Pinpoint Test B - Speed Control Operates But Does Not

WARNING: This page is about a different car, the 1996 Mercury Villager. However, it is still accessible from the selected car via links, so may be relevant.

RESUME, ACCELERATE OR COAST DOWN

WARNING: Disable air bag system before working around steering column or removing any air bag system component. See appropriate AIR BAG RESTRAINT SYSTEM article.

Test speed control switch. See the SPEED CONTROL SWITCH ASSEMBLY under TESTING. If speed control switch is okay, go to next step. If speed control switch is not okay, replace speed control switch.
Turn ignition off. Check operation of horn. If horn does not operate, diagnose and repair as necessary. Disconnect speed control amplifier connector. Measure voltage at specified wire terminals of speed control amplifier while pressing speed control switch buttons as specified. See SPEED CONTROL AMPLIFIER VOLTAGE SPECIFICATIONS table. Press only one button at a time. If voltages are as specified, replace speed control amplifier. If voltages are not as specified, go to next step.
Turn ignition off. Disconnect speed control amplifier connector and air bag sliding contact connector. Measure resistance of Blue/Red wire between speed control amplifier connector and air bag sliding contact connector. Measure resistance of White/Blue wire between speed control amplifier connector and air bag sliding contact connector. Measure resistance of Blue/Red wire between speed control amplifier connector and ground. Measure resistance of White/Blue wire between speed control amplifier connector and ground. Resistances should be less than 5 ohms between amplifier and sliding contact, and greater than 10 k/ohms between amplifier and ground. If resistances are as specified, replace speed control amplifier. If resistances are not as specified, go to next step.
Turn ignition off. Disconnect air bag sliding contact connector and speed control switch connector. Measure resistance of Yellow/Blue wire between air bag sliding contact connector and speed control switch connector. Measure resistance of Purple/Orange wire between air bag sliding contact connector and speed control switch connector. Measure resistance of Yellow/Blue wire between speed control switch connector and ground. Measure resistance of Purple/Orange wire between speed control switch connector and ground. Resistances should be less than 5 ohms between sliding contact and switch, and greater than 10 k/ohms between switch and ground. If resistances are as specified, replace air bag sliding contact. If resistances are not as specified, repair Yellow/Blue and/or Purple/Orange wire(s).