1991 Porsche 911 Service and Repair Manual

A PART OF THE STEERING COLUMN UPPER UNIVERSAL JOINT CRACKED DURING THE MANUFACTURING PROCESS.

THIS CONDITION COULD RESULT IN NOISE AND FREE PLAY IN THE STEERING SYSTEM AND IF LEFT UNCORRECTED, W

DEALERS WILL INSPECT THE UNIVERSAL JOINT FOR CRACKS AND WILL REPLACE CRACKED JOINTS WITH NEW PARTS.

THE HYDRAULIC BRAKE PRESSURE REDUCTION VALVE CAUSES THE RATE OF HYDRAULIC PRESSURE REDUCTION TO SLOW DOWN, WHICH MAY RESULT IN THE REAR WHEELS LOCKING-UP EVEN WITH THE ANTI-LOCK BRAKE SYSTEM IN OPERAT

REAR WHEEL LOCK-UP MAY RESULT IN LOSS OF VEHICLECONTROL AND AN ACCIDENT.

PORSCHE DEALERS WILL INSTALL A MODIFIED HYDRAULIC BRAKE PRESSURE REDUCTION VALVE.

AFTER THE ENGINE HAS BEEN TURNED OFF, THE REAR HEATER WILL AUTOMATICALLY OPERATE IN ORDER TO DISSIPATE HEAT IN THE ENGINE HEATING SYSTEM. DURING THIS OPERATION, THE RESISTOR FOR THE REAR HEATER BLOWER

THE OVERLOADED RESISTOR CAN CREATE HEAT SUFFICIENT TOIGNITE THE PLASTIC AIR PIPE TO WHICH IT IS CONN

PORSCHE DEALERS WILL INSTALL A NEW RESISTOR CONTAINING A CIRCUIT BREAKER.

THE BALL SOCKETS ON THE CRUISE CONTROL LINKAGE CAN BREAK, ALLOWING THE CRUISE CONTROL LINKAGE TO BECOME DETACHED ON ONE END AND JAM ON NEARBY COMPONENTS, WHICH COULD IMPAIR THROTTLE PLATE OPERATION.

IMPAIRED THROTTLE PLATE OPERATION COULD PREVENT THEENGINE FROM RETURNING TO IDLE, RESULTING IN UNWAN

REPLACE THE CURRENT PLASTIC BALL SOCKETS WITH A NEW LINKAGE USING STEEL BALL SOCKETS, AND LUBRICATE