It controls the variable Power Steering on your vehicle. The faster the car goes the less power steering the vehicle needs. The module is what controls that. It senses the cars speed and then determines how much power steering "power" needs to be applied.
What is a gem module for 1999 mercury sable? And what does it control?
The GEM is $1200.00 plus labor. Better ideas by Ford
Where is ignition control module on a 2001 mercury sable
PCM stands for Powertrain Control Module on a Mercury Sable
The best way to troubleshoot your GEM module on your Mercury is with a diagnostic tester. The diagnostic tester will tell you if the module is working properly.
The 1999 Mercury Sable computer module can be located behind the passenger side dashboard. The dashboard will need to be removed in order to view the computer module.
On a 1999 Mercury Sable : Relay # 30 is the Powertrain Control Module ( PCM ) relay
behind the radio, to the left
Replace auto lamp module.
On the top of firewall on passenger side of engine bay.
The wiper control module is mounted on a bracket near the steering column support bracket.
What do you mean by "gem"?