Most likely under the hood of the car in the black fuse panel box. But first check your book that comes with the car to rule out the panel box under near drivers left knee.
On a 1999 Mercury Sable : Relay # 30 is the Powertrain Control Module ( PCM ) relay
What is a gem module for 1999 mercury sable? And what does it control?
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PCM stands for Powertrain Control Module on a Mercury Sable
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 2003 Mercury Sable : In the Power Distribution Box ( which is " live " ) located in the front of the engine compartment by the battery ( # 30 is the fuel pump relay ) Also , # 16 is a 20 amp mini fuse for the fuel pump relay
location for fuse, and relay switch on a Mercury Sable
In the relay block with the other relays.
where is the horn relay on my 1993 Mercury Sable located
The horn relay for a 1998 Sable is on the back of the distribution block. The block is under the dash on the drivers side.
You can find the wiring diagram for a relay position for a 1997 Mercury Sable in the owner's manual. You can also check local auto stores.