2009 mercury grand marquis horn not working

SOURCE: rear shocks on a 1996 Mercury Grand Marquis

Raise car under frame then put jack under axle before removing the shock.
Can use locking pliers to hold the shaft from turning (may have to cut away dust boots). Top nuts are accessed and can be seen from the wheel wells or from the gap between the trunk and mount frame (can't see nut from this angle). Take care with fuel lines near the driver side nut.
Preventing shafts from turning on new shocks will be tough. Make sure you have a proper tool to fit top of shaft with enough room between top of shaft and trunk (gap decreases as the nut is tightened) so the tool can be removed.

SOURCE: 2000 mercury grand marquis air conditioning won't work

1st Thing,
Located Someone With a Set Of A/C Gauges 134A Freon,
Make Sure Your A/C System Has Enought Freon In It, There Is a Low Freon Pressure Switch
In The Electrical System, Usually, 50-60 PSIG or Less On The Gauges, Will Indicate Low Freon, When Freon Is Low The Compressor Is Dis-engaged To Prevent Compressor Damage.
1] Low Freon
2] Bad Low Pressure switch
3] Blowen Fuse[s]
4] Electrical Problem[s]
[a] Digital Climate Controlled ?
Climate Control Self Diagnose From Button's On Unit, OEM Manual Explains This,
If Yor Auto Has Digital Climate Control.
5] Bad Compressor DC Coil

Note: Does The Compressor Engage, Click-On When Button Is Pressed, But Getting
Only Warm Air?
Is One Of The Compressor Aluminum Tube's Cold, Be Careful Other Is Really Warm/Hot,
If Cold and or Sweating, Dripping Water [Normal], You Are Blending Hot Air w/Cold
Air At The Heater Blend Box, Making Warm Air.
If This Is So, If A Vaccum Controlled Temp Unit, Check For A Vaccum Hose Bad,
Should Be Either 1or 2 Vaccum Lines Going Into Firewall To Feed The Controller
Unit, If OK, Might Be a Bad Blend Box Diaphram, [Control's A/C air, Blocks Off
heater Coil Hot Air].
If Your Auto Is Vaccum Controlled, Can You Changed From Bottom, Dash,
Defrost Air Flow?, Yes, No Vaccum Lost Feeding Controller, Still Might Have
Bad Diaphram Blending Hot Air w/Cold If Your Have Cold Alum-Tubing In
engine Compartment.
If Digital Climate Controlled, Might have Diaphram's, Vaccum Controlled or
electrical Servo's Controlled vs Diaphram [Vaccum] Controlled.
This Might Help, Hopefully, This Is Just For Starter's, There More To Some System's
and Without The OEM Mgr's Manual[s] You/Be Would Be Lost, especially w/Electrical.
Later, God Bless

SOURCE: where are the spark plugs located on a 2000 Mercury Grand Marquis

There are eight COPs (coil-on-plugs) to remove. Using a 7mm or 9/32" socket, remove each bolt securing each COP to the intake manifold on top of the engine. Remove all eight COPs, and the spark plugs are underneath. When replacing the spark plugs, use only the proper Ford/Motorcraft plugs, even if they cost twice as much as the aftermarket ones. You will avoid further headaches this way. Hope this helps.

SOURCE: how to replace starter +1993 Mercury Grand Marquis

disconnect battery,,jack car up,,put jack stand on frame,,take starter bolts out,(may not be easy),,take wires off starter,,hoped it helped,,

SOURCE: 2000 mercury grand marquis horn doesn't work.

The horn is in the very front behind the grille on the drivers side. Eiher the horn is bad or disconnected or the switch in the steering wheel is bad.

Testimonial: "Thank you. I asssumed that the problem was between the relay socket and the horn. You told me the horn location and I found the cable unplugged."