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No Upshift To Overdrive

  1. Warm engine to normal operating temperature. With ignition off, disconnect electrical connector from ATCM, located near center console. See Figure .
  2. Road test vehicle and note if transmission upshifts to overdrive once transmission shifts from "L" to "2" and then into "D" range. Reconnect electrical connector. Clear fault codes from ATCM memory, as disconnecting electrical connector may set fault code. See CLEARING FAULT CODES  under TRANSMISSION TESTING. If no overdrive upshift exists, transmission is defective. If overdrive upshift exists, proceed to step 3).
  3. Locate check connector near left strut tower in engine compartment. See Figure . Install Digital Volt-Ohmmeter (DVOM) between cavities No. 3 and 17 of check connector. See Figure . Road test vehicle and ensure voltage increases from zero to 7 volts.
  4. If no voltage exists, obtain access to ATCM, located near center console. See Figure . Note ATCM electrical connector terminal identification. See Figure . Using DVOM, backprobe cavities No. 19 and 20 of ATCM electrical connector with connector installed on ATCM. See Figure .
  5. Check for 10-14 volts with connector installed on ATCM with shift lever in "D" position and ignition on. If 10-14 volts exist, check for defective neutral start switch or wiring circuit. If 10-14 volts does not exist, replace ATCM.
  6. If voltage increases from zero to 3 volts, check for 10-14 volts between cavities No. 19 and 21 of ATCM electrical connector with connector installed, shift lever in "D" position and ignition on. See Figure . If 10-14 volts exist, check for defective neutral start switch or wiring circuit. If 10-14 volts do not exist, replace ATCM.
  7. If voltage increases from 0 to 7 volts, transmission or solenoid is faulty. If voltage increases from 0 to 5 volts, using DVOM, backprobe cavities No. 5 and 19 of ATCM electrical connector with connector installed on ATCM. See Figure .
  8. Turn ignition on. Check voltage with OD switch on shift lever in released (OFF position) and depressed (ON position). No voltage should exist with switch released and 10-14 volts with switch depressed.
  9. If voltage is correct, proceed to step 10). If voltage is not as specified, check for defective OD switch or wiring circuit.
  10. Using DVOM, backprobe cavities No. 17 and 19 of ATCM electrical connector with connector installed on ATCM. See Figure . Voltage should be about 5 volts for Denso system or 12 volts for Aisin system with coolant temperature of 158°F (70°C). If voltage is correct, replace ATCM. If voltage is not correct, proceed to step 11).
    NOTE: Denso or Aisin is the electrical system component manufacturer.
  11. Disconnect electrical connector from cruise control module. Cruise control module is located behind passenger's side kick panel and contains a 18-pin connector. Using DVOM, backprobe cavities No. 17 and 19 of ATCM electrical connector with connector installed on ATCM. See Figure .
  12. Voltage should be about 5 volts for Denso system or 12 volts for Aisin system. If voltage is correct, replace cruise control module.
  13. If voltage is not correct, check for defective wiring between ATCM cavity No. 17 and engine Electronic Control Module (ECM). The engine ECM is located at front of console, near heater case and contains 12-pin, 16-pin and 26-pin connectors.
  14. If wiring is okay, check for pattern select switch and wiring or defective coolant temperature sensor. If pattern select switch, wiring and coolant temperature sensor are okay, replace engine ECM.
    NOTE: If a failure exists with coolant temperature sensor, a Fault Code No. 22 will be set in engine ECM. See appropriate TESTS W/CODES article in the ENGINE PERFORMANCE section:
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