Cruise Control System Ford Tempo I

DESCRIPTION & OPERATION

The cruise control system consists of operator controls, a servo (throttle actuator) assembly, a speed sensor, a clutch switch, a stoplight switch, a vacuum dump valve, an amplifier assembly, a horn relay, wiring harnesses and vacuum hoses.

The control switches are located in the steering wheel. The servo assembly is mounted in the engine compartment, and is connected to the throttle linkage with an actuator cable. The brake and clutch switches are located on the brake pedal support bracket below the dashboard. The speed control sensor is located on the transaxle. Models with electronic dashboard use a special connection to the speedometer in place of a speed sensor.

The amplifier assembly is located below the steering column on the instrument panel reinforcement.

The cruise control is only operational at speeds above 30 MPH. The system is activated when the cruise control switch is set to the "ON" position and the "SET/ACCEL" button is depressed and released. The vehicle speed will be maintained until a new speed is set, the brake or clutch pedal is depressed, or until the system is turned off. When the system has been deactivated by depressing the brake or clutch pedal, the driver can re-establish the set speed by pressing and releasing the "RESUME" button.

When the brake pedal is depressed, an electrical signal from the stoplight is sent to the amplifier, turning off the system. In addition (when the bake pedal is depressed), the vacuum dump valve mechanically releases vacuum from the servo, thus releasing the throttle independently of the amplifier control.

Actuator Cable Type (All Except Escort, Tempo & Topaz)

Disengage throttle positioner and set carburetor at hot idle speed. Remove cable retaining clip, pull on actuator cable to take up any slack and insert cable retaining clip.

Actuator Cable Type (Escort, Tempo & Topaz)

Remove speed control actuator cable retaining clip. Push actuator cable through adjuster until slight tension is felt. Insert cable retaining clip and snap into place.

Bead Type Chain (All Except Escort, Tempo & Topaz)

Adjust bead chain so chain is tight when engine is at hot idle. On vehicles with throttle positioner, adjust chain with positioner disconnected.

Bead Type Chain (Escort, Tempo & Topaz)

Remove locking pin. Pull bead chain through adjuster. Insert locking pin in best hole of adjuster for tight bead chain without opening throttle plate.

All Except Escort, Tempo & Topaz

1. Dump valve should be adjusted so that there is no vacuum leakage when brake pedal is not depressed, and there is vacuum leakage when pedal is depressed. Check with vacuum pump.
2. If adjustment is required, hold brake pedal in depressed position and push valve into valve collar as far as it will go. Place a .050-.100" (1.27-2.54 mm) shim between White valve button and pad (adapter on some models) on brake pedal.
3. Pull brake pedal fully rearward and remove shim. Valve button should now be slightly above or just touching in pad (adapter) on brake pedal.

Vacuum Dump Valve Adjustment (Except Escort, Tempo & Topaz). Scheme 1

Escort, Tempo & Topaz

The vacuum dump valve is moveable in its mounting bracket. It should be adjusted so that is closed (no vacuum leak) when brake pedal is in its normal release position (not depressed), and open when pedal is depressed. Use a hand vacuum pump to make this adjustment. (Scheme 2)

Vacuum Dump Valve Adjustment (Escort, Tempo & Topaz). Scheme 2

CLUTCH SWITCH

Prop clutch pedal in full-up position (pawl fully released from sector). Loosen switch mounting screw. Slide switch forward toward clutch pedal until switch plunger cap is approximately .030" (.76 mm) from contacting switch housing. Tighten attaching screw to complete adjustment.

TROUBLE SHOOTING

Check all electrical and vacuum connections. Press brake pedal to see if brake lights work. If not, repair brake light circuit. Check clutch switch on manual transmission vehicles. Check servo and throttle linkage for free operation. If components appear to be in good condition, proceed to following TESTING.

