1999 GMC C6500 problems

Defect

CERTAIN MEDIUM DUTY C-SERIES AND B7 SCHOOL BUS CHASSIS EQUIPPED WITH A 7.4 LITER GAS ENGINE AND AN IMPCO LPG CONVERSION KIT. SOME OF THESE VEHICLES MAY HAVE ENGINE BACKFIRES WITH SUFFICIENT FORCE TO DAMAGE THE ENGINE AIR INTAKE SYSTEM AND THE AIR CLEANER FILTER ELEMENT.

Consequence

IF THE DAMAGED AIR CLEANER PARTS ARE DISLODGED FROM THEIR NORMAL POSITION, THESE PARTS COULD COME IN CONTACT WITH THE HOT EXHAUST MANIFOLD AND/OR HOT EXHAUST GAS RECIRCULATION (EGR) VALVE TUBE RESULTING IN A POSSIBLE ENGINE COMPARTMENT FIRE.

Remedy

DEALERS WILL INSTALL A REDESIGNED MIXER BONNET AND AIR CLEANER HOUSING COVER, SELECTIVE UPGRADES IN VARIOUS CONNECTIONS RELATED TO THE AIR INDUCTION SYSTEM, AND IF NEEDED, A NEW AIR CLEANER FILTER. OWNER NOTIFICATION BEGAN DECEMBER 18, 2002. OWNERS WHO TAKE THEIR VEHICLES TO AN AUTHORIZED DEALER ON AN AGREED UPON SERVICE DATE AND DO NOT RECEIVE THE FREE REMEDY WITHIN A REASONABLE TIME SHOULD CONTACT CHEVROLET AT 1-800-222-1020 OR GMC AT 1-800-462-8782.

Defect

VEHICLE DESCRIPTION: SCHOOL BUSES, MEDIUM DUTY TRUCKS AND TRACTORS BUILT WITH BENDIX AIR ABS WITH AN EC-17 1030R ELECTRONIC CONTROL UNIT (ECU), THERE HAVE BEEN REPORTS OF UNWANTED ABS ACTIVATION AT LOW SPEEDS CAUSED BY 1) CHAFED ABS WHEEL SPEED SENSOR WIRES ON ROTATING PARTS OR 2) A DAMAGED COMPONENT AT THE WHEEL END THAT GENERATES A CERTAIN TYPE OF ERRATIC SENSOR SIGNAL.

Consequence

THIS CONDITION COULD CAUSE THE ABS ECU TO EXHAUST THE AIR AT THE AIR BRAKE MODULATORS FOR ONE OR MORE OF THE WHEELS. THIS COULD RESULT IN EXTENDED BRAKING DISTANCES AND A POSSIBLE CRASH.

Remedy

DEALERS WILL REPLACE THE ABS ECU.

Defect

VEHICLE DESCRIPTION: MEDIUM DUTY TRUCKS. THE TRANSMISSION FLUID COULD LEAK FROM A HEAT DEGRADED TRANSMISSION FLUID COOLER HOSE ONTO THE EXHAUST SYSTEM ON THE PASSENGER'S SIDE OF THE VEHICLE.

Consequence

THIS CONDITION COULD RESULT IN A FIRE.

Remedy

DEALERS WILL INSTALL A NEW TRANSMISSION FLUID COOLER INLET HOSE AND OUTLET HOSE DESIGNED WITH A HEAT SLEEVE AND ENSURE ADEQUATE CLEARANCE TO THE EXHAUST SYSTEM TAKE-DOWN PIPE. DEALERS WILL ALSO INSPECT THE RIGHT-HAND EXHAUST MANIFOLD SEAL FOR LEAKAGE, AND REPLACE IF NECESSARY.

Defect

VEHICLE DESCRIPTION: MEDIUM DUTY CONVENTIONAL CAB TRUCKS AND SCHOOL BUS CHASSIS EQUIPPED WITH AN AUTOMATIC TRANSMISSION, HAVE TRANSMISSION SHIFT CABLE END RODS THAT HAVE NOT BEEN CRIMPED TO THE PROPER SPECIFICATION. OVER TIME, THE SHIFT CABLE COULD BE PULLED OUT OF THE ROD END CAUSING THE DRIVER TO LOSE THE ABILITY TO MANUALLY CHANGE TRANSMISSION GEARS.

Consequence

WITH THIS CONDITION, THE VEHICLE MAY MOVE IN A DIRECTION NOT ANTICIPATED BY THE DRIVER, INCREASING THE RISK OF A CRASH.

Remedy

DEALERS WILL INSTALL A NEW SHIFT CABLE.