GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Chevrolet 🢒 2005 🢒 Optra 🢒 Engine 🢒 Engine Controls - 1.6L (L91) 🢒 DTC P1321

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.

  1. 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.

    2.

  2. 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.

  3. 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.

    4.

  4. 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.

    5.

  5. 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.

    6.

  6. 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

Connector End View Reference: Engine Control Module Connector End Views or Engine Controls Connector End Views

1

Did you perform the Diagnostic System Check - Engine Controls?

--

Go to Step 2

Go to Diagnostic System Check - Engine Controls

2
  1. Start the engine.
  2. Observe the DTC Info with a scan tool.

Did DTC P1321 fail this ignition?

--

Go to Step 4

Go to Step 3

3
  1. Observe the Freeze Frame/Failure Records for this DTC.
  2. Turn OFF the ignition for 30 seconds.
  3. Start the engine.
  4. Operate the vehicle within the Conditions for Running the DTC.

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 Diagnostic Trouble Code (DTC) List

Go to Step 5

5

  1. Start the engine.
  2. Allow the engine to idle.
  3. Move the related harnesses and connectors for the CKP sensor from the engine control module (ECM) to the CKP sensor.

Does the engine stumble or stall when moving the harnesses and connectors?

--

Go to Step 14

Go to Step 6

6

  1. Turn OFF the ignition.
  2. Inspect the crankshaft position (CKP) sensor circuits for the following conditions:
    3. • Routed too close to the battery or the battery cables
    • Routed too close to other wiring or components
    • Routed too close to after market add on electrical equipment
    • Routed too close to solenoids, relays, and motors

Did you find and correct the condition?

--

Go to Step 18

Go to Step 7

7

  1. Disconnect the CKP sensor.
  2. Turn ON the ignition, with the engine OFF.
  3. Measure the voltage between the low 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 8

Go to Step 13

8

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

9

  1. Turn OFF the ignition.
  2. Disconnect the ECM.
  3. Measure the resistance between the shielded ground circuit of the CKP sensor, at the ECM connector, and a good ground.

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.

  1. Remove the CKP sensor. Refer to Crankshaft Position Sensor Replacement .
  2. Inspect the CKP sensor for the following conditions:
    3. • Physical damage
    • Excessive play or looseness
    • Improper installation
    • Foreign material passing between the CKP sensor and the reluctor wheel
    • Excessive air gap between the CKP sensor and the reluctor wheel

Did you find and correct the condition?

--

Go to Step 18

Go to Step 11

11

Important: If the reluctor wheel is also damaged, replace the CKP sensor and the crankshaft.

Inspect the reluctor wheel for the following conditions:

    • Physical damage
    • Improper installation
    • Excessive end play or looseness

Refer to Crankshaft Replacement in Engine Mechanical - 1.6L (L91).

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 Repairs in 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 Connections and 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 Repairs in 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
  1. Clear the DTCs with a scan tool.
  2. Turn OFF the ignition for 30 seconds.
  3. Start the engine.
  4. Operate the vehicle within the Conditions for Running the DTC.

Did the DTC fail this ignition?

--

Go to Step 2

Go to Step 19

19

Are there any DTCs that have not been diagnosed?

--

Go to Diagnostic Trouble Code (DTC) List

System OK