Technical Service Bulletin 34-091 — 2021 PETERBILT 579
ELECTRICAL SYSTEM
Bulletin Details
| TSB ID | 34-091 |
| Manufacturer | |
| Vehicle | 2021 PETERBILT 579 |
| Component | ELECTRICAL SYSTEM |
| Communication Date |
Bulletin Summary
Non-Safety Campaign â An incorrectly set VECU software parameter is causing the running lamps to be inactive for certain, US registered, model year 2021 579 chassis. The parameter can be correctly set by reflashing the VECU  with updated software.
About Technical Service Bulletins
A Technical Service Bulletin (TSB) is a document issued by a vehicle manufacturer to its dealers, describing a known issue with a specific vehicle or set of vehicles and the recommended procedure to fix it. Unlike recalls, TSBs are not mandatory and are typically only performed if an owner reports the related issue. However, TSBs can be an indicator of common problems with a vehicle.