Powertrain, generic · Hybrid propulsion

P0ADD Hybrid/EV Battery Negative Contactor Control Circuit/Open

Check engine lightOn
EmissionsRelevant
Drive cycleNot required
Limp modePossible

The negative main contactor closes the return path of the traction battery; P0ADD reports an open in its coil drive circuit. GM documents the code in parallel to the positive side: tables since model year 2011 detect open load in the HPC2 and store it after two trips; 2016-19 tables evaluate a control voltage between 1.15 and 2.81 V while off, 40 of 50 samples, Type B, and 2019 tables add a coil current check below 194 mA when on. CARB 1968.2 covers this circuit monitoring of hybrid components. Related codes are P0ADF and P0AE0 for low and high, P0AA5 for a contactor stuck open, P0AD9 for the positive side. Without this contactor the HV system stays off.

Likely causes

Open in negative contactor coil or its pigtail
Loose or corroded connector at the battery disconnect unit
Broken control wire in the battery harness
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

P0ADEP0ADFP0AE0P0AD9P0AA5P0AA3

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