Century V6-3100 3.1L VIN M SFI (1998)
Performance Shift Switch Malfunction (Part 3 Of 3)
CIRCUIT DESCRIPTION
The performance shift switch allows the driver to select the performance shift mode of the automatic transaxle. The performance shift switch sends
a ground signal to the Body Control Module (BCM) through circuit 1493 when the performance shift switch is on. The performance shift switch
receives ground through circuit 1550.
When the BCM receives a ground signal in circuit 1493, the BCM sends a message through the Class II serial data link indicating that the
performance shift switch is on. This message commands the Instrument Panel Cluster (IPC) to turn on the PERF SHIFT indicator lamp. Also, this
message notifies the Powertrain Control Module (PCM) that the driver selected the performance shift mode.
When the BCM no longer receives a ground signal in circuit 1493, the BCM sends a message through the Class II serial data link indicating that
the performance shift switch is off. This message commands the IPC to turn off the PERF SHIFT indicator lamp. Also, this message notifies the
Powertrain Control Module (PCM) that the driver has turned off the performance shift switch.
DIAGNOSTIC AIDS
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The following conditions may cause an intermittent malfunction to occur:
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An intermittent open or short to ground in circuit 1493.
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An intermittent open in circuit 1550.
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Faulty performance shift switch.
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Poor connections at the BCM.
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Poor connection at the performance shift switch.
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The BCM is open or shorted to ground internally.
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Refer to the Instrument Cluster for the diagnosis and repair of the PERF SHIFT indicator lamp. See: Instrument Panel, Gauges and Warning
Indicators/Instrument Cluster / Carrier
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Refer to the Engine Controls for more information regarding the performance shift mode. See:
TEST DESCRIPTION
Number below refer to the step number on the diagnostic table.
2. Check the BCM for proper operation.
3. Checks the IPC for proper operation.
4. Checks for a malfunction in circuit 1493.
5. Checks for a faulty BCM.
6. Checks for an open in circuit 1550.
7. Determines whether circuit 1493 is open or the performance shift switch is faulty (contacts always open).
8. Determines whether circuit 1493 is shorted to ground or the performance shift switch is faulty (contacts closed all the time).
