What it means
The control circuit of the HV battery negative contactor reports a control circuit low condition. HV main switching 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
The negative contactor connects the battery pack to the high-voltage system, and its control circuit tells the contactor when to close or open. P0ADF sets when the control module detects a circuit signal below the expected range, which can happen if the control wire is grounded or the coil is shorted. The pack may not switch high voltage reliably.
Common causes
Most likely first.
- Control wire shorted to ground
- Internal short in coil
- Connector pins corroded - high contact resistance
Symptoms
- EV/hybrid system warning light on
- Reduced power output or limp mode
- Charging may fail or be slowed
- Reduced electric range
How to diagnose it
- Review freeze-frame and live data for the negative-contactor command and circuit status to confirm when the low condition occurs.
- With the vehicle safely powered down, inspect the negative-contactor control wiring for chafing or a short to ground, and check its connector pins for corrosion.
- Test the control wire for an unintended ground using the manufacturer's procedure.
- Measure the negative-contactor coil and circuit resistance against the manufacturer's specification to check for an internal short or excessive connection resistance.
- If wiring and coil tests pass, use a capable scan tool to compare the commanded and reported negative-contactor state and investigate the control module circuit.
Common fixes
- Clean and secure corroded negative-contactor connector pins.
- Repair a control wire shorted to ground or damaged harness section.
- Replace the negative contactor if its coil is shorted or outside specification.
- Repair the control module or its connection if testing isolates the fault there.
Can I keep driving?
Avoid routine or long-distance driving because reduced power, limp mode, or failure to enter Ready mode may occur. Arrange prompt hybrid-system diagnosis; the vehicle may also be unable to charge reliably.
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.