Leganza SX L4-2.2L DOHC D-TEC MFI (1999)
Neutral Safety Switch: Diagnostic Trouble Code Tests and Associated Procedures
DTC P1520 Park/Neutral Discrete Fault
Circuit Description
The Park/Neutral Position (PNP) Switch contacts close the input circuit from the engine control module (ECM) to ground when the transmission range
switch is in the park or neutral position. The PNP switch is open when a transaxle drive range is selected. The ECM uses the P/N position switch
information to perform the following functions:
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Control idle speed using the Idle Air Control (IAC).
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Vehicle speed sensor (VSS) output.
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Speed sensor diagnostics.
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Ignition coil spark advance.
The ECM supplies 12 volts to the PNP switch signal circuit. The ECM senses a closed switch (PARK or NEUTRAL selected) when the voltage on the
PNP signal switch drops below 1 volt.
Conditions for Setting the DTC
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DTCs P0106, P0107, P0108, P0121, P0122, P0123, P0336, P0337, P0502, P1106, P1121, P1122, P1336 not set.
In park (PNP Switch is ON)
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Vehicle speed is greater than 48 kph (30 mph).
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Engine speed is greater than 2000 rpm.
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Throttle position sensor is greater than 10%.
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Manifold Absolute Pressure (MAP) is greater than 45 kPa.
In gear (PNP Switch is OFF)
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Vehicle speed is greater than 3 kph (2 mph).
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Engine speed is greater than 1100 rpm.
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Throttle position sensor is greater than 0.4%.
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MAP is greater than 40 kPa.
Action Taken When the DTC Sets
The ECM will not illuminate the Malfunction Indicator Lamp (MIL).
The ECM will store conditions which were present when the DTC set as Fail Records data only. This information will be not stored as Freeze Frame
data.
Conditions for Clearing the MIL/DTC
A history DTC P1520 will clear after 40 consecutive warm-up cycles have occurred without a fault.
DTC P1520 can be cleared by using the scan tool or disconnecting the ECM.