TSB: MACK CHN, CHU, CT, CTP, CV, CXN, CXP, CXU, GU, LEU, MRU (2004–2007)

Bulletin SC-334 — January 11, 2008

Bulletin Details

Bulletin IDSC-334
ManufacturerMACK
ModelsCHN, CHU, CT, CTP, CV, CXN, CXP, CXU, GU, LEU, MRU
Model Years2004–2007
Date IssuedJanuary 11, 2008
Date Added to NHTSAMarch 3, 2010
ComponentSERVICE BRAKES, AIR:SUPPLY:CHECK VALVE
Vehicles Affected19 combinations

What is a TSB?

A Technical Service Bulletin is a document issued by the vehicle manufacturer to inform dealership technicians about a known issue and the recommended repair procedure. TSBs are not mandatory recalls — they serve as repair guidance for common problems.

If your vehicle has this issue, bring this bulletin ID to your dealer. If under warranty, the repair should be covered at no cost.

Summary

MACK TRUCK: IT HAS BEEN DETERMINED THAT THE 90 DEGREE SINGLE CHECK VALVE FITTING MANUFACTURED BY PARKER HANNIFIN CORP. WHICH IS USED IN THE SUPPLY PORT OF THE SPRING BRAKE MODULATING RELAY VALVE (BENDIX SR 7 VALVE) MAY HAVE A DEFECT WHEREB

Affected Vehicles

MakeModelYearComponent
MACK CHN 2007 042300 SERVICE BRAKES, AIR:SUPPLY:CHECK VALVE
MACK CHU 2007 042300 SERVICE BRAKES, AIR:SUPPLY:CHECK VALVE
MACK CT 2007 042300 SERVICE BRAKES, AIR:SUPPLY:CHECK VALVE
MACK CTP 2007 042300 SERVICE BRAKES, AIR:SUPPLY:CHECK VALVE
MACK CV 2007 042300 SERVICE BRAKES, AIR:SUPPLY:CHECK VALVE
MACK CXN 2007 042300 SERVICE BRAKES, AIR:SUPPLY:CHECK VALVE
MACK CXP 2007 042300 SERVICE BRAKES, AIR:SUPPLY:CHECK VALVE
MACK CXU 2007 042300 SERVICE BRAKES, AIR:SUPPLY:CHECK VALVE
MACK GU 2007 042300 SERVICE BRAKES, AIR:SUPPLY:CHECK VALVE
MACK LEU 2007 042300 SERVICE BRAKES, AIR:SUPPLY:CHECK VALVE
MACK MRU 2007 042300 SERVICE BRAKES, AIR:SUPPLY:CHECK VALVE
MACK CHN 2005 042300 SERVICE BRAKES, AIR:SUPPLY:CHECK VALVE
MACK CT 2005 042300 SERVICE BRAKES, AIR:SUPPLY:CHECK VALVE
MACK CV 2005 042300 SERVICE BRAKES, AIR:SUPPLY:CHECK VALVE
MACK CXN 2005 042300 SERVICE BRAKES, AIR:SUPPLY:CHECK VALVE
MACK CHN 2004 042300 SERVICE BRAKES, AIR:SUPPLY:CHECK VALVE
MACK CT 2004 042300 SERVICE BRAKES, AIR:SUPPLY:CHECK VALVE
MACK CV 2004 042300 SERVICE BRAKES, AIR:SUPPLY:CHECK VALVE
MACK CXN 2004 042300 SERVICE BRAKES, AIR:SUPPLY:CHECK VALVE

Related MACK Recalls

CampaignModelYearComponentSummary
ANTHEM AN (4) 2026 SERVICE BRAKES, AIR:ANTILOCK:CONTROL ... Mack Trucks, Inc. (Mack) is recalling certain 2025-2027 Pioneer (4) and 2026-...
ANTHEM AN (4) 2027 SERVICE BRAKES, AIR:ANTILOCK:CONTROL ... Mack Trucks, Inc. (Mack) is recalling certain 2025-2027 Pioneer (4) and 2026-...
PIONEER PR (4) 2025 SERVICE BRAKES, AIR:ANTILOCK:CONTROL ... Mack Trucks, Inc. (Mack) is recalling certain 2025-2027 Pioneer (4) and 2026-...
PIONEER PR (4) 2026 SERVICE BRAKES, AIR:ANTILOCK:CONTROL ... Mack Trucks, Inc. (Mack) is recalling certain 2025-2027 Pioneer (4) and 2026-...
PIONEER PR (4) 2027 SERVICE BRAKES, AIR:ANTILOCK:CONTROL ... Mack Trucks, Inc. (Mack) is recalling certain 2025-2027 Pioneer (4) and 2026-...

What Should You Do?

If your vehicle is affected by this TSB, contact your authorized MACK dealer. Bring this bulletin ID (SC-334) when you visit. If under warranty, the repair should be free. If your warranty has expired, ask about goodwill coverage — manufacturers sometimes cover TSB-related repairs beyond the warranty period.

Frequently Asked Questions

A recall is a mandatory safety fix — the manufacturer must repair every affected vehicle for free. A TSB is an advisory document that describes a known issue and the recommended fix, but repairs are not required. However, some TSBs eventually lead to recalls if the issue poses a safety risk. TSBs are generally issued for quality or performance problems, while recalls address safety defects.

If your vehicle is still under the manufacturer's warranty, TSB-related repairs are typically covered at no cost. If your warranty has expired, you can ask the dealer about goodwill or customer assistance programs. Many manufacturers will cover or partially cover repairs for well-known issues, especially if the TSB was issued recently or affects a large number of vehicles.

Check the make, model, and model year listed above against your vehicle. If they match, this bulletin likely applies. However, TSBs may only affect vehicles with specific production dates, VIN ranges, or configurations. Your dealer can confirm by entering your VIN into their service system, which will show all applicable TSBs and recalls.

This data comes from the National Highway Traffic Safety Administration (NHTSA). Manufacturers are required to submit copies of all communications (including TSBs) sent to their dealers to NHTSA. The agency makes this data publicly available as part of its vehicle safety monitoring program.