P2DD4

Code

Generic P — Powertrain

Control Pilot Charging Switch B Stuck On

Brand: Generic

Type: P — Powertrain

Views: UK: 20 EN: 30 RU: 20

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Page language: EN

DTC P2DD4 stored and possibly a charging-system warning lamp or message
Charge session will not negotiate correctly or cannot be stopped
Control pilot signal shows incorrect/continuous active state
Vehicle may show continuous readiness to accept charge or won’t accept charge commands
Possible inability to start or stop charging; erratic behavior with different chargers

Visual inspection of charging inlet, connectors and wiring for damage, moisture or corrosion
Use a scan tool to read live data for Control Pilot states and stored freeze frame data
Measure voltage and waveform on the control pilot / Switch B line with a scope or meter
Disconnect external charger (EVSE) and see if DTC persists when vehicle isolated
Perform continuity and resistance checks on Switch B circuit (powered-off) to verify open/closed state
Inspect and test vehicle-side charging relay / contactor or driver FET for proper function

Control pilot expected to switch between active and idle states; verify presence of PWM waveform when charging negotiation is in progress
Typical control pilot signal is a low-voltage logic/PWM signal (refer to vehicle-specific service data for exact voltages and PWM frequency)
When Switch B is OFF the circuit should show high impedance / open; when ON it should show near 0 Ω continuity to the switched reference
Look for abnormal constant voltage or continuous continuity on Switch B when commanded OFF

Safety first: disable high-voltage systems per manufacturer procedure and wear appropriate PPE.
Connect a diagnostic scan tool, read and record freeze frame and live data related to charging pilot and charging module.
Clear the code and attempt to reproduce. Note whether the code returns and under what conditions (with/without EVSE connected).
Visually inspect the charging inlet, mating connector and wiring harness for damage, corrosion, moisture or foreign objects.
With vehicle power off, check continuity/resistance of the Switch B circuit between the control module pin and the switch output; verify open when switch commanded OFF.
Power the charger control circuit and use an oscilloscope or meter to view the control pilot waveform and the Switch B state while commanding the switch ON and OFF from a scan tool.
If Switch B remains ON while commanded OFF, isolate at the switch (disconnect harness) and test again to determine if fault is upstream (wiring/charger) or module internal.
Inspect and test the relay or power transistor that implements Switch B. Replace the relay/FET if found shorted or welded.
If wiring and hardware check good, inspect and test charging module / ECU driver output; consider software update or module replacement per service manual.
After repairs, clear codes and perform a complete charging session test with a known-good EVSE to confirm proper operation.