Speed Control does not work

Asked by Mar 10, 2017 at 12:54 PM about the 2007 Mercury Grand Marquis GS

Question type: Maintenance & Repair

I replaced the switch on the brake. The horn does work. I don't see a specific
fuse just for speed control, but all other electronics work. Any thoughts?

3 Answers

85,305

If your check engine light is on, the cruse control will not work until you fix the problem that causes the check engine light to come on.

Check engine light is not on

10

Unhook neg battery cable. 2 screws on the back of the steering wheel. Unhook airbag. Reconnect battery. Test resistance. On pin 4(dark green wire)check voltage should be 0 then when brakes are applied should read 12V. This is the signal from the brake light switch. On pin 9(orange wire) you should have 12V then goes to 0 when braakes are applied. This is the cruise deactivation switch. On pin 7(white/violet) you should have 12V this is the main power feed from fuse 15 Pin 10(pink/orange) this is the ground. Pin 5(light blue/black) is the refernce voltage to the steering wheel switches and pin 6(dark green/orange) is the signal return from the switches. You can check the switches in the following manner: With the speed control actuator switch depressed to the ON position, measure the voltage between speed control actuator C122 pin 5, circuit 151 (LB/BK), harness side and speed control actuator C122 pin 10, circuit 676 (PK/OG), harness side does it read 10V or more? With the SET/ACCEL switch depressed, measure the resistance between speed control actuator C122 pin 5, circuit 151 (LB/BK), harness side and speed control actuator C122 pin 6, circuit 848 (DG/OG), harness side. Is the resistance between 646 and 714 ohms? With the COAST switch depressed, measure the resistance between speed control actuator C122 pin 5, circuit 151 (LB/BK) harness side and speed control actuator C122 pin 6, circuit 848 (DG/OG), harness side. Is the resistance between 114 and 126 ohms? With the SET/ACCEL switch depressed and while rotating the steering wheel from stop to stop, measure the resistance between speed control actuator C122 pin 5, circuit 151 (LB/BK), harness side and speed control actuator C122 pin 6, circuit 848 (DG/OG), harness side. Is the resistance between 646 and 714 ohms at all times? With the RESUME switch depressed and while rotating the steering wheel from stop to stop, measure the resistance between speed control actuator C122 pin 5, circuit 151 (LB/BK), harness side and speed control actuator C122 pin 6, circuit 848 (DG/OG), harness side. Is the resistance between 2,090 and 2,310 ohms? With the OFF switch depressed and while rotating the steering wheel from stop to stop, measure the resistance between the speed control actuator C122 pin 5, circuit 151 (LB/BK), harness side and speed control actuator C122 pin 6, circuit 848 (DG/OG), harness side. Is the resistance less than 5 ohms with the switch pressed and greater than 10,000 ohms with the switch released? Also check the cable on both ends make sure it is not broken loose at either end. If all of these are good then the cruise servo is most likely the culprit.

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