What it means
The positive contactor B of the battery charging system reports a control circuit low condition. HV charging path cannot be commanded reliably.
At a glance
- Usually lights the check-engine light
- The engine or gearbox may go into limp mode
How it works
Positive contactor B is operated by a low-voltage control circuit, while its contacts switch the high-voltage charging path. P2BC9 sets when the control circuit voltage is lower than expected, which can prevent the system from reliably commanding the contactor.
Common causes
Most likely first.
- Control wire shorted to ground
- Internal short in contactor coil
- Connector pins corroded - high contact resistance
Symptoms
- Hybrid-system warning light or message
- Charging may be unavailable
- Vehicle may not enter READY mode
How to diagnose it
- Save freeze-frame data and check contactor B command and status to see when the control-circuit low condition occurs.
- With the system safely powered down, inspect the control wire for a short to ground and the connector for corrosion or damaged terminals.
- Check the circuit’s low-voltage supply and ground under the manufacturer’s test conditions to locate an unintended voltage drop.
- Test the contactor coil and isolated control wiring for a short using the manufacturer’s procedure.
- After repair, clear the code and confirm that contactor B switches as commanded and the vehicle enters READY.
Common fixes
- Repair a control wire shorted to ground.
- Clean or repair corroded contactor B connector pins.
- Replace positive contactor B if its coil is internally shorted under the manufacturer’s test.
Can I keep driving?
If the vehicle will not enter READY or charging is unavailable, arrange service or recovery and do not depend on it for a journey. Leave high-voltage circuit testing to a qualified hybrid 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.