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Service bulletin 34-079

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 id10161055
Published by NHTSA2019-06-10
Manufacturer's number34-079
Manufacturer's date2019-05-21
NHTSA componentPOWER TRAIN

NHTSA's summary

Fix-As-Fail ? Intermittent throttle hesitation may be encountered after installing an optional PTO connector.

The document

The document is the manufacturer's. This site does not hold it. NHTSA files a document at one of these two addresses; we have not asked NHTSA which.

Components

Transmission and driveline

Vehicles listed
KENWORTH T6802019
KENWORTH T8802019
KENWORTH W9902019
PETERBILT 5672019, 2020
PETERBILT 5792019, 2020

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

Recalls for the same vehicles and component
20V5060002020-08-26. POWER TRAIN:AXLE ASSEMBLY
19V9110002019-12-19. POWER TRAIN:AXLE ASSEMBLY:AXLE SHAFT; POWER TRAIN:DRIVELINE:DRIVESHAFT
20187392018-12-24. Powertrain
18V9310002018-12-21. POWER TRAIN:CLUTCH ASSEMBLY

A recall listed here may apply to some of the same vehicles. Only the manufacturer can say whether it applies to one vehicle.

Other bulletins for the same vehicles and component
26-0352026-07-21. Service bulletin. Updated Eaton's TAIB0885EN Bulletin link.
E3112025-09-03. Other. Condition, Chassis Affected, and Warranty sections updated with the following verbiage “E311 must be flagged and open in Service Information Record (SIR) at the time of RO open date to qualify.” Also, “Through Standard Warranty or any applicable active Extended Warranty” verbiage was removed from Warranty section.
T016 / 26-0402025-06-05. Service bulletin. T016: Warranty section updated to include 0.5 hours for test drive. Recommended Repair T016C has been updated from 6.4 hours to 6.9 hours. SRT codes updated in PRWS Claim Coding Table: B25-17A for 6.9 hours created to replace all other codes. 26-040: Warranty section updated to include 0.5 hours for test drive. Recommended Repair 26040C has been updated from 6.4 hours to 6.9 hours. SRT codes updated in PRWS Claim Coding Table: B25-17A for 6.9 hours created to replace all other codes.
7-7002024-11-05. Warranty extension. 7/700 Service Agreement - Letter Only.
45-0652023-10-03. Service bulletin. Certain 579 MLU chassis equipped with Cummins X15 engines have fan hub bracket hardware that are incorrect for the application and/or under torqued and could become loose and/or fail. Procedures are available to replace and properly torque the hardware.
T0122022-01-06. Service bulletin. Non-Safety Campaign: Drivers of vehicles equipped with PACCAR TX-12 transmissions may experience harsh shifts and gear grinding noise. Premature Main Drive Gear damage may occur due to clutch housing and main case countershaft bearing bore wear.
26-0382022-01-06. Service bulletin. Non-Safety Campaign: Eaton Endurant transmissions may experience premature Main Drive Gear damage due to clutch housing and main case countershaft bearing bore wear. A Clutch Housing Front Cover Kit will be installed to address the issue.
21 PBJ2021-10-05. Service bulletin. Safety Recall – Hill Start Assist (HSA) Valve Clearance – NHTSA ID: 21V-648, TC: 2021-521. Crossmember mounted Hill Start Assist valve may not have sufficient clearance to the rear axle, resulting in hose or fitting damage. Damage could cause the loss of rear brake signal, resulting in reduced braking capability and increasing the risk of a crash.
26-0372021-01-06. Service bulletin. Fix-As-Fail - Prior versions of Eaton Endurant transmission software may be prone to setting Linear Clutch Actuator (LCA) fault codes leading to possible LCA hardware replacement.
26-0352021-01-06. Service bulletin. Non-safety campaign: Vehicles equipped with an Eaton Endurant 12 speed transmission may experience transmission service lamp activation, no gear engagement from neutral, and/or DTC 511 FMI 7 or 10 is set. Resolution is to update the transmission software and calibrations.