CONTROL SWITCHES

1. Check main feed fuse and stoplight fuse. If fuse is okay, turn ignition off and disconnect 6-pin connector at amplifier assembly. Connect ohmmeter between Light Blue/Black lead and ground.
2. Turn ignition on. Depress "ON" button and check for battery voltage. Make following tests while rotating steering wheel
3. Depress "OFF" button and check for reading from 0-1 ohm. Depress "SET/ACCEL" button and check for a reading from 646 to 714 ohms. Depress "COAST" button and check for a reading from 114 to 126 ohms.
4. Depress "RESUME" button and check for a reading from 2090 to 2310 ohms. If resistance readings are okay but meter needle fluctuates, remove steering wheel and clean contact surfaces of cruise control ground brush and turn signal brush.
5. If resistance readings are high, check switch assemblies and ground circuit in steering column.

SPEED SENSOR (EXCEPT ELECTRONIC SPEEDOMETER)

1. Disconnect speed sensor connector and connect an ohmmeter between wire connector terminals at speed sensor end. A reading of 200-300 ohms should be obtained.
2. A reading of zero ohms indicates a shorted coil, and a high reading indicates an open coil. If reading is within proper range and speedometer operates properly, sensor is probably good. Substitute a new sensor if necessary to check operation.

SPEED SENSOR (ELECTRONIC SPEEDOMETER)

1. Models with electronic speedometer do not use a separate speed sensor, but are connected directly to speedometer. To test, raise and support rear of vehicle so wheels can turn.
2. Connect an AC voltmeter to Dark Green/White lead, and ground at amplifier. With speedometer indicating 30 mph, voltmeter should read between 6 and 24 volts.

SERVO ASSEMBLY

Note. If Orange/Yellow lead is shorted to either White/Pink or Gray/Black leads, it may be necessary to replace amplifier.

1. Separate servo-to-amplifier 8-pin connector. Connect an ohmmeter between Orange/Yellow and Gray/Black wires at servo connector. Resistance should be 40-125 ohms.
2. Connect ohmmeter between Orange/Yellow and White/Pink wires. Resistance reading should be 60-190 ohms.
3. Start engine. Connect Orange/Yellow lead of servo connector to battery positive post and White/Pink lead of servo connector to ground. Momentarily touch Grey/Black lead of servo connector to ground.
4. Servo throttle actuator arm should pull in and engine speed should increase. Arm should hold this position or slowly release. If White/Pink wire is removed from ground, servo should release immediately.

AMPLIFIER

Note. DO NOT use a test light to perform amplifier test because too much current draw will damage electronic components. Use only a voltmeter of 5000 volt/ohm rating or higher.

1. Make tests at amplifier 6-pin connector. Turn ignition on and connect voltmeter between White/Purple wire and ground in connector. Battery voltage should be present. If not, check for blown fuse.
2. Connect voltmeter to Light Blue/Black wire and ground. With "ON" button in steering wheel depressed, battery voltage should be present. If not, perform control switch test.
3. Release "ON" button. Voltmeter should read 7.8 volts. If not, check system ground, wiring, fuse and circuit breaker. Install a known good amplifier and recheck, if necessary.
4. Depress "OFF" button. Voltage should drop to zero. If not, perform control switch test. Install a known good amplifier and recheck, if necessary.
5. Depress and hold "SET-ACCEL" button. Voltmeter should read 4.5 volts. Rotate steering wheel several times. If voltage varies more than 0.5 volts, perform control switch test.
6. Depress and hold "COAST" button. Voltage should be 1.5 volts. Depress and hold "RESUME" button. Voltage should be 6.5 volts. If all readings are correct, perform servo assembly test.

VACUUM DUMP VALVE

1. Disconnect dump valve vacuum hose at servo, connect hand vacuum pump to hose and apply vacuum.
2. If vacuum will not hold hose or dump valve leaks, components should be replaced or adjusted. Step on brake pedal. If vacuum is not released, adjust or replace dump valve.

Note. DO NOT use a test light to test clutch switch. Use a voltmeter with 5000 volt/ohm rating or higher.

Disconnect clutch switch connector. Connect voltmeter to switch connector terminals. With clutch pedal released, resistance should be less than 5 ohms. With clutch pedal depressed, circuit should be open. If not, replace switch.

Tempo & Topaz Cruise Control Component Location. Scheme 3

CODE-TO-TEST MENU

SABLE & TAURUS CRUISE CONTROL SERVICE CODES/TEST MENU

PINPOINT TEST A

Enter this test only when Codes 47, 48 or 49 are received in KEY ON, ENGINE OFF SELF-TEST. To prevent replacement of good components, the horn relay and/or fuses (non-IVSC areas) may be at fault. This pinpoint test is intended to diagnose only the speed control switches, brush assembly, slip ring assembly, wiring harness and the ECA.

