18NA035

File in Section:
Bulletin No.:
Service Bulletin
Date:
18-NA-035
February, 2018
INFORMATION
Subject:
Information on Transmission Will Not Shift in High Gear During Cold Ambient
Temperatures
Engine:
Transmission:
Encore
1.4L (LE2)
6T40 (MNH)
Cruze
(Gen II - B)
1.4L (LE2)
6T35 (MNU)
1.5L (LYX)
6T40 (MNH),
9T45 (M3U)
Malibu
1.5L (LFV)
6T40 (MNH)
Terrain
1.5L (LYX)
9T45 (M3U)
Brand:
Model:
Buick
Chevrolet
GMC
Equinox
Model Year:
from
2018
VIN:
to
from
to
2019
Involved Region or Country
North America, Middle East, South Korea, Africa, Israel, Brazil, Colombia, Ecuador, Chile,
Uruguay, Peru
Condition
Some customers may comment that the transmission will not shift into overdrive range
during cold ambient temperatures.
Information
This condition may be caused by the engine control system detecting conditions that
indicate the freezing of moisture in the charge air cooler.
When the control system detects the above conditions and the ambient temperature is
below 32°F (0°C), it takes the following actions:
• Requests a lower gear than normal (resulting in higher RPM).
• The system will enable the condition as needed to prevent freezing.
⇒ This strategy is to prevent a potential excessive air restriction due to icing
condition which would lead to a P0299 DTC and reduced engine
power mode.
Explain to the customer their vehicle is operating normally. Do not attempt to repair or
replace any parts to alter the original vehicle design intent. You may wish to give the
customer a copy of this bulletin.
Version
2
Modified
Released February 2, 2018
February 12, 2018 - Updated the temperature readings to 32°F (0°C) and removed a
transmission for the Terrain.
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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