21-NA-003

Bulletin No.:
Service Bulletin
Date:
21-NA-003
March, 2024
TECHNICAL
Subject:
Loss of and/or Reduced Propulsion, DTCs P0730, P0746, P0776, P0841, P0846, P0961
and/or P0965 Set
Model Year:
Brand:
Model:
Buick
Encore GX
2020
Malibu
2019
Trailblazer (VIN M)
2021
from
to
VIN:
from
to
Engine:
Transmission:
1.2L (LIH) or
1.3L (L3T)
2024
—
Chevrolet
—
1.5L (LFV) or
1.35L (Korea)
VT40 CVT
Automatic (MRG)
1.2L (LIH) or
1.3L (L3T)
Involved Region or Country
North America, GM Korea Company
Condition
Some customers may comment on loss of and/or reduced propulsion.
Technicians may find one or more of the following DTCs set in the Transmission Control
Module (TCM):
• P0730: Gear Ratio Incorrect
• P0746: Transmission Control Solenoid Valve 1 Stuck Off
• P0776: Transmission Control Solenoid Valve 2 Stuck Off
• P0841: Transmission Fluid Pressure Sensor 1 Performance
• P0846: Transmission Fluid Pressure Sensor 2 Performance
• P0961: Transmission Control Solenoid Valve 1 Performance
• P0965: Transmission Control Solenoid Valve 2 Performance
Cause
Copyright 2024 General Motors LLC. All Rights Reserved.
Note: This condition may be intermittent and not reproducible.
This condition may be caused by the pressure regulator valve sticking in the valve body.
Page 2
March, 2024
Bulletin No.: 21-NA-003
Refer to Service Bulletin# 20-NA-120 to inspect the condition of the chain and pulleys, as
these DTCs can allow slip to happen and cause damage.
• If the chain or pulleys are damaged, the transmission must be replaced.
• If the chain and pulleys are not damaged, continue with correction.
1. Replace the valve body and pressure sensors if the first DTC to set freeze frame
data shows low pressure on primary and/or secondary pulley pressure and has
some or all of these codes set: P0746, P0776, P0841, P0846, P0961, P0965,
P0730.
2. Replace the solenoid body if additional solenoid related codes like P2723 are set in
conjunction with some or all of these codes: P0746, P0776, P0841, P0846, P0961,
P0965, P0730.
⇒ If unable to read primary pulley pressure, primary pulley pressure command,
secondary pulley pressure, secondary pulley pressure command, then
replace the solenoid body, valve body, and sensors.
Correction
Note: Once the Transmission Control Module (TCM) detects stuck or ticking valves,
4000 kpa line pressure is commanded to both pulleys to protect from slip and pulley
damage. When operating in this mode, often all codes (P0746, P0776, P0841, P0846,
P0961, P0965, P0730) will set eventually. The first to set codes are the most relevant to
the initial failure.
⇒ If the condition is not intermittent and before repair, confirm that the main
pump is working correctly and/or there is no pressure loss due to internal
leakage. Reset DTC and monitor pulley pressures. If the transmission is still
reporting an under-pressure condition, further diagnostics will be needed to
look for internal leaks, low fluid level, and pump operation.
⇒ If the condition has additional sensor related codes, further diagnostics will
be needed to look for wire harness issues and/or sensor issues. If the
transmission loses the ability to correctly control ratio (for example a speed
sensor fails), these codes: P0746, P0776, P0841, P0846, P0961, P0965,
P0730 can also set as the control system reacts by commanding 4000 kpa to
pulleys.
Important: Service agents must comply with all
International, Federal, State, Provincial, and/or
Local laws applicable to the activities it performs
under this bulletin, including but not limited to
handling, deploying, preparing, classifying,
packaging, marking, labeling, and shipping
dangerous goods. In the event of a conflict between
the procedures set forth in this bulletin and the
laws that apply to your dealership, you must follow
those applicable laws.
Service Information
Refer to Control Valve Body Replacement in the
Service Manual and Automatic Transmission Fluid
Pressure Sensor Replacement in the Service Manual.
If required, refer to Control Valve Solenoid Body
Replacement in the Service Manual.
Parts Information
Causal
Part
Description
Part
Number
Qty
X
BODY, C/VLV
24042059
1
X
SENSOR, A/
TRNS FLUID
PRESS
24295253
2
X
BODY, C/
VLV SOL
24288570
1
N/A
SEAL, C/VLV
CVR WRG
CONN HOLE
24280824
1
N/A
SEAL, A/TRNS
FLUID LVL
CONT VLV
24292808
1
N/A
PLUG, A/TRNS
FLUID
TEMP SEN
24285336
1
N/A
FLUID, TRNS
Refer
to EPC
As Required
Bulletin No.: 21-NA-003
March, 2024
Page 3
Warranty Information
Note: Only use the Labor Operation number that
coincides with the repair performed.
For vehicles repaired under warranty, use:
Labor
Operation
Description
Labor Time
8463690
Control Valve Body
Replacement
8462540
Automatic Transmission
Fluid Pressure Sensor
Replacement
8463700
Control Valve Solenoid Body
Use
Published
Labor
Operation
Time
Version
4
Modified
Released July 16, 2021
Revised May 11, 2022 — Removed 2020 Trailblazer.
Revised July 01, 2022 - Added 2022 and 2023 Model Years.
Revised February 26, Added 2024 Model Year and Removed 24277045 from Parts
Information section.
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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