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Test B: TFT Sensor

  1. Check Signal Operation

    With ignition switch in OFF position, disconnect transaxle harness connector. Check transaxle wiring harness and connector for damage, corrosion or pushed out pins. Repair as necessary. Turn ignition switch to ON position. Using DVOM, measure voltage between transaxle harness connector terminals No. 2 and 6. See Figure . If voltage is 4.75-5.25 volts, go to step  4 . If voltage is not 4.75-5.25 volts, go to next step.

  2. Check Continuity Of TFT Sensor Signal Return Circuits

    Turn ignition switch to OFF position. Disconnect PCM connector. Check wiring harness and connector for damage, corrosion or pushed out pins. Repair as necessary. Install breakout box and leave PCM disconnected. Using DVOM, measure resistance between transaxle harness connector terminal No. 2 and breakout box terminal No. 37. See Figure . Measure resistance between transaxle harness connector terminal No. 6 and breakout box terminal No. 91. If both resistances are less than 5 ohms, go to next step. If either resistance is 5 ohms or more, repair open in affected circuit. Reconnect all connectors and repeat QUICK TEST  under DIAGNOSIS & TESTING.
    3. NOTE: Breakout box terminals No. 51 and 91 are ground circuits, terminals No. 71 and 97 are power circuits.

  3. Check TFT Circuit For Short To Power Or Ground
    Using DVOM, measure resistance between breakout box terminal No. 37 and terminals No. 51, 71, 91, 97 and ground. Resistance should be more than 10 k/ohms between each terminal. If resistance is not as specified, repair short in affected circuit. Reconnect all connectors and repeat QUICK TEST  under DIAGNOSIS & TESTING. If resistance is as specified, replace PCM. Repeat QUICK TEST  .
    4. NOTE: Begin this test with transaxle cold.

  4. Check TFT Sensor/Harness Resistance
    With transaxle harness connector disconnected, measure and record resistance between transaxle connector terminals No. 2 and 6. See Figure . Resistance should be within specification. See TFT SENSOR RESISTANCE  table. If resistance is within specification for specific temperature, either warm up transaxle or allow transaxle to cool to check resistance at different temperatures. If resistances remain within specification, go to next step. If resistances are not within specification, replace TFT sensor. Erase all trouble codes. See CLEARING DIAGNOSTIC TROUBLE CODES  under DIAGNOSIS & TESTING. Repeat QUICK TEST  under DIAGNOSIS & TESTING.
    TFT SENSOR RESISTANCE

    Temperature °F (°C) k/ohms
    267-302 (131-150) .54-.80
    231-266 (111-130) .81-1.50
    195-230 (91-110) 1.51-2.70
    159-194 (71-90) 2.71-5.00
    105-158 (41-70) 5.01-16.00
    69-104 (21-40) 16.01-37.00
    32-68 (0-20) 37.01-100
    -3 to 31 (-19 to -1) 100-284
    -40 to -4 (-40 to -20) 284-967

  5. Check TFT Sensor/Harness For Short To Ground

    Using DVOM, measure resistance between transaxle connector terminals No. 2, 6 and ground. See Figure . Resistance should be more than 10 k/ohms. If resistance is as specified, repeat QUICK TEST  under DIAGNOSIS & TESTING. If DTCs still exist after repeating QUICK TEST, check fluid condition. If fluid is okay, diagnose by symptom. See TROUBLE SHOOTING in FORD F4E-III (MAZDA FA4A-EL) OVERHAUL article. If resistance is not as specified, check internal transaxle wiring for short to ground. Repair as necessary. If internal transaxle wiring is okay, replace valve body.
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