1. Service Code 47 appears. If "OFF", "COAST", "ACCEL" and "RESUME" buttons are pressed during IVSC KEY ON, ENGINE OFF, go to Step 2). If not, perform IVSC KEY ON, ENGINE OFF SELF-TEST.
2. If switch does not function, turn key off. Wait 10 seconds. Disconnect ECA 60-pin connector. Inspect for damage. Service as necessary. Install Breakout box, leaving ECA disconnected. Measure resistance between test pin 50 and test pin 39 per table. If resistances are within range, replace ECA. If not, replace switches. If resistance values fluctuate within the ranges while steering wheel is rotated, or goes above ranges, clean brushes, slip rings and lubricate slip rings. If not, switches are okay. SABLE & TAURUS RESISTANCE RANGES Range Button Ohm Resistance 200 Ohm "OFF" 0-4 200 Ohm "COAST" 114-126 2000 Ohm "ACCEL" 646-714 5000 Ohm "RESUME" 2090-2310
3. Service Code 48 appears. If "OFF", "COAST", "ACCEL" and "RESUME" buttons are pressed during IVSC KEY ON, ENGINE OFF QUICK TEST, go to Step 4). If not, perform IVSC KEY ON, ENGINE OFF QUICK TEST.
4. If switch is stuck with key off, wait 10 seconds. Disconnect ECA 60-pin connector. Inspect for damage. Service as necessary. Install Breakout box, leaving ECA disconnected. DVOM range should be on 5000-ohm scale. If resistance reading is 0-2310 ohms, replace switches. If not, replace ECA.
5. Service Code 49 has appeared. If "OFF", "COAST", "ACCEL" and "RESUME" buttons are pressed during IVSC KEY ON, ENGINE OFF QUICK TEST, go to Step 6). If not, perform IVSC KEY ON, ENGINE OFF QUICK TEST.
6. Turn key off and wait 10 seconds. Disconnect ECA 60-pin connector. Inspect for damage. Service as necessary. Install Breakout box, leaving ECA disconnected. Disconnect speed control switch plug in steering column shroud. Set DVOM on 200-ohm scale. Measure resistance between test pin 39 and ground terminal in 14290 harness (12-pin connector) half of disconnected switch plug. If resistance reading is greater than 5 ohms, service open circuit between EEC-IV connector pin 39 and switch plug ground terminal. If not, replace ECA. (Scheme 4)

Pinpoint Test A Wiring Diagram. Scheme 4

PINPOINT TEST B

Enter this pinpoint test only when service Codes 74 or 75 are received in the KEY ON, ENGINE OFF SELF-TEST. To prevent replacement of good components, the brake light, brake switch and/or fuses (non-IVSC areas) might be at fault. This pinpoint test is intended to diagnose the BOO circuit and the ECA.

1. Service Code 74 has appeared. If brake is pressed during KEY ON, ENGINE OFF SELF-TEST, go to Step 2). If not, perform KEY ON, ENGINE OFF SELF-TEST and press brake once during test.
2. Turn key off and wait 10 seconds. Disconnect ECA 60-Pin connector. Inspect for damage. Service as necessary. Install Breakout box, leaving ECA disconnected. Set DVOM on 20-volt scale. Measure voltage between test pin 2 and test pin 40 at Breakout box while depressing and releasing brake. If voltage cycles, replace ECA and retest. If not, go to step 3).
3. Turn key off. Install Breakout box. Disconnect ECA. Set DVOM on 200-ohm scale. Disconnect BOO circuit from 14290 harness (12-pin connector). Measure resistance between test pin 2 at Breakout box and ground. If resistance reading is greater than 5 ohms, service stop light circuit. If not, service BOO circuit short to ground.
4. Turn key off and wait 10 seconds. Disconnect ECA 60-pin connector. Inspect for damage. Service as necessary. Install Breakout box, leaving ECA disconnected. Set DVOM on 20-volt scale. Measure voltage between test pin 2 and test pin 40 at Breakout box while depressing and releasing brake. If voltage cycles, replace ECA and perform QUICK TEST. If not, go to Step 5).
5. Turn key off. Install Breakout box. Disconnect ECA. Set DVOM on 20-volt scale. Disconnect BOO circuit from 14290 harness (12-pin connector). Measure voltage between test pin 2 at Breakout box and engine block ground. If voltage reading is greater than 10.5 volts, service BOO circuit short-to-power. If not, BOO circuit is okay. Service stop light circuit. (Scheme 5)

