20NA176

Bulletin No.:
Service Bulletin
Date:
20-NA-176
September, 2020
TECHNICAL
Subject:
Brand:
Chevrolet
GMC
Malfunction Indicator Lamp (MIL) Illuminated - DTCs P1338, P1339, P133A, P133B,
P133C, P133D, P133E, P133E, P133F, P066A, P066B, P066C, P066D, P066E, P066F,
P0671, P0672, P0673, P0674, P0675, P0676, P0677, P0678, P067A, P067B, P067C,
P067D, P067E and/or P067F Set
Model:
Model Year:
from
to
Silverado
2017
2018
Silverado 2500HD/
3500HD
2017
2019
Silverado 4500HD/
5500HD/6500HD
2019
2020
Sierra
2017
2018
Sierra 2500HD/
3500HD
2017
2019
VIN:
from
to
-
-
Engine:
Transmission:
L5D, L5P
-
Involved Region or Country
United States, Canada, Middle East, Palestine and Israel
Condition
Some customers may comment that the MIL is illuminated.
Some technicians may find one or more of the following DTCs set in the Engine Control
Module (ECM):
• DTC P066A: Cylinder 1 Glow Plug Control Circuit Low Voltage
• DTC P066B: Cylinder 1 Glow Plug Control Circuit High Voltage
• DTC P066C: Cylinder 2 Glow Plug Control Circuit Low Voltage
• DTC P066D: Cylinder 2 Glow Plug Control Circuit High Voltage
• DTC P066E: Cylinder 3 Glow Plug Control Circuit Low Voltage
• DTC P066F: Cylinder 3 Glow Plug Control Circuit High Voltage
• DTC P0671: Cylinder 1 Glow Plug Control Circuit
• DTC P0672: Cylinder 2 Glow Plug Control Circuit
• DTC P0673: Cylinder 3 Glow Plug Control Circuit
• DTC P0674: Cylinder 4 Glow Plug Control Circuit
• DTC P0675: Cylinder 5 Glow Plug Control Circuit
• DTC P0676: Cylinder 6 Glow Plug Control Circuit
• DTC P0677: Cylinder 7 Glow Plug Control Circuit
• DTC P0678: Cylinder 8 Glow Plug Control Circuit
• DTC P1338: Cylinder 1 Glow Plug Offset Exceeded Learning Limit
• DTC P1339: Cylinder 2 Glow Plug Offset Exceeded Learning Limit
• DTC P133A: Cylinder 3 Glow Plug Offset Exceeded Learning Limit
• DTC P133B: Cylinder 4 Glow Plug Offset Exceeded Learning Limit
• DTC P133C: Cylinder 5 Glow Plug Offset Exceeded Learning Limit
• DTC P133D: Cylinder 6 Glow Plug Offset Exceeded Learning Limit
• DTC P133E: Cylinder 7 Glow Plug Offset Exceeded Learning Limit
• DTC P133F: Cylinder 8 Glow Plug Offset Exceeded Learning Limit
Cause
The cause of the condition may be a software anomaly.
Correction
Reprogram the Glow Plug Control Module (GPCM) with the latest available software.
Copyright 2020 General Motors LLC. All Rights Reserved.
Page 2
September, 2020
Bulletin No.: 20-NA-176
Service Procedure
Caution: Before downloading the update files, be sure
the computer is connected to the internet through a
network cable (hardwired). DO NOT DOWNLOAD or
install the files wirelessly. If there is an interruption
during programming, programming failure or control
module damage may occur.
Note: Carefully read and follow the instructions below.
•
•
•
•
Ensure the programming tool is equipped with the
latest software and is securely connected to the
data link connector. If there is an interruption
during programming, programming failure or
control module damage may occur.
Stable battery voltage is critical during
programming. Any fluctuation, spiking, over
voltage or loss of voltage will interrupt
programming. Install a GM Authorized
Programming Support Tool to maintain system
voltage. Refer to www.gmdesolutions.com for
further information. If not available, connect a fully
charged 12 V jumper or booster pack
disconnected from the AC voltage supply. DO
NOT connect a battery charger.
Turn OFF or disable systems that may put a load
on the vehicles battery such as; interior lights,
exterior lights (including daytime running lights),
HVAC, radio, etc.
Clear DTCs after programming is complete.
Clearing powertrain DTCs will set the Inspection/
Maintenance (I/M) system status indicators to NO.
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Bulletin No.: 20-NA-176
September, 2020
Page 3
5431207
Important: Techline Connect and TIS2WEB screens
shown above.
Important: If the Same Calibration/Software Warning
is noted on the TLC or SPS Summary screen, select
OK and follow screen instructions. After a successful
programming event, the WCC is located in the Service
Programming System dialogue box of the SPS
Summary screen. No further action is required. Refer to
the Warranty section of the bulletin.
Important: When programming a module in GM’s new
Vehicle Intelligence Platform, or VIP, the power mode
(ignition) needs to be off or errors may occur. This
involves the 2020 Chevrolet Corvette, Cadillac CT5 and
CT4, as well as the upcoming full-size Chevrolet, GMC,
Cadillac SUVs and Buick Envision. Serial Data
Message Authentication also needs to have the
ignition off.
1. Reprogram the Glow Plug Control Module. Refer to
K34 Glow Plug Control Module: Programming and
Setup in SI.
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September, 2020
Bulletin No.: 20-NA-176
5644478
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Bulletin No.: 20-NA-176
September, 2020
Page 5
Important: To avoid warranty transaction rejections,
you MUST record the warranty claim code provided on
the SPS Warranty Claim Code (WCC) screen shown
above on the job card. Refer to callout 1 above for the
location of the WCC on the SPS screen
2. Record SPS Warranty Claim Code on job card for
warranty transaction submission.
Parts Information
No parts are required for this repair.
Warranty Information
For vehicles repaired under warranty, use:
Labor Operation
Description
Labor Time
*2810055
Glow Plug Control Module Reprogramming with SPS
Use Published Labor
Operation Time
Important: *To avoid warranty transaction rejections, carefully read and follow the instructions below:
• The SPS Warranty Claim Code must be accurately entered in the “SPS Warranty Claim Code” field of the transaction.
• When more than one Warranty Claim Code is generated for a programming event, it is required to document all Warranty
Claim Codes in the “Correction” field on the job card. Dealers must also enter one of the codes in the “SPS Warranty Claim
Code” field of the transaction, otherwise the transaction will reject. It is best practice to enter the FINAL code provided
by SPS.
Warranty Claim Code Information Retrieval
If the SPS Warranty Claim Code was not recorded on
the Job Card, the code can be retrieved in the SPS
system as follows:
1. Open TIS on the computer used to program the
vehicle.
2. Select and start SPS.
3. Select Settings.
4. Select the Warranty Claim Code tab.
The VIN, Warranty Claim Code and Date/Time will be
listed on a roster of recent programming events. If the
code is retrievable, dealers should resubmit the
transaction making sure to include the code in the SPS
Warranty Claim Code field.
Version
1
Modified
Released September 03, 2020
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 equipment, tools, 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 GM dealer for information on whether your vehicle may benefit from the
information.
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