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Test B: Transmission Fluid Temperature Sensor

NOTE: Ensure transaxle harness connector is fully seated and in good condition before proceeding.

  1. Electronic Diagnostic Set Up

    Turn ignition switch to LOCK position. Move gearshift lever to "P" position. Connect NGS tester to DLC. Turn ignition switch to RUN position. Using NGS tester, select following commands:
    • Select DIAGNOSTIC DATA LINK
    • Select PCM
    • Select PID/DATA MONITOR AND RECORD
    Monitor TFT sensor and TFTV PIDs. If vehicle enters PID/DATA MONITOR AND RECORD, remain in PID DATA CONTROL and got to next step. If vehicle does not enter PID/DATA MONITOR AND RECORD, see appropriate SELF-DIAGNOSTICS article in ENGINE PERFORMANCE for diagnosis of PCM.

  2. Warm-Up/Cool-Down Cycle Verification

    Monitor TFT sensor PIDs. If transaxle is cold, drive vehicle to warm it up. If transaxle is warm, allow transaxle to cool down. If TFT sensor PIDs increase as transaxle is warmed or decrease as transaxle is cooled, clear all DTCs and road test vehicle to verify concern. If concern is still present, perform overheating diagnosis. See SYMPTOM DIAGNOSIS under TROUBLE SHOOTING in FORD 4F27E OVERHAUL article. If TFT or TFTV PIDs drop in and out of range, inspect for intermittent fault in transaxle internal/external wiring harness, TFT sensor and connector. If TFT PIDs do not increase as transaxle is warmed, do not decrease as transaxle is cooled or do not drop in and out of range, go to next step.

  3. Check PCM & Vehicle Harness For Power

    Disconnect transaxle 9-pin harness connector. Visually inspect all wires and connector terminals for damage. Using a voltmeter, measure voltage between ground and transaxle 9-pin harness connector (harness side) terminals No. 5 (White/Green wire) and 4 (Brown/Green wire). See Figure . If any voltage is present, go to next step. If no voltage is present, go to step  5 .

  4. Check Vehicle Harness For Short To Power

    Turn ignition switch to LOCK position. Disconnect PCM 104-pin harness connector. Turn ignition switch to RUN position. Using a voltmeter, measure voltage between ground and transaxle 9-pin harness connector (harness side) terminals No. 5 (White/Green wire) and 4 (Brown/Green wire). If any voltage is present, repair short to power in appropriate wire(s) and retest system operation. If no voltage is present, replace PCM and retest system operation.

  5. Check PCM & Vehicle Harness For Ground

    Turn ignition off. Using an ohmmeter, measure resistance between ground and transaxle 9-pin harness connector (harness side) terminals No. 5 (White/Green wire) and 4 (Brown/Green wire). If resistances are greater than 10 k/ohms, go to step  7 . If any resistance is less than 10 k/ohms, go to next step.

  6. Check Vehicle Harness For Short To Ground

    Disconnect PCM 104-pin harness connector. Using an ohmmeter, measure resistance between ground and transaxle 9-pin harness connector (harness side) terminals No. 5 (White/Green wire) and 4 (Brown/Green wire). If resistances are greater than 10 k/ohms, replace PCM and retest system operation. If any resistance is less than 10 k/ohms, repair short to ground in appropriate wire and retest system operation.

  7. Check Vehicle Harness For Open

    Install EEC-V breakout box. Using an ohmmeter, measure resistance in White/Green wire between transaxle 9-pin harness connector terminal No. 5 and PCM 104-pin harness connector (or breakout box) terminal No. 37. Measure resistance in Brown/Green wire or Brown wire between transaxle 9-pin harness connector terminal No. 4 and PCM 104-pin harness connector (or breakout box) terminal No. 91. See Figure . If resistances are less than 5 ohms, go to step  10 . If any resistance is greater than 5 ohms, repair open in appropriate wire and retest system operation.

  8. Check Internal Transaxle Harness For Short To Ground

    Using an ohmmeter, measure resistance between ground and transaxle 9-pin harness connector (component side) terminals No. 4 and 5. If resistances are greater than 10 k/ohms, go to next step. If any resistance is 10 k/ohms or less, replace transaxle internal wiring harness and retest system operation.

  9. Check Internal Transaxle Harness For Open

    Using an ohmmeter, measure resistance between transaxle 9-pin harness connector terminal No. 5 and TFT sensor internal wire connector terminal No. 5. See Figure . Measure resistance between transaxle 9-pin harness connector terminal No. 4 and TFT sensor internal wire connector terminal No. 4. If resistances are less than 5 ohms, go to next step. If any resistance is greater than 5 ohms, replace transaxle internal wiring harness and retest system operation.

  10. Check Resistance Of TFT Sensor

    Using an ohmmeter, measure resistance between transaxle 9-pin harness connector terminal No. 5 and TFT sensor internal wire connector terminal No. 5. Measure resistance between transaxle 9-pin harness connector terminal No. 4 and TFT sensor internal wire connector terminal No. 4. Record resistance value at specified temperature. See TFT SENSOR RESISTANCE  table. If resistances are as specified, perform overheating diagnosis. See SYMPTOM DIAGNOSIS under TROUBLE SHOOTING in FORD 4F27E OVERHAUL article. If any resistance is not as specified, replace TFT sensor and retest system operation.
    TFT SENSOR RESISTANCE

    Temperature °F (°C) (K/Ohms)
    -4 (-20) 236-317
    32 (0) 82.2-107
    68 (20) 33.5-41.2
    104 (40) 14.6-17.6
    140 (60) 7.08-8.01
    176 (80) 3.61-4.06
    212 (100) 1.96-2.20
    248 (120) 1.13-1.25
    266 (130) 0.87-0.96
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