The speed control light does not come on and the speed control does not work.

There are several possible reasons why your cruise control may have stopped working. Here are some steps you can take to diagnose the issue:

1. Check the cruise control fuse: The first thing to check is the fuse that controls the cruise control system. Refer to your vehicle's owner manual to locate the fuse box and find the specific fuse for the cruise control. If the fuse is blown, replace it with a new one.
2. Check the brake light switch: The cruise control system is designed to disengage when you step on the brake pedal. If the brake light switch is faulty, the cruise control system may not work. You can test the switch by pressing the brake pedal and checking if the brake lights come on. If the brake lights don't come on, you may need to replace the brake light switch.
3. Check the speed sensor: The speed sensor is responsible for detecting the vehicle's speed and communicating it to the cruise control system. If the speed sensor is faulty or dirty, the cruise control system may not work. You can test the speed sensor with a multimeter or take your vehicle to a mechanic to have it tested.
4. Check the cruise control module: If all the above steps check out, the problem may be with the cruise control module itself. The module may be faulty and may need to be replaced. You can take your vehicle to a mechanic to have the module tested and replaced if necessary.

It's always recommended to consult with a certified mechanic or technician to diagnose and fix issues related to the cruise control system in your vehicle. They will have the expertise and necessary tools to troubleshoot the problem and provide the appropriate solution.

When you turn it on does the light come on in the instrument cluster ?

Speed Control The vehicle speed control system consists of the following components:

• Speed control switches
• Speed control deactivator switch
• Speed control indicator
• Powertrain control module (PCM)
• Electronically controlled throttle body

There are three fuse's in the smart junction box , do you know where it is ? It's under the dash panel left side ! The fuse's are F2.27- 10amp , F2.32 - 10amp , F2.17 - 15 amp . They power the speed control servo ! Maybe the control switch's on the steering wheel don't work.
A little back ground on the system ! Speed Control The vehicle speed control system consists of the following components:

• Brake pedal position (BPP) switch
• Speed control actuator cable
• Speed control switches
• Speed control deactivator switch
• Speed control indicator
• Speed control actuator
• Smart junction box (SJB)
• Principles of Operation
  The speed control system is designed to maintain vehicle a set speed above 48 km/h (30 mph). After the speed control ON switch is pressed, pressing the speed control switch SET/ACCEL will activate the speed control actuator. To increase a set speed, either press and hold for continuous acceleration, or momentarily tap the speed control switch SET/ACCEL for 1.6 km/h (1 mph) acceleration increments. To decrease a set speed, press and hold the speed control switch COAST until the target speed is reached, or momentarily tap the speed control switch COAST for 1.6 km/h (1 mph) deceleration increments. When the speed control system has been disabled by tapping the brake pedal, the speed control switch RESUME can be pressed and the vehicle will return to the original set speed if the vehicle is traveling over 48 km/h (30 mph) and the speed control switch OFF has not been pressed.
  NOTE: The deactivator switch is provided as an additional safety feature. Normally, when the brake pedal is pressed, an electrical signal from the brake lamp circuit to the speed control actuator will deactivate the system. Under increased brake pedal effort, the deactivator switch will open and remove power to the speed control actuator, releasing the throttle independently of the speed control actuator.
  NOTE: The clockspring provides the electrical interface between the steering column wiring and the speed control switches in the steering wheel.
  The inputs to the speed control actuator are:
  
  • Vehicle speed signal
  • Speed control switches
  • Brake pedal position (BPP) switch
  • Deactivator switch
  The outputs of the speed control actuator are:
  
  • Speed control indicator lamp
  • Speed control actuator cable controlling the throttle position
  • Inspection and Verification
    NOTE: If any concerns are noted with the speedometer, stoplamps, or horn, address those concerns by referring to the appropriate sections before continuing speed control diagnosis.
    
    1. Verify the customer concern by operating the speed control system.
    1. NOTE: Any aftermarket modifications, including but not limited to those listed below, may cause the speed control to not operate correctly:
       • Any wiring or lamp modifications affecting the brake lamp operation
       • LED brake lamps
       • Non-factory installed trailer wiring
       • Radios (speed sensitive, auto mute)
       • Remote starters and alarms
       • Lighting and electrical accessory modifications
       Visually inspect for obvious signs of mechanical or electrical damage:
       • Visually inspect the speed control actuator and accelerator controls.
       • Visually inspect the speed control cable without removing it and ensure smooth cable operation. Inspect the speed control cable connection to the throttle body.
       • Visually inspect the accelerator cable without removing it and ensure smooth cable operation. Inspect the accelerator cable connection to the throttle body. Also check for cable interference with the carpet, bulkhead grommet, insulation and instrument panel wiring.
    1. Visually inspect for obvious signs of mechanical and electrical damage.
    2. Visual Inspection Chart Mechanical Electrical
       • Speed control actuator cable
       • Throttle linkage
       • Battery junction box (BJB) fuse(s):
         • 4 (40A)
         • 12 (60A)
       • Smart junction box (SJB) fuses:
         • 14 (15A)
         • 57 (10A)
       • Wiring harness
       • Loose or corroded connections
       • Deactivator switch
       • Brake pedal position (BPP) switch
       • Speed control switches
       • Powertrain control module (PCM)
       • Speed control actuator
       • Bulb

make sure 3rd brake light works, most likely you have a code in the EBCM (antilock brakes), some codes disable the cruise control, possible vehicle or output speed sensor or wheel speed sensor.

The first thing to check is the tail lights. The cruise control will not work if any lights are out. Changing to LED tail lights also causes the cruise to not work.

Suggest 2 basic checks:
1. check engine light on? Some severe codes may also disable cruise control (and traction control, etc.).
2. make sure your break lights aren't on. The switch on the break pedal controls the break lights, AND cancels cruise.

Fix your car right away, by clicking the link 1997 Mercury Grand Marques Workshop Service Repair Manual

If the ABS (and likely the traction control) light came on at the same time that the speedometer stopped working, you likely have a faulty wheel speed sensor at the right rear wheel. You can test this by swapping the two rear wheel speed sensors (ABS sensors). If the speedometer then works (but the ABS & Traction control lights stay on), replace the sensor that is now at the left rear (was at the right rear). If no change, you may have a fault in the ABS & Traction control - control unit.

Rear wheel speed sensor at www.bavauto.com

http://www.bavauto.com/shop.asp?HC1=0&Htarget=search.asp&HCY=2001&HCM=330i&SearchStr=rear%20abs%20sensor

There are three fuses that have to work for the cruise to operate, including the brake lights.Check fuse numbers 53,54, and 59. It can also be affected by the brake switch (and clutch switch - if equipped). The cruise also needs a connection through the brake light bulbs, which means that it will not work if the bulbs are burnt out or if you have LED tail lights. Try pulling up on the brake pedal to see if it is the brake switch. Please post your results. Thanks.

Pull up on the brake pedal. If that does not work check your brake light bulbs (LED brake lights will also keep your cruise control form working). Finally check all of the fuses. This system needs at least 3 different fuses to work properly.