Pinpoint Test B Wiring Diagram. Scheme 5

PINPOINT TEST C

Note. Pinpoint Test C has been revised due to Ford Technical Service Bulletin 90-18B-5.

Enter pinpoint test only when service Codes 81 or 82 are received in the KEY ON, ENGINE OFF SELF-TEST. This pinpoint test is intended to diagnose only the servo vent solenoid, servo vacuum solenoid, circuits SOL+, SCVNT, SCVAC, and the ECA.

1. Turn key off. Disconnect ECA 60-pin connector. Inspect for damage. Service as necessary. Install Breakout box, leaving ECA disconnected. Set DVOM on 200-ohm scale. Measure resistance between test pin 13 and test pin 35. If resistance is 100-150 ohms, and code 82 is present go to Step 6) otherwise go to Step 4). If resistance is less than 100 ohms, replace servo and repeat QUICK TEST. If resistance is greater than 150 ohms, go to Step 2).
2. Disconnect harness connector from servo. Set DVOM on 200-ohm scale. Measure resistance between test pin 13 and SOL+ circuit at harness connector. If resistance is greater than 5 ohms, service open circuit and repeat QUICK TEST. If resistance is less than 5 ohms, go to Step 3).
3. Disconnect harness connector from servo. Set DVOM on 200-ohm scale. Measure resistance between test pin 35 and SCVNT circuit at harness connector. If resistance is greater than 5 ohms, service open circuit and repeat QUICK TEST. If resistance is less than 5 ohms, replace servo and repeat QUICK TEST.
4. Disconnect harness connector from servo. Set DVOM on 200,000-ohm scale. Measure resistance between SOL+ and test pin 60 (ground). If the resistance is greater than 10,000 ohms go to Step 5).If the resistance is less than 10,000 ohms SERVICE the shorted circuit and repeat the QUICK TEST (the short may have caused damage to the ECA).
5. Disconnect harness connector from servo. Set DVOM on 200,000-ohm scale. Measure resistance between SCVNT and test pin 60 (ground). If the resistance is greater than 10,000 ohms replace the ECA and repeat QUICK TEST. If the resistance is less than 10,000 ohms SERVICE the shorted circuit and repeat the QUICK TEST.
6. Turn key off. Disconnect ECA 60-pin connector. Inspect for damage. Service as necessary. Install Breakout box, leaving ECA disconnected. Set DVOM on 200-ohm scale. Measure resistance between test pin 13 and test pin 42. If resistance is 40-75 ohms, go to Step 9). If resistance is less than 40 ohms, replace servo and repeat QUICK TEST. If resistance is greater than 75 ohms, go to Step 7).
7. Disconnect harness connector from servo. Set DVOM on 200-ohm scale. Measure resistance between test pin 13 and SOL+ circuit at harness connector. If resistance is greater than 5 ohms, service open circuit and repeat QUICK TEST. If resistance is less than 5 ohms, go to Step 8).
8. Disconnect harness connector from servo. Set DVOM on 200-ohm scale. Measure resistance between test pin 42 and SCVAC circuit at harness connector. If resistance is greater than 5 ohms, service open circuit and repeat QUICK TEST. If resistance is less than 5 ohms, replace the servo and repeat QUICK TEST. (Scheme 6)
9. Disconnect harness connector from servo. Set DVOM on 200,000-ohm scale. Measure resistance between SOL+ and test pin 60 (ground). If the resistance is greater than 10,000 ohms go to Step 10).If the resistance is less than 10,000 ohms SERVICE the shorted circuit and repeat the QUICK TEST (the short may have caused damage to the ECA).
10. Disconnect harness connector from servo. Set DVOM on 200,000-ohm scale. Measure resistance between SCVAC and test pin 60 (ground). If the resistance is greater than 10,000 ohms replace the ECA and repeat QUICK TEST. If the resistance is less than 10,000 ohms SERVICE the shorted circuit and repeat the QUICK TEST.

