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Home >> Infiniti >> 2001 >> QX4 RWD >> Repair and Diagnosis >> External Pages >> Different car >> Section 46 (Automatic Transmission Diagnosis - U140E & U140F) >> Diagnostic Tests >> DTC P1780: Park/Neutral Position Switch Circuit Malfunction (Highlander) >> Diagnostic Procedure

Diagnostic Procedure

WARNING: This page does not describe the selected car, but rather 8 other vehicles, including the 2002 Toyota RAV4, 2002 Toyota Highlander, 2002 Toyota Camry, 2002 Lexus RX 300, and 2001 Toyota RAV4. However, it is still accessible from the selected car via links, so may be relevant.
  1. Install scan tool to DLC3 and monitor gearshift position. Move the gearshift lever to the "P", "R", "N", "D", "2" and "L" ranges, and read the NSW, REVERSE, DRIVE, 2ND and LOW signals on the hand-held tester. See Fig 1. If readings are as specified, replace ECM. See appropriate REMOVAL, OVERHAUL & INSTALLATION article in ENGINE PERFORMANCE. If values differ, go to next step.
  2. Remove the neutral start switch. Check for continuity between each terminal shown when the gearshift lever is moved to each range. See Fig 2. If readings are as specified, replace PNP switch. If values differ, go to next step.
  3. Connect the PNP switch connector. Disconnect the ECM connector. Turn ignition on and measure the voltage between terminals "P", "R", "N", "D", "2", and "L" of ECM and terminal E1 when the gearshift lever is placed into specified positions. See Fig 3. If readings are as specified, replace ECM. See appropriate REMOVAL, OVERHAUL & INSTALLATION article in ENGINE PERFORMANCE. If readings are not as specified, repair or replace transaxle wiring harness and connector.
Fig 1: Identifying Scan Tool Gearshift Position Signal Values
G00110677Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
Fig 2: Checking Park/Neutral Position Switch For Continuity
G00110680Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
Fig 3: Checking Wiring Harness For Proper Voltages
G00110678Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
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