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Home >> Ford >> 2002 >> ZX2 Automatic >> Repair and Diagnosis >> Transmission >> Automatic Trans >> Shift Interlock System >> System Tests >> Pinpoint Test A (Escort & ZX2) >> Diagnostic Procedure
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Diagnostic Procedure

NOTE: See appropriate wiring diagram to diagnose electrical circuits and identify fuses and circuit numbers. See CONNECTOR IDENTIFICATION  and WIRING DIAGRAMS  .
  1. Turn ignition switch to OFF position. On Escort, check METER fuse (10-amp), ROOM fuse (10-amp) and STOP fuse (15-amp). On ZX2 Coupe models, check HORN fuse (15-amp), METER fuse (10-amp) and STOP fuse (20-amp). Are the fuses okay? If so, go to next step. If not, replace the fuse in question and test the system for normal operation. If the fuse fails again, check for short to ground in appropriate circuit. Repair as necessary and test the system for normal operation.
  2. Ensure ignition switch is in OFF position. Disconnect shift interlock actuator harness connector. Turn ignition switch to ON position. Measure the voltage between ground and shift interlock actuator harness connector terminals No. 3 and 4. See Fig 1. Are the voltages greater than 10 volts? If so, go to next step. If not, repair open in appropriate circuit and test the system for normal operation.
  3. Turn ignition switch to OFF position. Depress and hold the brake pedal. Measure the voltage between shift interlock actuator harness connector terminal No. 1 (Green wire) and ground. See Fig 2. Is the voltage greater than 10 volts? If so, release the brake pedal and go to step  6. If not, go to next step.
  4. Disconnect Brake Pedal Position (BPP) switch. Measure voltage in Green/White wire at BPP switch harness connector. Is the voltage greater than 10 volts? If so, go to next step. If not, repair open in Green/White wire and test the system for normal operation.
  5. Measure resistance between terminals No. 1 and 2 of BPP switch while the brake pedal is depressed. Is the resistance less than 5 ohms? If so, repair open in Green wire between shift interlock actuator relay and BPP switch and test the system for normal operation. If not, replace BPP switch. See BRAKE PEDAL POSITION SWITCH  under REMOVAL & INSTALLATION. After repairs, test the system for normal operation.
  6. Disconnect park range switch harness connector. Measure the resistance between park range switch and ground. See Fig 3. Is the resistance less than 5 ohms? If so, go to next step. If not, repair open in Black wire and test the system for normal operation.
  7. Measure the resistance between the park range switch terminals (component side), while pressing and releasing the park release button, then measure the resistance between the park range switch terminals with the shifter in the Reverse, Drive and Low positions. Is the resistance less than 5 ohms with the park release button out, and greater than 10 k/ohms with the park release button in or the shifter in the Reverse, Drive and Low positions? If so, replace the shift interlock actuator. See SHIFT INTERLOCK ACTUATOR  under REMOVAL & INSTALLATION. After repairs, test the system for normal operation. If not, replace the gearshift selector lever and test the system for normal operation. See GEARSHIFT LEVER UNIT  under REMOVAL & INSTALLATION.
Fig 1: Checking For Voltage At Shift Interlock Actuator Harness Connector Terminals No. 3 & 4
G00104191Courtesy of FORD MOTOR CO.
Fig 2: Checking For Voltage At Shift Interlock Actuator Harness Connector Terminal No. 1
G00104192Courtesy of FORD MOTOR CO.
Fig 3: Measuring Resistance Between Park Range Switch & Ground
G00104213Courtesy of FORD MOTOR CO.
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