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Diagnostic Aids

Perform this test only when directed by QUICK TEST. To prevent replacing good components, check following non-EEC areas for fault:

This test is intended to diagnose following items:

TOT SENSOR (AOD-E) SPECIFICATIONS

Temerature - °F (°C) (1) Volts (1) Ohms
32 (0) 3.88 96,255
41 (5) 3.71 75,201
50 (10) 3.53 59,175
59 (15) 3.32 46,883
68 (20) 3.10 37,387
77 (25) 2.86 30,000
86 (30) 2.62 24,215
95 (35) 2.38 19,657
104 (40) 2.15 16,043
113 (45) 1.92 13,161
122 (50) 1.71 10,050
131 (55) 1.51 8990
140 (60) 1.33 7487
149 (65) 1.17 6265
158 (70) 1.03 5260
167 (75) 0.90 4450
176 (80) 0.78 3775
185 (85) 0.69 3215
194 (90) 0.60 2750
200 (95) 0.52 2361
(1) Value may vary by 15 percent.
Fig 1: Transmission Oil Temperature (TOT) Sensor Circuit
G92D03892
  1. 1) KOEO Code 636  KOEO Code 636 indicate TOT sensor is out of self-test range. Following are possible causes of faults:
    • Incorrect Transmission Fluid Temperature
    • Incorrect Sensor Resistance
    • Faulty ECA

    Ensure transmission fluid temperature is more than 50°F (10°C). Repeat QUICK TEST  . If Code 26/636 is present, go to step 2). If Code 26/636 is not present, test is complete.

  2. 2) Check VREF At Throttle Position Sensor (TPS)  Turn ignition off. Disconnect TPS sensor wiring harness connector. Disconnect 60-pin ECA connector. Inspect terminals and repair if damaged. Install EEC-IV Breakout Box (T83L-50-EEC-IV). Connect ECA to breakout box. Turn ignition on. Measure voltage between VREF and SIG RTN terminals at TPS wiring harness connector. If voltage is 4-6 volts, go to step 3). If voltage is not 4-6 volts, there is a fault in the 5-volt reference circuit. See WIRING DIAGRAM  , or go to CIRCUIT TEST C in TESTS W/CODES - EEC-IV article in ENGINE PERFORMANCE section.
  3. 3) Check TOT Sensor Resistance  Turn ignition off. Disconnect ECA from breakout box. Allow transmission to cool. Turn ignition on. Measure and record voltage between test pin No. 46 and TOT test pin No. 49 at breakout box. Start engine, and warm transmission to normal operating temperature. Disconnect ECA from breakout box. Measure voltage between test pin No. 46 and TOT test pin No. 49 at breakout box. If voltage is within specification, replace ECA, and repeat QUICK TEST  . See TOT SENSOR (AOD-E) SPECIFICATIONS  table. If voltage is not within specification, TOT sensor in transmission is faulty.
    NOTE: A break in step numbering sequence occurs at this point. Procedure skips from step 3) to step 10). No test procedures have been omitted.
  4. 10) KOEO Code 637  KOEO Code 637 indicates TOT sensor output exceeds self-test maximum voltage. Following are possible causes of faults:
    • Transmission Fluid Temperature Incorrect
    • Open Wiring Harness Circuit
    • Faulty ECA

Turn ignition off. Disconnect TOT wiring harness connector. Inspect erminals and repair if damaged. Connect jumper wire between TOT and SIG RTN terminals. Perform KOER SELF-TEST  . If Code 638 is present, fault is in transmission. If Code 638 is not present, go to step 11).

11) Check TOT & SIG RTN Circuit Continuity  Turn ignition off. Leave TOT sensor disconnected. Disconnect 60-pin ECA connector. Inspect terminals and repair if damaged. Install EEC-IV Breakout Box(T83L-50-EEC-IV), leaving ECA disconnected. Measure resistance between TOT circuit at TOT wiring harness connector and TOT test pin No. 49 at breakout box. Measure resistance between SIG RTN circuit at TOT wiring harness connector and TOT test pin No. 49 at breakout box. If either resistance is more than 5 ohms, repair open circuit, and repeat QUICK TEST  . If each resistance is 5 ohms or less, go to step 12).

12) Check TOT Sensor For Short To VPWR  Turn ignition off. Leave ECA and TOT sensor disconnected. Measure resistance between TOT test pin and test pins No. 37 and 57 at breakout box. If resistance is more than 10 k/ohms, replace ECA, and repeat QUICK TEST  . If resistance is 10 k/ohms or less, repair short circuit, and repeat QUICK TEST.

NOTE: A break in step numbering sequence occurs at this point. Procedure skips from step 12) to step 20). No test procedures have been omitted.
  1. 20) KOEO Code 638  KOEO Code 638 indicates TOT sensor output is lower than self-test minimum voltage. Following are possible causes of faults:
    • Damaged TOT Sensor
    • Shorted Wiring Harness Circuit
    • Faulty ECA

    Turn ignition off. Disconnect transmission wiring harness connector. Inspect terminals and repair if damaged. Perform KOEO SELF-TEST  . If Code 637 is present, fault is in transmission. If Code 638 is not present, go to next step.

  2. 21) Check VREF At Throttle Position Sensor (TPS)  Turn ignition off. Disconnect TPS sensor wiring harness connector. Disconnect 60-pin ECA connector. Inspect terminals and repair if damaged. Install EEC-IV Breakout Box (T83L-50-EEC-IV). Connect ECA to breakout box. Turn ignition on. Measure voltage between VREF and SIG RTN terminals at TPS wiring harness connector. See Fig 2 . If voltage is 4-6 volts, go to step 22). If voltage is not 4-6 volts, go to CIRCUIT TEST C in TESTS W/CODES - EEC-IV article in ENGINE PERFORMANCE.
    Fig 2: Identifying Throttle Position Sensor (TPS) Connector Terminals
    G90F10970
  3. 22) Check TOT Sensor Resistance  Turn ignition off. Disconnect ECA from breakout box. Measure resistance between TOT test pin at breakout box and test pins No. 40, 46 and 60. If resistance is more than 10 k/ohms, replace ECA, and repeat QUICK TEST  . If resistance is 10k/ohms or less, repair short circuit, and repeat QUICK TEST.
    NOTE: A break in step numbering sequence occurs at this point. Procedure skips from step 22) to step 25). No test procedures have been omitted.
  4. 25) Check Transmission Wiring Harness  Turn ignition off. Check transmission internal and external wiring and connectors for damage and corrosion. Repair or replace if necessary. If wiring is okay, replace TOT sensor, and repeat QUICK TEST  .
    NOTE: A break in step numbering sequence occurs at this point. Procedure skips from step 25) to step 90). No test procedures have been omitted.
  5. 90) Continuous Memory Code 637/638  Continuous Memory Code 637/638 indicates TOT sensor output is lower than during previous 80 warm-up cycles; a fault has been detected in TOT circuit. Following are possible causes of faults:
    • Intermittent Fault In TOT Sensor
    • Intermittent Short Or Open In Wiring Harness

Turn ignition off. Disconnect 60-pin ECA connector. Inspect terminals and repair if damaged. Install EEC-IV Breakout Box (T83L-50-EEC-IV). Connect ECA to breakout box. Connect DVOM between test pins No. 2 and 46 at breakout box. Turn ignition on. Shake and bend TOT and SIG RTN wires between transmission and ECA. Voltage should remain stable or change gradually. If voltage drops or surges abruptly, fault in circuit is indicated. If fault is indicated, isolate and repair as necessary. If no faults are found, problem cannot be located at this time.

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