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Service bulletin PIT4550

A bulletin is a manufacturer's communication to its dealers, as NHTSA indexes it. The summary is NHTSA's. The document is the manufacturer's: read it at NHTSA. A bulletin is not a recall, and listing a model year does not mean every vehicle of it is concerned.

The communication, as NHTSA indexes it (as of 2026-10-19)
TypeService bulletin
NHTSA id10024634
Published by NHTSA2008-05-01
Manufacturer's numberPIT4550
Manufacturer's date2008-03-01
ReplacesPIT4550A
NHTSA componentPOWER TRAIN:AUTOMATIC TRANSMISSION:CONTROL MODULE (TCM/PCM/TECM)

NHTSA's summary

LOSS OF HIGH SPEED LAN COMMUNICATIONS. *NJ

The document

No address for NHTSA's copy can be built for this communication. Ask the dealer for it by the manufacturer's number.

Components

Transmission and driveline, Automatic transmission, Transmission control module

Vehicles listed
HUMMER H22008

Listing a model year does not mean every vehicle of it is concerned: the document says which.

Other bulletins for the same vehicles and component
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150089004C2021-03-08. Service bulletin. This service bulletin provides technicians with updated information to help identify the differences between what is considered a fluid leak, and what is considered fluid seepage.
1308116001F2020-12-07. Service bulletin. The intent of this technical bulletin is to identify aftermarket ALDL or DLC interface devices as potential sources for causing multiple customer concerns that do not have other diagnostic methods to identify them.
PIP3366C2018-08-20. Service bulletin. This Preliminary information communicates to the dealer technician thatLight Duty Trucks equipped with automatic transmissions and 4 wheel drive may exhibit a condition of grinding/ratcheting type noise when shifting the automatic transmission into park while the transfer case is in 4 wheel drive low (4LO) range. Dealers technician's are advised this condition should be deemed a normal characteristic of 4WD low operation.
09-07-30-018D2018-06-04. Service bulletin. This informational bulletin provides a revision for 09-07-30-018C to add the 2014 model year and update the Labor Operation.
PI0938A2018-05-21. Service bulletin. This preliminary bulletin provides information on what labor operation number to use for various electrical/electronic control issues.
01-07-30-042H2018-05-21. Service bulletin. This information was created to inform the technician that the 2-3 upshift and the 3-2 downshift clunk is caused by the releasing of the 2-4 band and application of the 3-4 clutch assembly during an upshift. Also during a 3-2 downshift, the releasing of the 3-4 clutch during the application of the 2-4 band, can cause torque reversal down the output shaft creating a clunk. This is a normal condition.
1203100022017-12-22. Service bulletin. This informational bulletin provides a description of the proper wheel installation and proper wheel torque techniques used to install wheels onto vehicles