File in Section:

Service Bulletin

Bulletin No.:
Date:

PIC5920
October, 2013

PRELIMINARY INFORMATION
Subject:

Vehicle Will Not Charge And Hybrid Loss Of Isolation With DTC P0AA6 And/Or P1F0E

Models:

2011-2014 Chevrolet Volt
2014 Cadillac ELR
2014 Opel Ampera

The following diagnosis might be helpful if the vehicle exhibits the symptom(s) described in this PI.

Condition/Concern
Some customers may comment that their vehicle will not charge. Customers may also comment that a Check Engine
Lamp is illuminated. Technicians may find a current code P0AA6 And/Or P1F0E set in the HPCM2. Potential causes
to consider when evaluating the vehicle for P0AA6 are:
1. A loss of isolation due to a Hybrid/EV Battery Heater
2. Hybrid Battery Contactor Assembly function failure
3. A loss of Hybrid/EV Battery Pack coolant (external or internal to the Hybrid/EV Battery Pack)
4. A loss of high voltage isolation within the battery cells or battery sections themselves
5. Hybrid battery cooling system not filled entirely with GM approved 50/50 coolant.

Recommendation/Instructions
Inspect Hybrid/EV Battery Pack coolant level. If coolant level is low or there is evidence of a coolant leak, refer to the
Hybrid/EV Battery Cooling System Diagnostic in Service Information.
Important: All P0AA6 failures must include an inspection of the Hybrid/EV Battery Pack drain plug, located on the
battery tray, regardless of fluid level at the Hybrid/EV Battery Pack coolant reservoir. If any moisture is found during
the drain plug inspection, contact the GM Technical Assistance Center (TAC).
Test the Hybrid/EV Battery Pack coolant concentration using the J-26568 Refractometer. Ensure freeze point is
between -10 and -40 degrees F. In the absence of a J-26568 Refractometer, dealer may use a Hydrometer. If outside
that window, flush and refill with GM approved 50/50 coolant (GM Part Number: 12378390)
To evaluate Hybrid/EV Battery Heater or Hybrid Battery Contactor Assembly function, first determine if any additional
codes are current. Follow service information for any current codes. If no Hybrid Battery Contactor Assembly or
Hybrid/EV Battery Heater diagnostics are set, technician should still follow the heater testing procedure as defined in
SI under Circuit/System Verification for DTC: P1EC6, to confirm the heater is functioning properly.
Additional data required for Engineering (via TAC) for inclusion into the TAC case:
Put the vehicle in Service Mode (Press the start/stop button for 10 second without depressing the brake pedal) and
record the following information using GDS:
MODULE

DATA PARAMETER

Drive Motor 1

Hybrid/EV Powertrain Control Module High
Voltage Circuit

Value
V

Drive Motor 1

Drive Motor 1 Control Module Negative Supply
Isolation Voltage

V

Drive Motor 1

Drive Motor 1 Control Module Positive Supply
Isolation Voltage

V

Drive Motor 2

Hybrid/EV Powertrain Control Module High
Voltage Circuit

V

Drive Motor 2

Drive Motor 2 Control Module Negative Supply
Isolation Voltage

V

Drive Motor 2

Drive Motor 2 Control Module Positive Supply
Isolation Voltage

V

Battery Energy Control Module

Hybrid/EV Battery Pack Terminal 1 Voltage

V

MODULE

DATA PARAMETER

HPCM2 (voltage data list)

Hybrid/EV Battery Pack Capacity

HPCM2

Isolation Test Resistance

Value
Kohm

With the vehicle in the Ignition Off Position, record the following information using GDS. (You will need to hold your
foot on the brake pedal or turn on parking lights to ensure the data bus remains awake to communicate with the
vehicle in the Off Position.)
MODULE

DATA PARAMETER

HPCM2

High Voltage System Isolation Test Status

HPCM2

Isolation Test Resistance

Value

Danger: Always perform the High Voltage Disabling procedure prior to servicing any High Voltage
component or connection. Personal Protection Equipment (PPE) and proper procedures must be followed.
The High Voltage Disabling procedure includes the following steps:
• Identify how to disable high voltage.
• Identify how to test for the presence of high voltage.
• ·
Identify condition under which high voltage is always present and personal protection equipment (PPE)
and proper procedures must be followed.
Before working on any high voltage system, be sure to wear the following Personal Protection Equipment:
• Safety glasses with appropriate side shields when within 15 meters (50 feet) of the vehicle, either indoors or
outdoors.
• ·
Certified and up-to-date Class "0" Insulation gloves rated at 1000V with leather protectors.Visually and
functionally inspect the gloves before use.
Wear the Insulation gloves with leather protectors at all times when working with the high voltage battery assembly,
whether the system is energized or not.
Failure to follow the procedures may result in serious injury or death.
With vehicle OFF, 12 volt battery disconnected, and Manual Service Disconnect (MSD) removed, measure and
record voltage across MSD base high voltage terminals, at top of Hybrid/EV Battery Pack. Measure and record
voltage from each MSD base high voltage terminal with reference to vehicle chassis ground. In each case allow the
volt meter voltage reading to settle for 2 minutes before recording value.
Gather all measurements recorded while evaluating P0AA6 and contact the GM Technical Assistance Center for
inclusion into the TAC case.

Warranty Information
The correction for this concern may be one of several repairs described above. For vehicles repaired under warranty,
please use the appropriate warranty labor operation based on the original cause in addition to well documented
straight time.
Please follow this diagnostic or repair process thoroughly and complete each step. If the condition exhibited is
resolved without completing every step, the remaining steps do not need to be performed.