P2D70

Code

Generic P — Powertrain

Battery Charging System Negative Contactor D Circuit

Brand: Generic

Type: P — Powertrain

Views: UK: 27 EN: 34 RU: 21

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Page language: EN

Causes

Open or shorted wiring in the negative contactor D control circuit
Corroded, loose, or damaged connector at the contactor or control module
Failed contactor coil (stuck open or welded contacts)
Blown fuse or faulty relay supplying the contactor coil
Control module (HV battery management/VCU) output or driver fault
Poor ground or supply voltage to the contactor coil

Symptoms

HV battery negative contactor refusing to close or open on command
Charging disabled or charging error messages displayed
Battery/HV system warning indicator illuminated
Reduced vehicle propulsion or limp-home mode
Intermittent faults that may clear then reappear after vibration or moisture exposure

What to check

Observe vehicle warnings and record freeze-frame/related DTCs with a scan tool
Visually inspect contactor, connectors, harness and nearby components for damage, corrosion, heat or water ingress
Check for blown fuses or tripped relays in the low-voltage circuit that powers the contactor coil
With vehicle de-energized, check connector pins for corrosion, bent pins, or poor terminal fit
Measure continuity of the contactor coil (de-energized) and compare to specification (expect low resistance)
With appropriate safety procedures and HV system powered as required, command the contactor close/open via scan tool and verify operation and coil drive voltage

Signal parameters

Contactor coil resistance: low ohms when measured cold (expect a low-value continuity; compare to OEM spec)
Control/drive voltage when commanded CLOSED: near low-voltage supply (typically battery control voltage; e.g., ~9–16 V depending on system)
Control/drive voltage when commanded OPEN: ~0 V (or high-impedance)
When CLOSED: continuity between negative battery terminal and pack negative should be present; when OPEN: high resistance/isolation expected
Look for intermittent changes in coil voltage or resistance during vibration or moisture exposure

Diagnostic algorithm

Safety first: follow high-voltage safety procedures and isolate the HV system (service disconnect) before working on contactors or the HV pack.
Scan tool: read and record P2D70 and any related codes; capture live data and attempt to command negative contactor D while monitoring status.
Visual: inspect contactor, mounting, surrounding harness and connectors for damage, corrosion, loose fasteners, or water/heat damage.
Fuses/relays: verify any fuses or low-voltage relays that supply the contactor coil are intact and operative.
Connector check: with HV system de-energized, disconnect the contactor connector and inspect pins; clean and repair as necessary.
Coil continuity: measure coil resistance (with service plug removed and HV isolated). If infinite or very high → open coil. If near 0Ω → possible shorted coil. Compare to OEM spec.
Ground and supply: verify the low-voltage supply and ground to the coil are correct. Reconnect, power vehicle low-voltage system, command contactor with scan tool and measure drive voltage at command pin.
Functional test: with proper safety procedures, command the contactor closed and verify pack negative continuity and that the vehicle allows charging/operation. Listen/feel for mechanical operation (click).
If coil and wiring are good but command output from control module is absent or incorrect, suspect module driver fault; check for other module DTCs and perform module-level diagnostics.
If contactor is mechanically sticking or welded, remove and replace the contactor assembly and retest.
Clear codes and perform end-of-repair verification including multiple open/close cycles and road/charge test as required.

Likely causes

Damaged harness or pin corrosion at negative contactor D connector
Contactor coil failure (open circuit or short to chassis)
Blown inline fuse or failed low-voltage relay feeding the coil
Control module driver transistor failure or internal fault

Fault status

⚠️ Status

Battery charging system negative contactor D circuit fault — open, short or incorrect control signal detected. Charging or HV connection may be disabled.

🔴 Repair difficulty: Hard

⏱️ Diagnostic time: 1.0-3.0 hours