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DTC codes / P2Dxx · Hybrid propulsion / P2D70

P2D70Battery Charging System Negative Contactor D Circuit

P2D70 indicates that the battery charging system's negative contactor control circuit has a fault, as detected by the powertrain control module or battery energy control module. The computer monitors the circuit that commands the negative contactor, which connects the high-voltage battery's negative terminal to the charging system, and it has detected an unexpected voltage or current condition that prevents reliable contactor operation.

SystemPowertrain
Code typeGeneric (all makes)
SeverityHigh
Fix difficultyProfessional
AreaHybrid propulsion

Symptoms you may notice

  • Illumination of the battery charging system warning light or a high-voltage system fault message
  • The vehicle may fail to start or enter a ready-to-drive state because the high-voltage battery cannot connect
  • Reduced or absent charging of the high-voltage battery, leading to a low state of charge over time
  • Intermittent loss of power or a sudden shutdown while driving if the contactor opens unexpectedly
  • Often no symptoms besides the warning light if the fault is stored but the contactor still functions
  • Audible clicking from the battery pack area as the contactor attempts to close repeatedly

Common causes, most likely first

  1. Damaged or corroded wiring in the negative contactor control circuit, including open or shorted conductors
  2. Failed negative contactor coil or mechanical contactor assembly inside the high-voltage battery pack
  3. Poor electrical connection at the contactor control module or battery pack connectors
  4. Faulty battery energy control module or powertrain control module driver circuit for the contactor
  5. Water intrusion or contamination in the battery pack causing corrosion on the contactor terminals
  6. Blown fuse or relay in the contactor control power supply circuit

How to diagnose and fix it

  1. Retrieve all stored codes and freeze-frame data with a scan tool capable of reading high-voltage system modules, then clear codes and verify whether P2D70 returns
  2. Inspect the negative contactor control circuit wiring and connectors for damage, corrosion, or loose pins, repairing as needed
  3. Check the contactor control circuit fuse and relay, testing for power and ground at the contactor coil
  4. Measure resistance across the negative contactor coil and compare to the manufacturer's specification to identify an open or shorted coil
  5. Perform a bidirectional test of the negative contactor with the scan tool to confirm whether the contactor actuates and the circuit responds
  6. If the circuit and coil test good, diagnose the battery energy control module or powertrain control module driver output with an oscilloscope
  7. Replace the faulty contactor, wiring harness, or control module as indicated by the test results, then clear codes and verify proper charging system operation

Contactor Circuit Checks Before Module Replacement

  • A common mistake is replacing the high-voltage battery pack when the actual fault is a chafed control wire near a sharp bracket or a corroded connector pin, so always perform a thorough circuit inspection first.
  • P2D70 can be set by a momentary voltage spike or a low 12-volt battery during cranking, so verify the auxiliary battery is fully charged and stable before condemning high-voltage components.
  • The negative contactor often works in tandem with the positive contactor, and a fault in one can cause the other to set related codes, so review all stored codes together rather than focusing on P2D70 alone.
  • Some vehicles will set this code if the contactor control circuit is tested with a standard test light that draws too much current, so use a high-impedance meter or logic probe to avoid false results.
  • Intermittent contactor faults can be temperature-dependent, so performing wiggle tests and monitoring live data while the vehicle is cold and after warm-up may be necessary to reproduce the condition.

Can I keep driving with P2D70?

Do not continue driving with P2D70 set, because the high-voltage battery may not connect reliably and the vehicle could lose power unexpectedly or fail to start. Have the vehicle inspected by a qualified high-voltage technician before further use.

Tools that help

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Guidance is general and written for all OBD-II vehicles. Exact tests and values vary by model, so confirm the fault before replacing parts.

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