GM Bulletin No.: 12238C
Date: January 2013

Service Bulletin

SERVICE UPDATE
SUBJECT:

Service Update for Inventory Vehicles Only
Loss of Battery Charge – Inspect Generator Control Module
Expires October 31, 2013

MODELS:

2012-2013 Buick Regal
2012-2013 Buick LaCrosse
2013 Chevrolet Malibu Eco
Equipped with eAssist

The Part Information section has been updated to include an additional part number, and
the Service Procedure has been revised to clarify instructions. All technicians should
review the revised service procedure immediately.
Please discard all copies of bulletin 12238B.
This service update involves vehicles in dealer inventory only and will expire October 31,
2013.
PURPOSE
This bulletin provides a service procedure to inspect and replace, if necessary, the Generator
Control Module (GCM) on certain 2012-2013 model year Buick LaCrosse and Regal, and 2013
model year Chevrolet Malibu Eco vehicles, equipped with eAssist. The GCM may not function
properly, resulting in the gradual loss of battery charge, illumination of the MIL, and eventual
engine stall or no start condition.
This service procedure should be completed on involved vehicles currently in dealership
inventory as soon as possible but no later than October 31, 2013, at which time this
bulletin will expire.
VEHICLES INVOLVED
All involved vehicles are identified by VIN in the Global Warranty Management System –
Investigate Vehicle History Application. Dealership technicians should always check this site to
confirm vehicle involvement prior to beginning any required inspections and/or repairs. It is
important to routinely use this tool to verify eligibility because not all similar vehicles may be
involved regardless of description or option content.
Copyright 2013 General Motors. All Rights Reserved.

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January 2013

Bulletin No.: 12238C

Additionally, a list of involved vehicles currently in dealer inventory is available on the “Service
Update Bulletin Information” link under the “Service” tab in GM GlobalConnect (US) or attached
to the GlobalConnect message (Canada) used to release this bulletin.
PART INFORMATION
Parts required to complete this service update are to be obtained from General Motors
Customer Care and Aftersales (GMCC&A). Please refer to your “involved vehicles listing”
before ordering parts. Normal orders should be placed on a DRO = Daily Replenishment Order.
In an emergency situation, parts should be ordered on a CSO = Customer Special Order.
Part Number
12635717*
12650851*

Description
MODULE, GEN CONT (all 2012 MY & 2013 Malibu)
MODULE, GEN CONT (2013 LaCrosse, Regal)

Quantity/Vehicle
1 (If Req'd)
1 (If Req'd)

* Approximately 10% of vehicles will require replacement of the Generator Control Module.
SERVICE PROCEDURE
Caution: This service procedure is intended to fully stress the generator control module
beyond normal customer use. This stress, in rare cases, may result in smoke and thermal
damage to the generator control module. For the extended idle portion of the service
procedure (Steps 8 and 12), the vehicle should be located outdoors, with the right rear
seat back down, and with the location of the power pack in view of an observer in the left
rear seat during the complete idle portion. Do not remove any trim panels. If smoke is
observed or smelled, even a trace level, or a popping or unusual noise is heard from the
power pack, immediately turn off the engine and exit the vehicle. Continue to observe
vehicle for 10 minutes, making sure event has subsided. Connect GDS tool, key on to
RUN, and acquire freeze frame data from ECM and SGCM. Disconnect the 12V battery
and then contact TAC.
Note: Perform the Generator Control Module inspection to determine if the Generator Control
Module requires replacement. The inspection will take about 3 hours to complete.
- If a module fails the test contained in this bulletin and is replaced, the new module must
also be tested using the procedure contained in this bulletin.
- If the new module fails the test, install another module and perform the test again.
- All testing of modules is to be submitted using the labor code contained in this bulletin. If
module replacement is required, the part cost and labor time to perform the replacement are
to be submitted using the normal warranty labor code and time.
Note: Verify the 175 amp fuse torque and APM cable crimp at the UBEC stud end of the cable
prior to performing the inspection below.
Install GDS2 to vehicle. Enter current vehicle make model. Select Module Diagnostics / HPCM /
Data Display / 14V Power Module menu. If any one of the following DTCs set, replace
Generator Control Module (GCM); P1AF0, P1B0B, P1E0C, P1E12.
1.

