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Test B: Transmission Fluid Temperature (TFT) Sensor

  1. AX4N Electronic Diagnostics  Check transaxle harness connector. Inspect connector for damaged pins, corrosion and loose wires. Ensure transaxle connector is fully seated. Repair as necessary. Go to next step.
  2. Check Electrical Signal Operation  Ensure ignition is off. Disconnect transaxle connector. Using DVOM, connect positive lead to transaxle harness connector terminal No. 5 and negative lead to terminal No. 9. See Figure . Turn ignition on. If voltage is 4.5-5.25 volts, go to step 6). If voltage is not within specification, go to next step.
  3. Check Continuity Of TFT Signal Return (SIG RTN) Circuits  Turn ignition off. Disconnect PCM 104-pin connector, and inspect it for damaged pins, corrosion and loose wires. Repair as necessary. Install breakout box, leaving PCM disconnected. Measure and record resistance between breakout box test pin No. 37 and transaxle harness connector terminal No. 5. See Figure . Measure and record resistance between test pin No. 91 and transaxle harness connector terminal No. 9. If each resistance is less than 5 ohms, go to next step. If any resistance is more than 5 ohms, repair open circuit. Connect all components. Erase trouble codes. See CLEARING CODES  . Repeat QUICK TEST  .
  4. Check TFT Circuit For Short To VPWR & Ground  Ensure ignition is off. Disconnect PCM 104-pin connector, and inspect it for damaged pins, corrosion and loose wires. Repair as necessary. Install breakout box, leaving PCM disconnected. Measure and record resistance between breakout box test pin No. 37 and test pins No. 71 and 97. Measure and record resistance between test pins No. 24, 51, 76, 77, 91, 103 and test pin 37, and ground. If any resistance is less than 10 k/ohms, repair short circuit. Disconnect breakout box and repeat QUICK TEST  . If resistance is 10 k/ohms or more, go to next step.
  5. Check Resistance Of TFT Sensor/Harness  Install transmission tester. Set tester Bench/Drive switch to BENCH position. Set Solenoid Selector switch to OHMS CHECK. Connect ohmmeter leads to appropriate TFT jacks. Measure and record resistance. Resistance should be within specification. See appropriate TFT TEMPERATURE/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 measured remain within specification, go to next step. If resistances measured are not within specification, go to step 7).
    TFT TEMPERATURE/RESISTANCE

    Temperature °F (°C) Resistance (k/Ohms)
    32-68 (0-20) 37-100
    59-104 (21-40) 16-37
    105-158 (41-70) 5-16
    159-194 (71-90) 2.7-5
    195-230 (91-110) 1.5-2.7
    231-266 (111-130) .8-1.5
    267-302 (131-150) .54-.8
  6. Check TFT Sensor/Harness For Short To Ground  Check continuity between BAT (-) tester jack and TFT jacks. If continuity exists, go to next step. If continuity does not exist, replace PCM. Erase all DTCs. See CLEARING CODES  . Road test vehicle. Repeat QUICK TEST  . If DTC is still present, go to next step.
  7. AX4N Internal Electronic Diagnostics  Drain transaxle fluid. Remove transaxle side cover. Inspect internal harness connector at TFT sensor. Ensure all connectors are fully connected and not damaged. If all connectors are okay, go to next step. Repair as needed. Install all components in reverse order of disassembly. Fill transaxle with fluid. Erase all DTCs. See CLEARING CODES  . Repeat QUICK TEST  .
  8. Check Internal Harness Continuity  Disconnect internal harness from TFT sensor. Connect positive lead of ohmmeter to tester TFT (+) jack and negative lead to TFT connector Black wire. Measure and record resistance. Connect positive lead of ohmmeter to tester TFT(-) jack and negative lead to TFT connector White wire. If resistances measured are .5 ohm or less, go to next step. If any resistance measured is more than .5 ohm, replace internal harness. Go to step 10).
  9. Check Internal Harness For Shorts To Ground  Using transmission tester, check continuity between each TFT sensor connector terminals and BAT(-) terminal of tester. If continuity does not exist in any circuit, go to next step. If continuity exists in any circuit, replace internal harness. Go to next step.
  10. Check TFT Sensor Resistance  Using ohmmeter, check resistance between terminals TFT sensor. If resistance is within specification for specific temperature, go to next step. If resistances measured are not within specification, replace TFT sensor. Install all components in reverse order of disassembly. Fill transaxle with fluid. Erase all DTCs. See CLEARING CODES  . Repeat QUICK TEST  .
    TFT TEMPERATURE/RESISTANCE

    Temperature °F (°C) Resistance-(K/ohms)
    32-58 (0-20) 37-100
    59-104 (21-40) 16-37
    105-158 (41-70) 5-16
    159-194 (71-90) 2.7-5
    195-230 (91-110) 1.5-2.7
    231-266 (111-130) .8-1.5
    267-322 (131-150) .54-.8
  11. Check TFT Sensor For Short To Ground  Using ohmmeter, check continuity between each TFT sensor terminal and ground. If continuity exists, replace faulty TFT sensor. If continuity does not exist, install all components in reverse order of disassembly. Fill transaxle with fluid. Erase all DTCs. See CLEARING CODES  . Repeat QUICK TEST  , see G -TESTS W/CODES - EEC-V article in the ENGINE PERFORMANCE section to diagnose vehicle harness or PCM malfunctions.
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