers ECM failures. The replacement module must be programmed with vehicle-specific data including VIN, options, and theft deterrent registration.