Circuit Description
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 consists of the following circuits:
| • | A CKP sensor high reference |
| • | A CKP sensor low reference |
| • | A shielded ground |
If the ECM detects an incorrect number of CKP pulses from the CKP sensor, this DTC sets.
DTC Descriptor
This diagnostic procedure supports the following DTC:
DTC P1321 Crankshaft Position (CKP) Reluctor Wheel Performance.
Conditions for Running the DTC
| • | The engine is running. |
| • | The number of extra or missing teeth is more than or equal to 2 per revolution. |
| • | DTC P1321 runs continuously once the above conditions are met. |
Conditions for Setting the DTC
The ECM detects more or less than 58 reference pulses for 10 crankshaft revolutions.
Action Taken When the DTC Sets
| • | The malfunction indicator lamp (MIL) will illuminate after 3 consecutive trips with a fail. |
| • | The ECM will record operating conditions at the time the diagnostic fails. This information will be stored in the Freeze Frame and Failure Records buffers. |
Conditions for Clearing the MIL/DTC
| • | The MIL will turn OFF after 4 consecutive ignition cycles in which the diagnostic runs without a fault. |
| • | DTCs can be cleared by using the scan tool. |
| • | Disconnect the ECM battery feed for more than 10 seconds. |
Test Description
The numbers below refer to the step numbers on the diagnostic table.
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This step is testing for a poor connection at the components and for an intermittent condition with the wiring. Clearing the DTCs allows the ECM to synchronize the cam and crank reference pulses.
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This step is testing for Electromagnetic interference (EMI). If the CKP sensor circuits are routed close to high load circuits or components, this DTC may set.
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This step is testing for an ECM condition. The ECM uses a pull-up voltage of 1.8 volts on each CKP sensor circuit to reduce noise interference from EMI. If the voltage is not present, replace the ECM.
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This step is testing for an ECM condition. The ECM uses a pull-up voltage of 1.8 volts on each CKP sensor circuit to reduce noise interference from EMI. If the voltage is not present, replace the ECM.
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This step tests for a condition in the CKP sensor shielded ground circuit. Normal EMI could effect the out-put signal of the CKP sensor if an open or high resistance exists.
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Missing, damaged, or broken teeth on the reluctor wheel can set this DTC. If the crankshaft was recently replaced or the vehicle/engine is new and this DTC is set, inspect all teeth on the reluctor wheel.
Step | Action | Values | Yes | No | ||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
Schematic Reference: Engine Controls Schematics Connect End View Reference: Engine Controls Connector End Views | ||||||||||||||
1 | Did you perform the Diagnostic System Check - Engine Controls? | -- | Go to Step 2 | |||||||||||
2 |
Did DTC P1321 fail this ignition? | -- | Go to Step 4 | Go to Step 3 | ||||||||||
3 |
Did the DTC fail this ignition? | -- | Go to Step 4 | Go to Intermittent Conditions | ||||||||||
4 | Is DTC P0335, P0336, or P0337 also set? | -- | Go to Step 5 | |||||||||||
Does the engine stumble or stall when moving the harnesses and connectors? | -- | Go to Step 14 | Go to Step 6 | |||||||||||
Did you find and correct the condition? | -- | Go to Step 18 | Go to Step 7 | |||||||||||
Is the voltage within the specified range? | 1.5-2.0 DCV | Go to Step 8 | Go to Step 13 | |||||||||||
Measure the voltage between the high reference circuit of the CKP sensor and a good ground with a DMM. Is the voltage within the specified range? | 1.5-2.0 DCV | Go to Step 9 | Go to Step 13 | |||||||||||
Is the resistance less than the specified value? | 5 ohms | Go to Step 10 | Go to Step 15 | |||||||||||
10 |
Important: If the sensor lead is damaged in any way, DO NOT repair the lead.
Did you find and correct the condition? | -- | Go to Step 18 | Go to Step 11 | ||||||||||
|
Important: If the reluctor wheel is also damaged, replace the CKP sensor and the crankshaft. Inspect the reluctor wheel for the following conditions:
Did you find and correct the condition? | -- | Go to Step 18 | Go to Step 12 | |||||||||||
12 | Test for an intermittent and for a poor connection at the CKP sensor. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairsin Wiring Systems. Did you find and correct the condition? | -- | Go to Step 18 | Go to Step 16 | ||||||||||
13 | Test for an intermittent and for a poor connection at the ECM. Refer to Testing for Intermittent Conditions and Poor Connectionsand Connector Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 18 | Go to Step 17 | ||||||||||
14 | Repair the intermittent condition in the CKP sensor circuits. Refer to Wiring Repairsin Wiring Systems. Did you complete the repair? | -- | Go to Step 18 | -- | ||||||||||
15 | Repair the open or high resistance in the engine ground shield. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | -- | Go to Step 18 | -- | ||||||||||
16 | Replace the CKP sensor. Refer to Crankshaft Position Sensor Replacement. Did you complete the replacement? | -- | Go to Step 18 | -- | ||||||||||
17 | Replace the ECM. Refer to Engine Control Module Replacement . Did you complete the replacement? | -- | Go to Step 18 | -- | ||||||||||
18 |
Did the DTC fail this ignition? | -- | Go to Step 2 | Go to Step 19 | ||||||||||
19 | Are there any DTCs that have not been diagnosed? | -- | System OK | |||||||||||
