P2DD0: Control Pilot Charging Switch B Circuit Low

What it means

The control pilot charging switch B reports a circuit low condition. SAE J1772 charging signal handshake may be compromised.

At a glance

• Usually lights the check-engine light

How it works

Control pilot charging switch B is monitored as part of the signal path used during the charging handshake. P2DD0 sets when the module detects the switch B circuit voltage or signal staying below its expected range, which can result from a short to ground or a fault at the switch or connector.

Common causes

Most likely first.

1. Wire shorted to ground
2. Switch shorted
3. Connector pins corroded - high contact resistance

Symptoms

• Charge status indicator shows fault
• Charging may not start or interrupts
• Slower-than-expected charge rate

How to diagnose it

1. Review freeze-frame and live switch B circuit data during a charging attempt to confirm the low condition is present.
2. Inspect the switch B harness for crushed or rubbed-through insulation that could let the wire contact ground.
3. Check the switch connector for corrosion, damaged terminals, or a poor connection that could pull the signal low.
4. Test the switch B signal wire for a short to ground and check the switch response using the manufacturer's wiring diagram and specification.
5. If the external circuit tests correctly, verify the charging controller input before replacing parts.

Common fixes

• Repair wiring shorted to ground in the switch B circuit.
• Clean or replace corroded or damaged connector terminals.
• Replace a switch B assembly that tests shorted or fails to respond correctly.
• Repair the controller input only if the circuit and switch pass testing.

Can I keep driving?

Driving is generally unaffected, but charging may not start or may stop unexpectedly, so confirm the vehicle has enough charge before setting out. Do not keep using a damaged or overheating charging connector.