Pinpoint Test C Wiring Diagram. Scheme 6

PINPOINT TEST D

Enter this test only when code 36 is received in the KEY ON, ENGINE RUNNING SELF-TEST. This pinpoint test is intended to diagnose the actuator cable adjustment, vacuum hose connections, dump valve adjustment and the ECA.

1. Service Code 36 appears. Repeat KEY ON, ENGINE RUNNING SELF-TEST. Ensure speed control "ON" button is pressed before pressing "STAR" push button. If Code 36 is still present, go to Step 2). If not, increased-vehicle-speed test passed. Service any other service codes that appear as necessary.
2. If actuator cable is attached to throttle body accelerator linkage, go to Step 3). If not, connect servo cable to throttle body accelerator linkage. Repeat QUICK TEST.
3. If servo vacuum supply hose is connected to servo and vacuum manifold, go to Step 4). If not, connect hoses and repeat QUICK TEST. If dump valve hose is connected to servo and to dump valve, go to Step 4). If not, connect hoses and repeat QUICK TEST.
4. If dump valve is adjusted properly so that valve is closed when brake pedal is not depressed, replace ECA. If not, adjust dump valve and repeat QUICK TEST.

PINPOINT TEST E

Enter this pinpoint test only when service Codes 27 and/or 28 are in the KEY ON, ENGINE RUNNING SELF-TEST. This pinpoint test is intended to diagnose speed control servo and vacuum hose connections (servo-to-manifold and servo-to-dump valve).

1. Service Code 27 appears. Repeat KEY ON, ENGINE RUNNING SELF-TEST. Ensure speed control "ON" button is pressed before pressing "STAR" push button. If Code 27 is still present, go to Step 2). If not, the servo leaks-down-test passed. Service any other service code that may appear.
2. ) If servo vacuum supply hose is not tightly connected to servo and vacuum manifold, and is not free of cuts or cracks, service vacuum hoses. Repeat QUICK TEST. If okay, replace servo and repeat QUICK TEST. If dump valve hose is not tightly connected to servo and dump valve, and is not free of cuts or cracks, service vacuum hoses. Repeat QUICK TEST. If okay, replace servo and repeat QUICK TEST.
3. Service Code 28 appears. Repeat KEY ON, ENGINE RUNNING SELF-TEST. Ensure speed control "ON" button is pressed before pressing "STAR" push button. If Code 28 is still present, replace servo and repeat QUICK TEST. If not, servo leaks-up-test passed. Service any other service codes that appear as necessary.

PINPOINT TEST F

Enter this pinpoint test only when service Code 37 is received in the KEY ON, ENGINE RUNNING SELF-TEST. This pinpoint test is intended to diagnose the actuator cable adjustment, throttle shaft and linkage, throttle position sensor and the ECA.

1. Service Code 37 appears. Repeat KEY ON, ENGINE RUNNING SELF-TEST. Ensure the speed control "ON" button is pressed before pressing the "STAR" push button. If Code 37 is still present, go to Step 2). If not, decrease-vehicle-speed test passed. Service any other service codes that appear as necessary.
2. If throttle shaft or throttle linkage is binding, service to eliminate binding and repeat QUICK TEST. If not, go to Step 3).
3. If actuator cable binds, replace actuator cable. If not, go to Step 4).
4. If throttle position sensor is binding, replace throttle position sensor and repeat QUICK TEST. If not, replace ECA and repeat QUICK TEST.

PINPOINT TEST G

Enter this pinpoint test only when directed by the KEY ON, ENGINE RUNNING SELF-TEST. This pinpoint test is intended to diagnose the speed sensor resistance, short in sensor input circuit, and open in sensor input circuit.

