Bulletin No.: PIC6285
Published date: 06/6/2017

Preliminary Information
PIC6285 Diagnostic Aid for DTCs P1AEE and P1AEF, Control Module Hybrid/EV Battery System
Voltage High Voltage (Over-Voltage)
Models
Brand:

Model:

VIN:

Model Years:

from

Engine:

to

Transmissions:

Chevrolet

Volt

2016 - 2018

All

All

All

All

Buick

Velite

2018

All

All

All

All

Involved Region or Country North America, China
Additional Options (RPO)

Condition

N/A
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.
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.
Cause

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
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 multimeter 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
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
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
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
currently under engineering investigation.
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

Labor Time

Category 1 - 3

Use the labor operation for the repair performed

Use published labor operation
time

Category 4

5019989 – Hybrid Electronics - Customer Concern Not Duplicated

Use published labor operation
time

*This is a unique Labor Operation for Bulletin use only.

Version History
Version

1

Modified

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