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Home >> Toyota >> 2001 >> Sienna CE >> Repair and Diagnosis >> External Pages >> Different car >> Section 67 (Automatic Transmission Diagnosis - A340E, A340F) >> Diagnostic Tests >> P1783: Transfer Neutral Position Switch Malfunction >> Diagnostic Procedure

Diagnostic Procedure

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  1. Check the PNP switch operation. See PARK/NEUTRAL POSITION SWITCH  under COMPONENT TESTS. If the PNP switch tests okay, go to next step. If not, replace the PNP switch.
  2. Remove the transfer neutral position switch. Check for continuity when ball is pushed in. See Figure. Release the ball. There should be no continuity. If switch operates as specified, replace the transfer neutral position switch switch. If not, go to next step.
  3. Check the combination meter. See appropriate INSTRUMENT PANELS articles in ACCESSORIES & EQUIPMENT. If the combination meter checks okay, go to next step. If not replace the combination meter.
  4. Remove the ECM with the connectors still connected. Turn the ignition switch to the ON position. Measure the voltage between terminal TFN of the ECM and ground when the transfer case gearshift lever is shifted into the Neutral position. See PIN VOLTAGE TESTS . Voltage should be less than 1.5 volts, and when in except TFN position, voltage should be 9-14 volts. If voltage is not as specified, go to next step. If voltage is within specifications, see SYMPTOM DIAGNOSIS  under TROUBLE SHOOTING.
  5. Check for an open or shorted condition in the harness and connector between transfer neutral position switch and ECM. If a problem was found, repair or replace the wiring harness and connector. If no problem was found, replace the ECM. See appropriate REMOVAL, OVERHAUL & INSTALLATION article in ENGINE PERFORMANCE.
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