2001 Mercury Villager BaseFACTORY OEM SERVICE PROCEDURE

Test A: EATC System

  1. Perform self-diagnostic test and record DTCs. See ENTERING SELF-DIAGNOSTICS  . If no DTCs are retrieved, go to next step. If DTCs 30, 31, 40, 41, 42 or 43 are present, go to step  10 . If DTCs 50 or 52 are present, go to step  11 .
  2. Exit self-diagnostic test by pressing defrost button. Observe function symbols on display. If display is complete with no missing elements, go to next step. If any elements are missing, go to step  18 .
  3. Start engine. Press AUTO button. If AUTO and selected temperature appear in display window, go to next step. If AUTO and/or selected temperature do not appear in window, replace EATC module. Retest system.
  4. Rotate manual blower speed switch to full HI and LO positions. If blower speeds change, go to next step. If speeds do not change, go to TEST G  .
  5. Press each of the air distribution override buttons and check for correct air distribution. If air distribution is from correct outlets, go to next step. If air distribution is incorrect, go to TEST B  .
  6. Ensure temperature is more than 50°F (28°C). Press air distribution override button to activate A/C mode. If compressor clutch engages, go to next step. If compressor clutch does not engage, go to TEST D  .
  7. Press air distribution override button to activate vent mode. If compressor clutch goes off, go to next step. If compressor clutch does not go off, go to TEST E  .
  8. Press rear window defogger button. Feel rear window defogger grid. If grid is warm, go to next step. If grid is not warm, problem is in rear window defogger system. Repair as necessary.
  9. Warm engine to normal operating temperature. Adjust temperature on EATC module to 60°F (33°C). Readjust temperature setting to 90°F (50°C). If EATC system adjusts temperature to indicated setting, system is operating properly. If temperature is not adjusted correctly, go to next step.
  10. Turn ignition off. Disconnect EATC module harness connector C2028a, located behind center of instrument panel. Measure resistance between ground and terminal No. 1 (Green/White wire) of EATC harness connector. Measure resistance between ground and terminal No. 4 (Violet wire) of EATC harness connector. Measure resistance between ground and terminal No. 5 (Red/White wire) of EATC harness connector. See Fig 1 . At 50-68°F (28-38°C), resistance should be 37,000-58,000 ohms. At 68-86°F (38-48°C), resistance should be 24,000-37,000 ohms. At 86-104°F (48-58°C), resistance should be 16,000-24,000 ohms. If resistances are as specified, go to next step. If resistance is not correct at terminal No. 1, go to step  12 . If resistance is not correct at terminal No. 4, go to step  12 . If resistance is not correct at terminal No. 5, go to step  16 .
  11. Measure resistance between ground and terminal No. 2 (Green/Black wire) of EATC module harness connector C2028a. If resistance is more than 0 ohms, replace EATC module. Retest system. If resistance is 0 ohms, replace sunload sensor. Retest system.
  12. Disconnect in-vehicle temperature sensor harness connector, located behind center of instrument panel. Measure resistance in Green/White wire between terminal No. 1 of EATC module connector and terminal No. 2 of in-vehicle temperature sensor connector. Measure resistance between ground and terminal No. 1 (Green/White wire) of EATC module harness connector. If resistance is 5 ohms or less between module and sensor, and more than 10 k/ohms between module and ground, go to next step. If resistance is not as specified, repair open or short to ground in Green/White wire. Retest system.
  13. Measure resistance between ground and terminal No. 1 (Black wire) of in-vehicle temperature sensor harness connector. If resistance is 5 ohms or less, replace in-vehicle temperature sensor. Retest system. If resistance is more than 5 ohms, repair open in Black wire between in-vehicle temperature sensor and terminal No. 3 of EATC module harness connector C2028a. Retest system.
  14. Disconnect coolant temperature sensor harness connector, located in engine compartment. Measure resistance in Violet wire between terminal No. 4 of EATC module connector and terminal No. 2 of coolant temperature sensor No. 1 harness connector. Measure resistance between ground and terminal No. 4 (Violet wire) of EATC module harness connector C2028a. If resistance is 5 ohms or less between module and sensor, and more than 10 k/ohms between module and ground, go to next step. If resistance is not as specified, repair open or short to ground in Violet wire. Retest system.
  15. Measure resistance between ground and terminal No. 1 (Black wire) of engine coolant temperature sensor No. 1 harness connector. If resistance is 5 ohms or less, replace sensor. Retest system. If resistance is more than 5 ohms, repair open in Black wire between terminal No 1 of engine coolant temperature sensor No. 1 and terminal No. 3 of EATC module harness connector C2028a. Retest system.
  16. Disconnect ambient air temperature sensor harness connector, located at front of radiator. Measure resistance in Red/White wire between terminal No. 5 of EATC module harness connector C2028a and terminal No. 1 of ambient air temperature sensor harness connector. Measure resistance between ground and terminal No. 5 (Red/White wire) of EATC module harness connector C2028a. If resistance is 5 ohms or less between module and sensor, and more than 10 k/ohms between module and ground, go to next step. If resistance is not as specified, repair open or short to ground in Red/White wire. Retest system.
  17. Measure resistance between ground and terminal No. 2 (Black wire) of ambient air temperature sensor harness connector. If resistance is 5 ohms or less, replace sensor. Retest system. If resistance is more than 5 ohms, repair open in Black wire between ambient air temperature sensor and terminal No. 3 of EATC module harness connector C2028a. Retest system.
  18. Turn ignition off. Disconnect EATC module harness connector C2028b. Turn ignition on. Measure voltage between ground and terminal No. 4 (Gray wire) of EATC module harness connector. See Fig 1 . Measure resistance between ground and terminal No. 16 (Violet wire) of EATC module harness connector C2028b. If battery voltage exists, go to next step. If battery voltage does not exist, repair circuit in question. Retest system.
  19. Turn ignition off. Measure resistance between ground and terminal No. 18 (Black wire) of EATC module harness connector C2028b. If resistance is 5 ohms or less, replace EATC module. Retest system. If resistance is more than 5 ohms, repair open in Black wire between EATC module and ground (located at right side of dashboard). Retest system.
Fig 1: Identifying EATC Module Connector Terminal Locations
G99B03725
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  • • You smell fuel, burning insulation, or see smoke.
  • • Brakes feel soft, pull hard to one side, or make grinding noises.
  • • The engine overheats, stalls repeatedly, or misfires under load.
  • • You are missing required tools, torque specs, or safe lifting equipment.
  • • You are not confident in the next step or safety outcome.

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