PIP4379M

Bulletin No.: PIP4379M
Date: Jun-2014
Subject:
Delayed Or No Drive And Or Delayed Or No Reverse With DTCs Range Inhibit
Models:
2007-2015 Chevrolet Silverado
2003-2010 Chevrolet Kodiak
2001-2007 Chevrolet Silverado Classic
2007-2015 GMC Sierra
2003-2010 GMC Topkick
2001-2007 GMC Sierra Classic
Equipped with The Allison LCT1000 Transmission RPO M74 or MW7
This PI was superseded to update Warranty Information field. Please discard PIP4379L.
The following diagnosis might be helpful if the vehicle exhibits the symptom(s) described in this PI.
Condition/Concern
Customer may comment on a delayed or no engagement into drive and or delayed or no engagement into reverse and or a range inhibit with any one of or a
combination of the following DTC's P0701, P0731, P0732, P0733. P0734. P0736, P0751, P0756, P0761, P0776, P0843, P0848, P0873, P0877, P0894 or P2723.
This condition may be more pronounced in cold climates during a cold start.
Recommendation/Instructions
P0701, P0731, P0732, P0733. P0734. P0736, P0751, P0756, P0761, P0776, P0843, P0848, P0873, P0877, P0894 or P2723 could possibly indicate no or
excessively low pump pressure as a result of a no prime or loss of prime condition within the transmission pump. When any of the above DTC's are
accompanied by a P0701 begin troubleshooting with the SI for P0701 first. Be sure to follow all diagnostic steps. With any of the above listed DTC's follow the SI
fluid checking procedure to PROPERLY check the transmission fluid level using the Hot Check Procedure. Low fluid level may cause one of or a combination of
the listed DTC's to set, particularly during a cold ambient and cold vehicle start.
Note: Ensure the fluid level is at the top of the HOT band when the transmission fluid temperature is 175°F. Refer to SI document 2408059 for the proper fluid
level checking procedure.
DTC P0701, P0731, P0732, P0733. P0734. P0736, P0751, P0756, P0761, P0776, P0843, P0848, P0873, P0877, P0894 or P2723 can set by the following: fluid
service/filter change, transmission service involving removing the pan, low fluid level caused by leaks, or after long periods of storage
Note: If the fluid level has been properly checked using the HOT check procedure listed in SI document 2408059 and any of the DTCs reset during a cold start
inspect the internal suction filter for possible cracks
Note: If no other concerns are found inspect for a stuck lube regulator valve (item 13 in document 2384492) in the pump cover due to debris
DTC P0894 diagnostics will run during NLT (neutral lock turbine). During NLT the transmission applies 3, 5 and Reverse clutch and 2, 6 clutch, in conjunction
with Low & Reverse clutch already applied to lock turbine shaft. This feature is only active in combination when engine elevated idle is active to shorten engine
and cab warm up time. This feature is initiated if transmission sump temperature is greater than -25°C (-13°F) and the engine coolant temperature (ECT) is
greater than -40°C (-40°F). If the transmission sump temperature is greater than 60°C (140°F) or the engine coolant temperature is greater than 60°C (140°F),
the NLT feature will terminate.
Important: Replacement of the TCM will not likely correct any of the above DTC's or low main line pressure.
Warranty Information
The correction for this concern may be one of several repairs described above. For vehicles repaired under warranty, please use the appropriate warranty
1
labor operation based on the actual cause and repair.
Please follow this diagnostic or repair process thoroughly and complete each step. If the condition exhibited is resolved without completing every step, the
remaining steps do not need to be performed.
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.
WE SUPPORT VOLUNTARY TECHNICIAN CERTIFICATION
2