The crankshaft position (CKP) sensor signal indicates the crankshaft speed and position. The CKP sensor produces an AC voltage of different amplitude and frequency. The frequency depends on the velocity of the crankshaft, and the AC voltage output depends on the crankshaft position and battery voltage. The CKP sensor works in conjunction with a 58X reluctor wheel attached to the crankshaft. The engine control module (ECM) can synchronize the ignition timing, fuel injector timing, and spark knock control based on the CKP and the camshaft position (CMP) sensor inputs. The CKP sensor is also used to detect misfire and tachometer display. The CKP sensor circuits are connected directly to the ECM. The circuits between the CKP sensor and the ECM consist of the following circuits:

The ECM detects greater or less than 58 reference pulses for 10 crankshaft revolutions.

DTC P1321 is a Type C DTC.

DTC P1321 is a Type C DTC.

The following conditions could also set the DTCs:

Schematic Reference

Engine Controls Schematics

Connector End View Reference

Component Connector End Views

Electrical Information Reference

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

Scan Tool Reference

Control Module References for scan tool information

1. Engine running, observe the DTC information with a scan tool. DTC P1321 should not set.
2. Move related harnesses/connectors of the CKP sensor and verify the engine does not stumble, stall, or change engine speed.
3. Operate the vehicle within the Conditions for Running the DTC to verify the DTC does not reset. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records data.

Important: If the CKP sensor lead is damaged in any way, replace the CKP sensor.

1. Ignition OFF, disconnect the harness connector at the CKP sensor.
2. Ignition ON, test for 1.5-2.0 volts between the signal circuit terminal 1 and the low reference circuit terminal 2.

⇒	If less than the specified range, test the circuits for a short to ground or an open/high resistance. If the circuit tests normal, replace the ECM.

⇒	If greater than the specified range, test the circuits for a short to voltage. If the circuit tests normal, replace the ECM.

3. If all circuits test normal, test or replace the CKP sensor.

1. Ignition OFF, disconnect the harness connector at the CKP sensor.

Important: If the CKP sensor lead is damaged in any way, replace the CKP sensor.

2. Connect a DMM between the signal terminal 1 and the low reference terminal 2.
3. Test for 460-620 ohms of resistance between the signal terminal 1 and the low reference terminal 2.

⇒	If not within the specified range, replace the CKP sensor.

4. Disconnect the fuel pump relay.
5. Set the DMM to the AC voltage scale.
6. Engine cranking, test for greater than 1.4 ACV between the signal terminal 1 and the low reference terminal 2.

⇒	If less than the specified range, replace the CKP sensor.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.