Cruise Control System - Electronic Ford Crown Victoria I

Scheme 1

SERVO CONNECTOR TERMINALS CHART

Check Power To Servo

Unplug harness connector from servo. Turn ignition on. Using DVOM, measure voltage between pins No. 7 and 10 of servo connector. (Scheme 1) If battery voltage exists, go to CHECK POWER TO DEACTIVATOR SWITCH step. If battery voltage does not exist, check for battery voltage between pin No. 7 and chassis ground. If battery voltage exists, go to next step. If battery voltage does not exist, check or circuit for open. Repair or replace as necessary.

Check Module Ground

Measure resistance between pin No. 10 and chassis ground. If resistance is less than one ohm, repeat previous step. If resistance is greater than one ohm, repair ground circuit.

Check Deactivator Switch Circuit

With brake released, measure voltage between pins No. 9 and 10 of servo connector. If battery voltage exists, go to CHECK BRAKE SWITCH step. If battery voltage does not exist, unplug connector from deactivator switch, located at the brake proportioning valve on vehicles with ABS, or junction block below brake booster on vehicles without ABS. Measure resistance between both pins of switch. (Scheme 2) If resistance is less than 5 ohms, go to next step. If resistance is greater than 5 ohms, replace deactivator switch.

Check Power To Deactivator Switch

Measure voltage between Light Green/Red wire of deactivator switch and ground. If battery voltage does not exist, check for blown fuse or open circuit. If battery voltage exists, measure resistance of Orange wire between deactivator switch and servo. If resistance is greater than one ohm, repair open circuit in wiring. If resistance is less than one ohm, repeat previous step.

Check Brake Switch

1. Measure voltage between pins No. 4 and 10 of servo connector. If battery voltage exists, replace brake switch. If battery voltage does not exist, go to next step.
2. Measure voltage between pins No. 4 and 10 at servo while depressing brake pedal. If battery voltage is present, go to next step. If battery voltage is not present, replace BOO switch or repair brakelight circuit.

Check ON Switch Operation

Measure voltage between pins No. 5 and 10 of servo connector. If battery voltage exists, replace ON switch. If battery voltage does not exist, press ON switch and measure voltage between pins No. 5 and 10 of servo connector. If battery voltage is present, go to next step. If battery voltage does not exist, check fuses, horn relay and related wiring.

Check Clockspring

Disconnect clockspring connector at base of steering column. Disable air bag system. Remove drivers air bag module. See AIR BAG RESTRAINT SYSTEM article in the ACCESSORIES/SAFETY EQUIPMENT section. Disconnect clockspring connectors in steering wheel. Measure resistance across matching color wires. If resistance is greater than 0.5 on any circuit, replace clockspring. If resistance is less than 0.5 ohm, go to next step.

Check Circuits From Clockspring To Servo

Disconnect servo electrical connector. Measure resistance between servo terminals 5 and same color wire in clockspring connector (harness side) at base of steering column. (Scheme 1) Repeat procedure for servo connector terminal 6. If resistance is greater than 3 ohms repair suspect wire(s). If resistance is less than 3 ohms, check circuits for short to ground and repair as necessary. If okay, go to next step.

Check Control Switches

To check switches, measure resistance between pins No. 5 and 6 of servo connector while pressing each control button. If any resistance is not as specified, replace faulty switch. See CONTROL SWITCH TESTING table. If all resistances are as specified, go to next step.

CONTROL SWITCH RESISTANCES

Check Vehicle Speed Sensor (VSS) Circuit

To check VSS circuit, measure resistance between pins No. 3 and 10 of servo connector. If resistance is 200-300 ohms, go to next step. If resistance is not 200-300 ohms, unplug VSS connector, located at left rear of transmission. Measure resistance between VSS terminals. If resistance is not 200-300 ohms, replace VSS. If resistance is 200-300 ohms, check for open or short in circuit.

Check For Broken Or Binding Servo Cable

Remove servo cable from servo. Check for broken or binding cable by pulling on cable ball slug. Replace cable as necessary. If cable is okay, replace servo.

Check Servo Cable & Throttle Linkage For Binding

Verify condition. Ensure engine is properly tuned. If condition occurs when cruise control is off, repair engine as required. If condition only occurs when cruise control is activated, check servo cable, throttle linkage, or throttle plate for binding or sticking. Repair as necessary.

Checking Vehicle Speed Sensor (VSS) & Servo

Unplug VSS connector, located at left rear of transmission. Measure resistance between VSS terminals. If resistance is not 200-300 ohms, replace VSS or repair circuit. If resistance is 200-300 ohms, substitute a known good servo. Test drive vehicle and check for proper operation. If system is okay, replace servo. If system is not okay, check MAP and EVP sensors.

PINPOINT TEST C - SYSTEM DOES NOT DISENGAGE WHEN BRAKES ARE APPLIED

Unplug servo connector. With brakes applied, measure voltage between pins No. 4 and 10 of servo harness connector. (Scheme 1) If battery voltage exists, replace servo. If battery voltage does not exist, replace brake switch or fuse, or repair for open circuit. To check for binding of servo cable and linkage to throttle body, remove servo cable from servo. Check for breaks or binding by pulling on cable ball slug. Ensure throttle moves freely. Replace cable as necessary. If cable is okay, replace servo assembly.

PINPOINT TEST D - OFF SWITCH INOPERATIVE

Unplug servo connector. With OFF button pressed, measure resistance between pins No. 5 and 6 of servo harness connector while rotating steering wheel. If resistance is less than 4 ohms, replace servo. If resistance is greater than 4 ohms, replace OFF switch.

DESCRIPTION & OPERATION

Major components of the cruise control system are operator controls, servo, vehicle speed sensor, horn relay, stoplight switch, deactivator switch, and related wiring. This system does not require engine vacuum. An electronic servo actuates the throttle. All electronic control components are contained within the servo assembly.

The system is operational only at speeds greater than 30 MPH. The system is activated when ON/OFF switch is switched on and SET/ACCEL button is pressed and released. Vehicle will maintain set speed until new speed is set, brake pedal is pressed, or ON/OFF switch is switched off. If system has been deactivated by pressing brake pedal, set speed can be regained by pressing and releasing RESUME button. When brake pedal is pressed, a signal from switch is sent to the amplifier to deactivate the system. Under brake pressure, deactivator switch opens to disconnect signal to servo.

SERVO LINKAGE

Remove cable retaining clip from cable adjuster. Ensure throttle is fully closed. Pull servo cable to take up any slack. Loosen at least one notch so there is approximately .12" (3 mm) of slack in cable. Insert cable retaining clip and snap into place.

TROUBLE SHOOTING

Inspect all electrical connections. Check fuse. Inspect servo and throttle linkage for free operation. Free up as necessary. If electrical connections appear okay, go to TESTING & DIAGNOSIS.

REMOVAL & INSTALLATION

Remove retaining clip from actuator cable adjuster fitting. Push servo tube out of adjuster fitting attached to throttle cable. Unplug servo harness connector. Remove retaining nuts and servo. Remove cable cap from servo. Remove cable ball slug from pulley. To install, reverse removal procedure.

Disconnect negative battery cable. Remove air bag module retaining nuts. Unplug air bag module electrical connector from clockspring contact connector. Remove air bag. Pry off cruise control switch bezel. Remove retaining screws and switch assembly. To install, reverse removal procedure.

Cruise Control System Wiring Diagram. Scheme 2

See also:
• AIR BAG RESTRAINT SYSTEM
• COMPUTER RELEARN PROCEDURES