P1520

CIRCUIT DESCRIPTION

The Park/Neutral Position (PNP) switch is part of the neutral start switch. The PNP switch contacts close the input circuit to the PCM to ground when the transaxle manual shaft is in the park or neutral position. The PNP switch is open when a transaxle drive range is selected. The PCM uses PNP information to perform the following functions:

^ Control idle speed using the IAC.

^ Vehicle Speed Sensor (VSS) Transaxle Output Speed Sensor (TOSS) diagnostics.

^ IC spark advance.

The PCM supplies 12 volts to the PNP input circuit through a current limiting resistor. The PCM senses a closed switch (Park or Neutral selected) when the voltage on the PNP input circuit drops below 1 volt.

CONDITIONS FOR SETTING THE DTC

The signal on the PNP circuit indicates park or neutral not selected (an open PNP switch) during 3 consecutive start-ups.


ACTION TAKEN WHEN THE DTC SETS

^ The PCM will not illuminate the Malfunction Indicator Lamp (MIL).

^ The PCM will store conditions which were present when the DTC set as Fail Records data only. This information will not be stored as Freeze Frame data.


CONDITIONS FOR CLEARING THE MIL/DTC

^ A history DTC will clear after 40 consecutive warm-up cycles have occurred without a malfunction.

^ DTC can be cleared by using the scan tool Clear Info function or by disconnecting the PCM battery feed.

DIAGNOSTIC AIDS

An intermittent may be caused by a poor connection, rubbed through wire insulation or a wire broken inside the insulation. Check for the following conditions:

^ Misadjusted transaxle range switch.

^ Poor connection.

Inspect the PCM and PNP switch harness and connectors for improper mating, broken locks, improperly formed or damaged terminals, and poor terminal to wire connection.

^ Damaged harness.

Inspect the wiring harness for damage. If the harness appears to be OK, disconnect the transaxle range switch 7-way connector, turn ON the ignition switch and observe a voltmeter connected to the PNP circuit at the transaxle range switch 7-way hamess connector while moving connectors and wiring harnesses related to the PNP switch. A change in voltage will indicate the location of the malfunction.

Reviewing the Fail Records vehicle mileage since the diagnostic test last failed may help determine how often the condition that caused the DTC to be set occurs. This may assist in diagnosing the condition.