Three problems related to cruise control have been reported for the 2003 Mercury Grand Marquis. The most recently reported issues are listed below. Please also check out the statistics and reliability analysis of the 2003 Mercury Grand Marquis based on all problems reported for the 2003 Grand Marquis.
The engine revved in full throttle when the gear shifter was shifted into drive from park; resulting in a rear end collision. This occurred while in stop and go traffic in the car wash line. The repair shop failed to determined what caused the failure, but the consumer feels due through their own research that it was caused by the electrical system/cruise control.
: the contact stated while parked with the ignition on; the vehicle suddenly lurched forward without warning. The brakes were depressed and the ignition was turned off, which stopped the vehicle after it traveled 60 ft. This had occurred on numerous occasions. Also, while traveling 60 mph with the cruise control engaged, the vehicle sped uncontrollably to 80 mph. The brakes were depressed, but did not disengage the cruise control. Also, while traveling 40 mph, the vehicle accelerated suddenly, causing the contact to drive the vehicle into a ditch to avoid an accident. The contact sustained a bruise to the shoulder. The manufacturer was contacted, and provided no assistance since the vehicle was out of warranty. The vehicle was taken to a service dealer twice, where the cruise control was replaced, but the problem persisted.
While driving under raining conditions cruise control was not working. Instrument lights panel was off, and windshield worked intermittently. Dealer replaced two computers in the electrical system , but problem still occurring.