Three problems related to engine shut off without warning have been reported for the 2000 Mercury Grand Marquis. The most recently reported issues are listed below. Please also check out the statistics and reliability analysis of the 2000 Mercury Grand Marquis based on all problems reported for the 2000 Grand Marquis.
I believe this issue effects millions of Ford and Mercury vehicles, many of which are taxi, government, and police cars. Apparently, the computer (pcm) that controls the engine can shut the engine down while the vehicle is driving when certain sensors fail (at least 2 known sensors per my research). I found this out at 65 mph, 2 hours from home. I was told by the dealer that there are no new pcms made for my 2000 car, and that I had to rely on a rebuilt after market pcm. The aftermarket seller related that these computers last approximately 10 years. Even if I replace this part, I believe this effectively makes my (and any such) car a risk to drive, as most rebuilt auto parts are created by simply replacing any failed components out of the many components in the assembly of the part, and leaving others still old and worn. When would the other parts fail, and if the car is operating is a high risk unknown. On top of the fact that this creates a spectacular hazard to motorists, I don't think that's fair to consumers. I can demonstrate what this car does, and go over the oem factory manuals where they cite "replace the pcm". Also, why do these sensors fail to a very unsafe condition, have no logic check (such as testing other sensors to see if they concur before an engine shut down) and why can't they be disconnected to allow the engine to keep working till you can get to the repair?.
2000 Mercury Grand Marquis engine shut down causing consumer to lose power brakes and steering. This was caused by a short in spark plug. The short occurred in the spark plug on the #4 cylinder. This confused the power control module with signals it was receiving from the engine and tried to compensate which affected other systems and a sort of chain reaction occurred.
Vehicle was going about 35 mph when all of a sudden it started shaking. Then, lost its traction control, and caused the lights in the dashboard to turn off. This eventually led the engine to shut off, and the driver lost steering. Taken to dealer for a checkup, but the results showed that the cause was undetermined. Car shuddered, followed by engine shut down resulting in loss of power brakes and steering.