1. Turn key off, and wait 10 seconds. Disconnect ECA 60-pin connector. Inspect for damage. Service as necessary. Install Breakout box, leaving the ECA disconnected. Set DVOM to 2000-ohm scale. Measure resistance between test pin 3 and test pin 6. If DVOM reads less than 180 ohms, go to Step 2). If DVOM reads greater than 240 ohms, go to Step 3). If DVOM reading is 180-240 ohms, replace ECA and repeat QUICK TEST.
2. Turn key off. Disconnect harness connector from vehicle speed sensor. Set DVOM on 2000-ohm scale. Measure resistance between 2 connector pins on speed sensor. If DVOM reads less than 180 ohms, replace speed sensor and repeat QUICK TEST. If DVOM reading is 180-240 ohms, repair open in wire harness between sensor and EEC-IV pins 3 and 6. Repeat QUICK TEST. (Scheme 7)

Pinpoint Test G Wiring Diagram. Scheme 7

PINPOINT TEST Q

Enter this pinpoint test only when directed from KEY ON, ENGINE RUNNING or KEY ON, ENGINE OFF SELF-TEST. This pinpoint test is intended to diagnose only the ECA and harness circuits (signal return, STO, STI, and ground).

1. Turn key off and wait 10 seconds. Disconnect ECA 60-pin connector and inspect for damage. Service as necessary. Install Breakout box, leaving ECA disconnected. Set DVOM to 200-ohm scale. Measure resistance between SELF-TEST input at SELF-TEST single pin connector and test pin 48 at Breakout box. If less than 5 ohms, go to Step 2). If greater than 5 ohms, correct open in circuit.
2. Install Breakout box. Set DVOM to 200-ohm scale. Measure resistance between SELF-TEST output at SELF-TEST connector and test pin 17 at Breakout box. If less than 5 ohms, go to Step 3). If greater than 5 ohms, correct open in circuit.
3. Install Breakout box. Turn key off. Measure resistance between EGO ground on engine and test pin 49 at Breakout box. If less than 5 ohms, go to Step 4). If greater than 5 ohms, check and service EGO sensor ground wire or open circuit.
4. Install Breakout box. Set DVOM on 200,000-ohm scale. Measure resistance between SELF-TEST output at SELF-TEST connector and engine block ground. If resistance is greater than 10,000 ohms, replace ECA and repeat QUICK TEST. If not, service shorts to ground and repeat QUICK TEST. (Scheme 8)

Pinpoint Test Q Wiring Diagram. Scheme 8

Removal & Installation

1. Remove air cleaner. Remove retaining clip screw and disconnect actuator cable or bead chain from accelerator cable bracket. Disconnect actuator cable with adjuster from accelerator cable.
2. Remove all vacuum hoses and electrical connector from servo. Remove 2 nuts holding servo to mounting bracket. Carefully remove servo and cable assembly.
3. Remove 2 nuts holding cable cover to servo. Pull off cover and remove cable or bead chain assembly. To install, reverse removal procedure.

Remove screws securing amplifier to mounting bracket. Disconnect electrical connections to amplifier and remove amplifier. To install, reverse removal procedure.

Removal & Installation (All Except Escort, Tempo & Topaz)

1. Raise vehicle on hoist. Remove bolt retaining speed sensor mounting clip to transmission or transaxle. Remove sensor and driven gear from transmission or transaxle. Disconnect electrical connector and speedometer cable from speed sensor.
2. Disconnect speedometer cable by pulling it out of speed sensor. Do not attempt to remove spring retainer clip with speedometer cable in sensor. Remove driven gear retainer. Remove driven gear from sensor. To install, reverse removal procedures.

Removal & Installation (Escort, Tempo & Topaz)

1. The speed sensor is located on transmission (Tempo/Topaz), or in engine compartment (Escort). Raise vehicle on hoist and loosen retaining nut holding sensor in transmission. Remove sensor from transmission.
2. Disconnect electrical connector from sensor. Disconnect speedometer cable by pulling it out of speed sensor. DO NOT attempt to remove spring retainer clip with speedometer cable in sensor. To install, reverse removal procedures.

The ECA is located behind glove compartment under instrument panel. Disconnect electrical connector at ECA. Remove clip attaching ECA to dash panel. Remove ECA. To install, reverse removal procedures.

ENGAGEMENT SWITCH

Note. See STEERING COLUMN SWITCHES article in STEERING section for engagement switch REMOVAL & INSTALLATION procedure.

WIRING DIAGRAMS

For wiring diagrams, see WIRING DIAGRAMS article in WIRING DIAGRAM section.