Start engine and confirm the vehicle has enough fuel for the drive cycle and 2 hour idle test.
A quarter-tank of fuel is required to complete the test. Add fuel as required.

2.

If the Service Hybrid System DIC message is displayed at any time, follow service
instructions in SI for the particular DTC or tell tale that is set.

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January 2013

Bulletin No.: 12238C

3.

Change the driver information center to show Power Flow Display or use center console
display.

4.

Set parking brake and place shifter in Neutral position. Increase engine speed to 2,000
RPM.

5.

Run in this mode until battery shown in Power Flow Display is completely filled.

6.

Shift back to Park and release parking brake.

7.

Turn on 12V loads.
 Head lamps on with high beams
 Air conditioning set to 78 oF (25 oC), Eco mode (green snowflake LED), recirc., BiLevel
(foot / floor -- do not want Defrost enabled)
 Cabin blower to high speed
 Radio on, with sound muted.
 Heated seats, if equipped
 Rear defog, it will time out, no need to reinitiate

8.

Allow vehicle to idle for approximately 15 minutes.

9.

Perform drive cycle maintaining high 12V loads and air conditioning settings specified in
Step 7.

10. The drive cycle should contain the following maneuvers.
 Perform at least 10 moderate to heavy accelerations followed by, brake regen events,
with 15% brake apply (light to moderate). Perform these tasks from a vehicle speed of
greater than 30 mph (50 km/h) down to at least 5 mph (8 km/h).
 Perform at least 3 key off / key on cycles with a 2 minute off time, spread out throughout
drive cycle. Note: you will need to turn high beams and heated seats back on after each
key cycle.
11. Return vehicle to dealership (testing continues outside). Set parking brake and place shifter
in Neutral and operate engine at 2,000 RPM until hybrid battery display shows full.

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Bulletin No.: 12238C

12. Place shifter in Park, release parking brake, and allow vehicle to idle for 2 hours with the
following 12V loads on:
 Head lamps with high beams
 Cabin blower on highest setting
 Air conditioning set to 78 deg. F (25 deg. C), Eco mode (green snowflake LED), recirc.,
Bi Level (foot / floor -- do not want Defrost enabled)
 Heated seats on high
 Windows up
 Radio on, with sound muted
 4 way flashers on
 Dome lights on
13. Turn off engine and all 12 V loads, headlamps, dome lamps, and hazard lamps. Wait 2
minutes, then restart engine.
14. If the Service Hybrid System DIC message is displayed at any time, follow service
instructions in SI for the particular DTC or tell tale that is set.
WARRANTY TRANSACTION INFORMATION
Submit a transaction using the table below.
Labor
Code
V2675

Description
Generator Control Module Performance Inspection*
Add: Testing on Replaced Module

Labor
Time
3.0
3.0

Net
Item
**

* Parts, diagnostic time, and repair time, if required, due to DTCs found during the inspection
are to be submitted using normal warranty labor codes.
** Submit the cost of ¼ tank (15 litres) of gasoline required to perform the test in the Net Item
field, not to exceed $16.00 USD, $24.00 CAD per test.
DEALER PROGRAM RESPONSIBILITY
Dealers must take the steps necessary to ensure that the service update correction has been
made to all involved vehicles in dealer inventory before selling or dealer-trading the vehicle, but
no later than October 31, 2013.

GM bulletins are intended for use by professional technicians, NOT a "do-it-yourselfer". They are written to inform these technicians of conditions that
may occur on some vehicles, or to provide information that could assist in the proper service of a vehicle. Properly trained technicians have the tools,
equipment, safety instructions, and know-how to do a job properly and safely. If a condition is described, DO NOT assume that the bulletin applies to
your vehicle, or that your vehicle will have that condition. See your dealer for information on whether your vehicle may benefit from the information.

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