Chart C-1A, Park/Neutral Switch - 2.5L TBI W Body

Fig 1: Chart C-1A, Park/Neutral Switch Diagram (2.5L TBI W Body)

Courtesy of GENERAL MOTORS CORP.

ECM supplies ignition voltage through a current limiting resistor to circuit No. 434 and senses a closed switch when voltage on circuit No. 434 drops to less than one volt. ECM uses Park/Neutral signal as one of the inputs to control Idle Air Control (IAC) and Vehicle Speed Sensor (VSS).

1. This test checks for a closed switch to ground in park position. Use an ohmmeter instead of a test light. Resistance will be low indicating continuity to ground.
2. This test checks for an open switch in drive range.
3. Checks to this point indicate the Park/Neutral switch and wiring are okay. ECM signal voltage on circuit No. 434 may be mission. Ensure ECM connector is connected. Disconnect Park/Neutral switch and probe harness connector at circuit No. 434 with voltmeter to ground.

Fig 2: Chart C-1A, Troubleshooting Diagram (2.5L TBI W Body)

Courtesy of GENERAL MOTORS CORP.