P1C63-NEUTRAL SWITCH RATIONALITY

For a complete wiring diagram, refer to the Wiring Information.

When Monitored:
With the ignition on, zero vehicle speed and during an Auto Start condition.
Set Condition:
The Powertrain Control Module (PCM) detects wheel speed from one or more wheels.

Possible Causes
VEHICLE ROLLS ON IT'S OWN
THE REVERSE SWITCH AND THE NEUTRAL SWITCH HARNESS CONNECTORS ARE REVERSED
(K804) NEUTRAL SWITCH SIGNAL CIRCUIT IS OPEN/HIGH RESISTANCE
(K804) NEUTRAL SWITCH SIGNAL CIRCUIT SHORTED TO GROUND
(Z906) GROUND CIRCUIT OPEN/HIGH RESISTANCE
WHEEL SPEED SENSOR OR VEHICLE SPEED SENSOR READING OUT OF RANGE
FAULTY OR STICKING NEUTRAL SWITCH
POWERTRAIN CONTROL MODULE (PCM)

Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. (Refer to 28 - DTC-Based Diagnostics/MODULE, Powertrain Control (PCM) - Standard Procedure).

1. DTC IS ACTIVE

NOTE: Repair any Vehicle Speed Sensor or Wheel Speed Sensor DTCs that are present before continuing with this test procedure.

1.	Ignition on, engine not running.

2.	With the scan tool, erase DTCs in the PCM.

3.	Test drive the vehicle with Stop/Start mode engaged. Make several complete stops during test drive.

4.	With the scan tool, select View DTCs.

Is the status Active for this DTC?

Yes

Go To 2

Perform the INTERMITTENT DTC diagnostic procedure. (Refer to 28 - DTC-Based Diagnostics/MODULE, Powertrain Control (PCM) - Standard Procedure).

2. CHECK FOR THE REVERSE SWITCH AND THE NEUTRAL SWITCH HARNESS CONNECTORS REVERSED

1.	Turn the ignition off.

2.	Using the wiring diagram as a guide, check for the Reverse Switch and Neutral Switch harness connectors reversed.

Are the Reverse Switch and Neutral Switch harness connectors reversed?

Yes

Change the harness connectors to the proper switches.
Perform the PCM VERIFICATION TEST. (Refer to 28 - DTC-Based Diagnostics/MODULE, Powertrain Control (PCM) - Standard Procedure).

Go To 3

3. CHECK THE (K804) NEUTRAL SWITCH SIGNAL CIRCUIT FOR A SHORT TO GROUND

1.	Turn the ignition off.

2.	Disconnect the Neutral Switch harness connector.

3.	Disconnect the PCM C1 harness connector.

4.	Measure the resistance between ground and the (K804) Neutral Switch Signal circuit at the PCM C1 harness connector.

Is the resistance above 10k Ohms?

Yes

Go To 4

Repair the (K804) Neutral Switch Signal circuit for a short to ground.
Perform the PCM VERIFICATION TEST. (Refer to 28 - DTC-Based Diagnostics/MODULE, Powertrain Control (PCM) - Standard Procedure).

4. CHECK THE (K804) NEUTRAL SWITCH SIGNAL CIRCUIT FOR AN OPEN/HIGH RESISTANCE

1.	Measure the resistance of the (K804) Neutral Switch Signal circuit between the Neutral Switch harness connector and the PCM C1 harness connector.

Is the resistance below 5.0 Ohms?

Yes

Go To 5

Repair the (K804) Neutral Switch Signal circuit for an open or high resistance.
Perform the PCM VERIFICATION TEST. (Refer to 28 - DTC-Based Diagnostics/MODULE, Powertrain Control (PCM) - Standard Procedure).

5. CHECK THE (Z906) GROUND CIRCUIT FOR AN OPEN/HIGH RESISTANCE

1.	Measure the resistance between ground and the (Z906) Ground circuit at the Neutral Switch harness connector.

Is the resistance below 5.0 Ohms?

Yes

Go To 6

Repair the (Z906) Ground circuit for an open or high resistance.
Perform the PCM VERIFICATION TEST. (Refer to 28 - DTC-Based Diagnostics/MODULE, Powertrain Control (PCM) - Standard Procedure).

6. NEUTRAL SWITCH

1.	Replace the Neutral Switch in accordance with the service information.

2.	Reconnect the Neutral Switch harness connector.

3.	Reconnect the PCM C1 harness connector.

4.	Turn the ignition on.

5.	With the scan tool, erase DTCs.

6.	Start the engine and test drive the vehicle.

7.	With the scan tool, select View DTCs.

Did the DTC return?

Yes

Go To 7

Repair complete.
Perform the PCM VERIFICATION TEST. (Refer to 28 - DTC-Based Diagnostics/MODULE, Powertrain Control (PCM) - Standard Procedure).

7. POWERTRAIN CONTROL MODULE

1.	Using the wiring diagram/schematic as a guide, inspect the wiring and connectors between the Neutral Switch and the Powertrain Control Module.

2.	Look for any chafed, pierced, pinched, or partially broken wires.

3.	Look for broken, bent, pushed out or corroded terminals.

4.	Perform any Technical Service Bulletins that may apply.

Were any problems found?

Yes

Repair as necessary.
Perform the PCM VERIFICATION TEST. (Refer to 28 - DTC-Based Diagnostics/MODULE, Powertrain Control (PCM) - Standard Procedure).

Replace the Powertrain Control Module in accordance with the service information.
Perform the PCM VERIFICATION TEST. (Refer to 28 - DTC-Based Diagnostics/MODULE, Powertrain Control (PCM) - Standard Procedure).

P1C63-NEUTRAL SWITCH RATIONALITY

Possible Causes