Powertrain, generic · Hybrid propulsion

P0AD9 Hybrid/EV Battery Positive Contactor Control Circuit/Open

Check engine lightOn
EmissionsRelevant
Drive cycleNot required
Limp modePossible

The positive main contactor connects the traction battery to the high-voltage bus; its coil is driven by the battery or hybrid controller. P0AD9 covers an open in this coil circuit. GM documents it in detail: in hybrid tables from model year 2011 the HPC2 sets it on open load during the commanded state, Type B. 2016-19 tables use a control voltage between 1.15 and 2.81 V with the contactor commanded off, 40 of 50 samples at 12.5 ms; 2019 versions also check coil current below 194 mA when on. CARB requires circuit monitoring of hybrid outputs. Low and high faults are P0ADB and P0ADC; a contactor stuck open is P0AA2. The car usually cannot go ready.

Likely causes

Open in the contactor coil or its pigtail inside the battery disconnect unit
Loose or corroded low-voltage connector at the battery disconnect unit
Broken control wire in the battery harness
High-side 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 pos contactorwiring harnessbms

Related codes

P0ADAP0ADBP0ADCP0ADDP0AA2P0AE4

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