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Service bulletins for the 2020 Western Star 4900

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.

156 on file from NHTSA, as of 2026-10-19.

By type

By component

Only bulletins with component: Electrical system are shown. Show all

Bulletins, newest first
CALWS83-0012021-09-29. Service bulletin. ELECTRICAL SYSTEM; VISIBILITY. Customer Advisory Letter for HVAC Actuator Wiring Harness. The wiring harness of the actuator of the fresh air recirculation door, shown in Fig. 1, on Western Star vehicles equipped with Red Dot HVAC systems should be inspected for signs of water intrusion and corrosion.
SBW54-0802021-06-29. Service bulletin. ELECTRICAL SYSTEM. Western Star Service Bulletin for Key Fob ID Retention. Key fobs for remote keyless entry on Western Star vehicles are delivered in packages that include a unique ID for the fob. The ID is required when pairing the key fob with a vehicle.
SS708-WST20212021-06-26. Service bulletin. ELECTRICAL SYSTEM. Western Star Service Solution for Low Voltage Disconnect (LVD) Troubleshooting: Western Star 5700 and New 4700.
SBW54-0572021-03-25. Service bulletin. EQUIPMENT; ELECTRICAL SYSTEM. Western Star Service Bulletin for Powernet Troubleshooting Guide - Batteries, Path, Alternator, and Starter. When troubleshooting powernet issues, use the BCT-460DTNA PowerNet Assessment Tool. As of May 29, 2018, the AutoMeter is the only Daimler-approved tool for troubleshooting vehicle Powernet issues.
WP21-0072021-03-24. Service bulletin. EQUIPMENT; ELECTRICAL SYSTEM. Warranty Policy Letter for battery tags. DTNA determined that since adopting the AutoMeter BCT-460DTNA Powernet Assessment Tool (AutoMeter) as the required powernet system tester, not all battery tags have to be retained support Warranty-related claims.
WI21-0062021-02-26. Service bulletin. ELECTRICAL SYSTEM; ENGINE AND ENGINE COOLING; EQUIPMENT ADAPTIVE/MOBILITY; EQUIPMENT. Warranty Information Letter for Detroit NOx Sensor Circuit Fault Codes - Claim Guidelines.
TechTalk76982020-11-03. Service bulletin. EXTERIOR LIGHTING:BRAKE LIGHTS; ELECTRICAL SYSTEM. Tech Talk discussion on dim brake lights on 2020 western star.
20TS-072020-10-21. Service bulletin. ELECTRICAL SYSTEM:SOFTWARE; POWER TRAIN:AUTOMATIC TRANSMISSION:CONTROL MODULE (TCM/PCM/TECM); ENGINE AND ENGINE COOLING. Technical Service Letter for Cold Weather Faults on GHG17/21 DD13 with MCM Software Version 14. Due to colder weather, there may be an increase in the frequency of faults, noted below, on GHG17/21 DD13 trucks built after June 5th 2019. This is due to a calibration issue in the current MCM software (14.1.1.5 or 14.2.1.3). New software is scheduled for release in the first quarter of 2021 that will address these faults.
17TS-05REV22020-10-21. Service bulletin. POWER TRAIN; ELECTRICAL SYSTEM:SOFTWARE. Revised Technical Service Letter for Detroit DT12 TCM GHG17 Only; Bootloader Update. On Detroit DT12 equipped vehicles, it may be necessary to complete an additional step in the programming process when updating the TCM software.
20CSA-152020-09-02. Service bulletin. ELECTRICAL SYSTEM; ENGINE AND ENGINE COOLING; EQUIPMENT. Customer Service Announcement for Release of DiagnosticLink 8.12 Service Pack 2. On Thursday, September 3, 2020, Service Pack (SP) 2 for DiagnosticLink 8.12 Standard and Professional will be made available to download from the Detroit Diesel server.
SBW54-0752020-04-18. Service bulletin. ELECTRICAL SYSTEM; BACK OVER PREVENTION. Service Bulletin for Lengthening the Backup Light Harness. Though the back-up light harness is long enough to connect to the backup light switch, it may be short enough that the wire seals in the connector can be stressed. Moisture entering through the seals can cause corrosion, resulting in a bad connection and/or failure of the switch. As a result, backup lights and, if equipped, the backup alarm, may not function when the vehicle is shifted into reverse.
20CSA-032020-03-06. Service bulletin. ELECTRICAL SYSTEM:SOFTWARE. Customer Service Announcement saying that Service Pack (SP) 2 for Diagnostic Link 8.11 Standard and Professional will be available for download from the Detroit Diesel server.
SS10341792020-02-20. Service bulletin. ELECTRICAL SYSTEM; EQUIPMENT. Service Solution on Western Star speedometers. For certain speedometers the speedometer may drop out or the odometer may reset to zero.
SBW54-0612020-02-15. Service bulletin. ELECTRICAL SYSTEM. Service Bulletin for Guidelines for Repairing or Replacing an Electrical Harness. Use the guidelines in this bulletin to determine if a damaged electrical harness should be repaired or replaced.
20CSA-022020-02-01. Service bulletin. ELECTRICAL SYSTEM; ENGINE AND ENGINE COOLING. Customer Service Announcement reminding service locations to update their DiagnosticLink software. To maintain access to the Detroit server, all DiagnosticLink computers must be updated with the current version of DiagnosticLink software. all DiagnosticLink 8.08 installed versions will be disabled as of Tuesday, January 28, 2020.
17TS-12REV2020-01-03. Service bulletin. ELECTRICAL SYSTEM:WIRING; ENGINE AND ENGINE COOLING; EQUIPMENT ADAPTIVE/MOBILITY; EQUIPMENT. Technical Service Letter for GHG17 Heavy Duty Engine Platform 1-BOX Aftertreatment System (ATS) Wire Harness experiencing chaffing caused by vibration and dirt collecting in the harness conduit.
WI19-0222020-01-02. Service bulletin. ENGINE AND ENGINE COOLING; EQUIPMENT; ELECTRICAL SYSTEM. Warranty Information Letter announcing Detroit NOx Sensor Circuit Improvements for GHG17 After Treatment Systems
SS10344992019-10-30. Service bulletin. EQUIPMENT; ELECTRICAL SYSTEM. Service Solution on failing RX modules in Western Star vehicles.
19TL-202019-10-26. Service bulletin. ELECTRICAL SYSTEM; EQUIPMENT. Tool Letter for DAVCO Shop Pro FXP 95-230V compatible for Australia Electrical Systems.
19TL-192019-10-26. Service bulletin. ELECTRICAL SYSTEM; EQUIPMENT. Tool Letter for DAVCO Shop Pro FXP 95-230V compatible for Chile and Italy Electrical Systems
SBW54-0732019-09-28. Service bulletin. ELECTRICAL SYSTEM. Service Bulletin for Powernet Distribution Box Functional Changes

The summaries are NHTSA's. Each bulletin's page links NHTSA's copy of the manufacturer's document.