Bulletin No.: PIC6285C
Published date: 02/8/2019

Preliminary Information
PIC6285C Diagnostic Aid for DTCs P1AEE and P1AEF, Control Module
Hybrid/EV Battery System Voltage High Voltage (Over-Voltage)
Product Investigation Review Required
Models
Brand:
Chevrolet

Model:
Volt

VIN:

Model Years:
2016 - 2019

from
All

Engine:

to
All

All

Transmissions:
All

Involved Region or
Country

North America, China

Condition

Diagnostic Aid for DTCs P1AEE and P1AEF, Control Module Hybrid/EV Battery
System Voltage High Voltage (Over-Voltage)
This document is intended to help diagnose the reason P1AEE and P1AEF set in
the vehicle. When these DTCs set, the control system forces the propulsion
system to become inactive, the READY light will extinguish, and the Malfunction
Indicator Lamp (MIL) will illuminate.

Cause

These diagnostics set within milliseconds of the high voltage system voltage
being over its voltage operating limit. It is the function of the Motor Control
Modules to detect the over-voltage condition, but it is very unlikely that
replacing the T6 Drive Motor Generator Control Module will be the correct
repair. Looking at the freeze frame data captured by the Hybrid Powertrain
Control Module (1), Hybrid Powertrain Control Module 2, and the Drive Motor
Generator Control Modules 1 and 2, is critical to continuing with the diagnosis.
The diagnostics are known to set due to one of four categories. Using the freeze
frame data will help determine which course of action is needed for the repair.
View the freeze frame information for each module individually. To do this in
GDS2, use Module Diagnostics / Diagnostic Trouble Codes (DTC) / Freeze
Frame/Failure Records for each module with codes.

Correction:
Category 1: P1AEE and P1AEF were caused by a loss of isolation condition in the vehicle
Find the following parameters in the HPCM freeze frame:
Auxiliary Transmission Fluid pump motor Negative supply Isolation Voltage
Auxiliary Transmission Fluid pump motor Positive supply Isolation Voltage
Auxiliary Transmission Fluid Pump Motor Negative Supply
Isolation Voltage

0.00

V

Hybrid Powertrain Control Module

Auxiliary Transmission Fluid Pump Motor Positive Supply
Isolation Voltage

-257.32

V

Hybrid Powertrain Control Module

If one of these parameters is 0 volts in the freeze frame, then it is likely the vehicle has a loss of
isolation condition.

If accompanied by DTCs P1AF0/P1AF2/P1E22 or P0C01/P0C04, then the loss of isolation will be located
within the transmission, usually due to debris in the motor stators from a failed internal component.
Without the accompanying DTCs, the loss of isolation could be anywhere within the high voltage system,
but the transmission is still suspect.
Use the Loss of Isolation on the High Voltage Main Bus procedure in SI to help pinpoint which subsystem
is causing the loss of isolation.
Using the vehicle data to help determine the loss of isolation is preferred to troubleshooting with an
insulation multi-meter due to the intermittent nature of most failures.
Note: Any loss of isolation will not self-heal and needs to be repaired for vehicle safety. Clearing codes
without repair is not an acceptable remedy of this category due to the vehicle hazards created by P1AEE
and P1AEF.

Examples of debris causing stator problems:

Category 2: P1AEE and P1AEF were caused by the high voltage contactors opening
unexpectedly
Find the following parameters in the HPCM freeze frame:
Auxiliary Transmission Fluid pump motor Negative supply Isolation Voltage
Auxiliary Transmission Fluid pump motor Positive supply Isolation Voltage
Auxiliary Transmission Fluid Pump Motor Negative Supply
Isolation Voltage

167.29

V

Hybrid Powertrain Control Module

Auxiliary Transmission Fluid Pump Motor Positive Supply
Isolation Voltage

302.79

V

Hybrid Powertrain Control Module

If the value for Negative Supply Isolation Voltage in the freeze frame is within 40 volts of 165v, then the
high voltage contactors in the battery opened unexpectedly while the vehicle was driving.
The vehicle may also have a P0AA1 and P0AA4 set for this category. If the HPCM2 also stored DTC P0A0C
at the same time as P1AEE and P1AEF, then follow published Service Information for P0A0C first.
The HPCM2 has direct control of the contactors. Issues with the HPCM2 or wiring could lead to P1AEE
and P1AEF.
Inspect circuits 3961 and 3959 for contactor control as well as B+ 5240 and ground circuit 2050 (G302).
Any compromise in these circuits may cause the contactors to open unexpectedly.
If no trouble is found, replace the K114B HPCM2 module for a possible internal fault with contactor
control.
Example of connector X357 with stone impingement and corrosion on wiring:

Example of loose ground G302:

Category 3: P1AEE and P1AEF caused by a loose or intermittent orange high voltage cable
connection
Find the following parameters in the HPCM freeze frame:
Auxiliary Transmission Fluid pump motor Negative supply Isolation Voltage
Auxiliary Transmission Fluid pump motor Positive supply Isolation Voltage
Auxiliary Transmission Fluid Pump Motor Negative Supply
Isolation Voltage

394.42

V

Hybrid Powertrain Control Module

Auxiliary Transmission Fluid Pump Motor Positive Supply
Isolation Voltage

1.65

V

Hybrid Powertrain Control Module

This is expected to be a less common category for P1AEE and P1AEF. If one of the parameters is near
but not equal to zero, properly inspect each of the orange high voltage connectors on the vehicle for a
loose connection on the high voltage bus.
Example of a loose connector X2 at the K10 Coolant Heater Control Module:

Category 4: P1AEE and P1AEF caused by a contactor timing issue
Find the following parameters in the HPCM freeze frame:
Auxiliary Transmission Fluid pump motor Negative supply Isolation Voltage
Auxiliary Transmission Fluid pump motor Positive supply Isolation Voltage
Auxiliary Transmission Fluid Pump Motor Negative Supply
Isolation Voltage

92.08

V

Hybrid Powertrain Control Module

Auxiliary Transmission Fluid Pump Motor Positive Supply
Isolation Voltage

-311.73

V

Hybrid Powertrain Control Module

If the customer complaint was a failure to start one time, compare the freeze frame data with the values
above.
If the Engine Run Time parameter is equal to zero, and both voltages are within 20 volts of the values
above, then this condition is a charger control issue.
This rare condition is mostly seen in the winter months during a remote start while the car is plugged
in.
P1AEE and P1AEF will be the only codes in the HPCM for this condition.
The hardware on the vehicle is not suspect at this time. Letting the control modules sleep will allow the
vehicle to attempt another crank event.
For this category only, the codes may be cleared and the vehicle released to the customer because no
vehicle safety hazard exists for this category.
If needed, explain to the customer how to let the vehicle sleep in order to try another crank attempt.
This is done by pushing the power button briefly without pressing the brake pedal, and exiting the car
for about one minute.

Warranty Information
Labor Operation

Description

Category 1 - 3

Use the labor operation for the repair performed

Category 4

5019989 – Hybrid Electronics - Customer Concern
Not Duplicated

Labor Time
Use published labor
operation time
Use published labor
operation time

Version History
Version
Modi ed

4
06/06/2017 - Created
10/11/2017 - Updated to add table information to Correction Section
10/01/2018 Updated to added model year 2019
02/08/2018 - Updated wording in Category 4.

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