I would start by doing the cruise control self check
Speed Control Self-Test Diagnostics
WARNING: This test is a key on engine off (KOEO) test only that is conducted in PARK only with the emergency brake fully engaged.
NOTE: A review of the following test steps is required before carrying out the Self-Test Diagnostic procedure. After entering the diagnostic mode, the module will time out if the mandatory switch sequence is not completed within 5 seconds. If a module time out occurs, the procedure must be reinitiated.
1. Enter the Self-Test Diagnostics by pressing the speed control OFF switch while turning the ignition key ON, making sure the engine does not start and is not running. Five additional flashes at this point indicate a defective speed control actuator. Release the OFF switch.
- Press and release the remaining switches in this sequence: ON, RESUME, COAST and SET/ACCEL (for Expedition), ON RESUME, COAST and CANCEL (for Navigator).
The speed control indicator lamp will flash after each switch is pressed and released. Press and release each switch in the sequence immediately after the indicator light goes out for the previous switch.
- NOTE: There will be a slight delay when the last button is pressed and released and the lamp flashes.
A lamp flash with the last button (SET/ACCEL) or CANCEL (for Navigator) 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 switches are defective.
If the lamp does not flash with the last button, and additional flashes occur, follow the chart below for trouble codes:
NOTE: If unable to enter self-test,
Go To Pinpoint Test D