Ford cruise control systems are easy to check on certain models with a cool self test!

© DenLorsTools.com Summary: This auto repair article covers checking Ford cruise control systems that have a unique self test. Certain models have a test built into the computer system which can help to pinpoint the cause of a malfunctioning speed control system. Entering the test mode is easy for anyone once you know the procedure. No scan tool is required for this pinpoint test!

Besides using the “educated guess method” – cruise control systems on most cars can be a little tricky to diagnose. Most techs know the simple basics when checking a cruise control system. The “rule of thumb” things to look for. 1. Does the horn work? If the horn doesn’t work, this could mean that the clock spring is bad. This creates an open circuit for the cruise control, horn and sometimes the airbag as well. 2. Do the brake lights work? If the stoplight switch (AKA brake light switch) doesn’t work, the cruise control may not either. 3. Does the speed odometer work, or is the ABS (Antilock Brake Light) on? If the speed odometer doesn’t work because a VSS (Vehicle Speed Sensor) is faulty, the cruise may not work either. Some Fords use the rear ABS speed sensor on the differential that could affect the ABS, speedometer and cruise. 4. Does the cruise work if the cruise button is held in the on position? If the cruise works when the cruise button is held, then most of the time it is because of a bad switch. 5. Does the data screen show cruise on and off? Some techs that have a scan tool which can access vehicle data can monitor the “on” and “off” indication on the scan tool screen when trying to turn the cruise on. This is a very limited test, but it can be helpful to know if the cruise is at least turning on. The on switch is a very common cause of failure.

Ford Recall

On some Fords from 1994 to 2002 , there was a common problem with a brake pressure switch mounted in the master cylinder housing that could leak and become shorted. It was called a cruise control deactivation switch. In rare cases it could overheat and create an under-hood fire. There was a major Ford recall back then for this issue.  What could happen is the switch would leak and sometimes the fluid would travel inside the insulation of the wire. If the fluid made it back far enough it could cause shorting and a fire. The fix was to replace the switch if it showed signs of leaks and the install a wiring harness that would allow the fluid to leak out in the event of a switch failure. The fluid would leak out of the insulation instead of traveling to cruise components that could cause further problems. This is similar to a problem that some GM cars had back years ago with a temperature sensor. The temp sensor could leak coolant into the electrical wire. The coolant sometimes would travel inside the insulation all the way back to the ECU (Electronic Control Unit). It was a very common problem for awhile taking out many computers. The fix was the same too. A new sensor was installed and a new pigtail was installed, allowing the coolant a way out if the sensor failed again, instead of allowing coolant to travel inside the electrical wire insulation to the ECU.

Ford Cruise Control Self test Procedure 

From around 2007 to present, many Fords have a self test feature that is very helpful. The test has more to it than is listed below. For simplification purposes we’ve broke it down to a few simple steps that can most of the time direct the car owner or tech in the right direction. For complete details of ALL the test information it’s best to access the repair manual information for the specific model being worked on. Click on the ALLData link to the right to gain full access to this info. for your particular vehicle.

Deactivator switch in the 2007 Ford Expedition located by the brake pedal.

First to manually enter the self test mode, the parking brake should be applied. 1. Hold the OFF button on the cruise. Without starting the engine and while keeping the off button held – quickly cycle the ignition key from RUN to OFF to RUN. 2. If done properly the cruise control indicator light will flash once to indicate that you have successfully entered the test mode. 3. Release the OFF switch at this time. Press the ON switch, then the RSM (Resume), then the CST (Coast), then the SET/ACCEL in that order. The cruise indicator light will flash once after each button has been pushed. That is if the buttons are in fact working. Code Chart – Count the flashes 0 Flashes means previous button could be faulty. 1 Flash means that button has passed. 2 Flashes means the stop light could be bad. (This is the main switch for the brake pedal that operates the brake lights.) 3 Flashes means the speed control deactivation switch could be defective. (This is in the image above, it is by the brake pedal also.) 4 Flashes means the clutch pedal (if has manual transmission) could be faulty. 5 Flashes means there’s an internal problem or failure with the cruise control actuator itself. it is located under the hood. The cruise control deactivator switch in the image above can be bypassed for test purposes. Simply unplug the switch and use a jumper wire between the terminals. run the self test again to verify the open circuit in the switch. It is not recommended to test drive or to leave the jumper wire in place because the cruise control will not shut off when the brakes are applied! Also it should be noted that after installing a replacement deactivator switch it will be necessary to adjust it or the system will see the brakes as “applied.” After installing the new switch, simply pull up on the brake pedal and the switch will be adjusted properly. 

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