Test M: Set Speed Fluctuates
- Check That Condition Occurs Only While Using Speed Control - Ensure engine is properly tuned. Ensure problem does not occur while driving vehicle without speed control activated. If problem occurs without speed control activated, repair engine as necessary. If problem occurs only with speed control activated, go to next step.
- Check For Binding In Speed Control Cable & Throttle Body Linkage - Check for binding or sticking speed control servo/actuator cable, throttle linkage and/or throttle plate. Ensure throttle cable bracket and speed control servo/actuator bracket are not loose. Repair as necessary and perform SELF-DIAGNOSTIC TEST under SELF-DIAGNOSTIC SYSTEM. If all components are okay, go to next step.
- Check Speedometer Operation - Test drive vehicle and observe speedometer operation. If speedometer operates properly, go to next step. If speedometer does not operate properly, see INSTRUMENT PANEL article to continue diagnosis.
- Check Gray/Black Wire For Open - On Taurus SHO, disconnect ABS control module connector C1057 (located behind left headlight). Using an ohmmeter, check resistance in Gray/Black wire between speed control servo/actuator connector C102 terminal No. 3 and ABS control module connector C1057. On all other models, disconnect vehicle speed sensor connector C1043 (located near upper center of transaxle). Using an ohmmeter, check resistance in Gray/Black wire between speed control servo/actuator connector C102 terminal No. 3 and vehicle speed sensor connector C1043. On all models, if resistance is less than 5 ohms, replace speed control servo/actuator and perform self-test diagnostics. If resistance is 5 ohms or more, repair open in Gray/Black wire and perform SELF-DIAGNOSTIC TEST under SELF-DIAGNOSTIC SYSTEM.