What it means
The high-voltage service disconnect circuit reports a circuit performance condition. Safe HV disconnection state cannot be verified.
At a glance
- Usually lights the check-engine light
- The engine or gearbox may go into limp mode
How it works
The high-voltage service disconnect separates the traction battery from the rest of the high-voltage system, and a low-voltage monitoring circuit reports whether its state is recognized. This performance code indicates that the circuit behaves outside its expected operating performance, often because aged switch contacts or a high-resistance connection make the signal unreliable.
Common causes
Most likely first.
- Switch contacts aged
- High-resistance contact
Symptoms
- Hybrid-system warning light may illuminate
- Vehicle may limit or disable hybrid operation
- Vehicle may fail to enter or remain in ready mode
How to diagnose it
- Record freeze-frame data and check related hybrid codes to learn whether the disconnect signal fault occurs during startup, vibration, or another operating condition.
- Confirm from the owner's manual that the service disconnect is fully seated in its normal position without removing or handling it.
- With the vehicle powered down, inspect accessible low-voltage disconnect-circuit connectors and wiring for looseness, corrosion, or heat damage.
- Have the disconnect circuit signal and contact resistance checked against the manufacturer's procedure, including connections at the switch.
- If wiring and connections meet specification, have a qualified hybrid technician assess the service disconnect contacts for wear.
Common fixes
- Repair a loose or corroded low-voltage connector in the service disconnect monitoring circuit.
- Repair damaged wiring or terminals causing excess resistance.
- Replace a service disconnect with worn contacts when testing confirms the performance fault.
- Verify the disconnect state is recognized and confirm the code does not return.
Can I keep driving?
If the vehicle limits hybrid operation or cannot stay in ready mode, do not continue driving; arrange safe transport. Since the module cannot reliably confirm the high-voltage disconnect state, leave the disconnect and high-voltage system to a qualified technician.
A code shows where the control module detected a fault, not always which part failed. Check the causes in order and confirm with a test before replacing parts. Have several codes? Check them together
This is a generic code: it means the same on every make. The car’s maker may add more detail in its own service information.