Powertrain, generic · Hybrid propulsion

P0ADF Hybrid/EV Battery Negative Contactor Control Circuit Low

Check engine lightOn
EmissionsRelevant
Drive cycleNot required
Limp modePossible

P0ADF reports that the drive circuit of the negative main contactor is pulled too low, typically a short to ground in the coil line. GM documents the code in its 2016-19 hybrid tables: control voltage below 5.35 V while the contactor is commanded on, 13 of 16 samples at 12.5 ms (20 of 25 in one 2016 group), Type B with two trips, enabled above about 9 to 10 V on the 12 V system. CARB 1968.2 requires this kind of circuit monitoring for hybrid outputs. Counterparts are P0ADD (open), P0AE0 (high) and, on the positive side, P0ADB. As the contactor cannot close properly, the high-voltage system does not come up and the vehicle will not drive or charge.

Likely causes

Coil control wire shorted to ground
Negative contactor coil internally shorted
Moisture in the battery disconnect unit connector
Driver in the battery controller defective

Symptoms

  • Vehicle will not enter ready mode or start
  • Hybrid or EV warning light and check engine light
  • Charging not possible

Repair estimate

DifficultyShop_onlyWorkshop job
Parts and labour€100–2,500
Time1–5 h

Typical range across vehicles; the real cost depends on what the testing finds.

Parts involved

hv battery neg contactorwiring harnessbms

Related codes

P0ADDP0ADEP0AE0P0ADB

References: gsi.ext.gm.com, law.cornell.edu, gsi.ext.gm.com.