Cruise control diagnostic procedure


Old 03-11-14, 06:17 AM
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Cruise control diagnostic procedure

While perusing the internet I came across this information that I just HAVE to share. First a short story:

Several years back my cruise control started working intermittently for a day or two. It seemed like I needed to push the "resume" button really hard to get it to actually resume. Then one day it finally quit and never worked again. I always assumed it was the button but had no way of knowing for sure. Years go by. Then I find this, and verified that it was indeed the right side switch that had gone bad... because the left side button starts the diagnostic, but the right side switch doesn't even respond. So here is the tip:

Ford vehicles have an on-board diagnostic system that will test the cruise control components. (Why in the world wouldn't this info be in the Chilton's repair manual???)

Self-Test Diagnostics

This test is a key on engine off (KOEO) test only that is conducted in park only with emergency brake fully engaged.

1. Enter self-test diagnostics by depressing the speed control OFF switch while turning the ignition key ON, making sure the engine does not start and is not running. The speed control indicator on the instrument panel will flash once to indicate that speed control module entered the diagnostic mode. Five additional flashes at this point indicate a defective speed control servo. Release the OFF switch.

2. Press the remaining switches in this sequence: ON, RESUME, COAST and SET/ACCEL.

If the ON switch is not depressed within five seconds after entering the diagnostics mode, the module times out and the procedure must be started over.

The speed control indicator lamp will flash as each switch is depressed. Press each switch in the sequence immediately after the indicator light goes out for the previous switch.

There will be a slight delay when the last button is pressed and the lamp flashes.

3. A lamp flash with the last button (SET/ACCEL) indicates that the static test passed. If the lamp does not flash with the last button and there are no additional flashes of the lamp, the switch is defective.

If the lamp does not flash with the last button, and additional flashes occur, follow the chart below for trouble codes:

2 flashes - BPP defective, circuit is defective, brake applied, CPP switch or jumper (if equipped).

3 flashes - deactivator switch is open or circuit defective.

4 flashes - vehicle speed signal is out of range or circuit is defective

4. Immediately (.25 second delay) after the static test, the speed control servo does a dynamic test by automatically actuating the throttle lever from 8 mm (0.315 in) to 12 mm (0.472 in) of travel from the idle position. During the dynamic throttle pull, observe throttle movement to witness any binding or sticking of the speed control cable and correct connection of speed control cable to throttle lever. Make sure the throttle returns to the idle position.

5. Return the ignition switch to the OFF position and proceed to the Symptom Chart.
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Old 03-12-14, 06:55 AM
Join Date: Jun 2010
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It would help if we knew what make/model/year you are talking about.
Old 03-12-14, 06:39 PM
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Ford vehicles have an on-board diagnostic system
Sorry I don't know to which years the above applies. I would assume they started using this in the late 80's or early 90's.

Where's the snarky icon? LOL

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