GM Service Manual Online
For 1990-2009 cars only

Circuit Description

The crankshaft position (CKP) sensor signal indicates the crankshaft speed and position. The CKP sensor produces a DC voltage of varying amplitude and frequency. The frequency depends on the velocity of the crankshaft, and the DC output voltage depends on crankshaft position and battery voltage. The CKP sensor works in conjunction with a 58-tooth reluctor wheel attached to the crankshaft. The engine control module (ECM) determines the crankshaft position by the reference gap. The ECM can synchronize the ignition timing, fuel injector timing, and spark knock control based on the CKP sensor and the camshaft position (CMP) sensor inputs. The CKP sensor is also used to detect a misfire. The CKP sensor circuits connect directly to the ECM. The circuits between the CKP sensor and ECM consists of the following:

    • A 12-volt reference
    • A low reference
    • A CKP sensor signal

If the ECM detects an incorrect number of CKP sensor signals, DTC P0336 sets.

Conditions for Running the DTC

    • DTCs P0340, P0341, P0345, P0346 are not set.
    • The engine is cranking or running.

Conditions for Setting the DTC

The ECM detects an incorrect number of signals from the CKP sensor.

Action Taken When the DTC Sets

    • The control module illuminates the malfunction indicator lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails.
    • The control module records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the control module stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the control module records the operating conditions at the time of the failure. The control module writes the operating conditions to the Freeze Frame and updates the Failure Records.

Conditions for Clearing the MIL/DTC

    • The control module turns OFF the malfunction indicator lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail.
    • A current DTC, Last Test Failed, clears when the diagnostic runs and passes.
    • A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.
    • Clear the MIL and the DTC with a scan tool.

Step

Action

Yes

No

Schematic Reference: Engine Controls Schematics

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

1

Did you perform the Diagnostic System Check-Vehicle?

Go to Step 2

Go to Diagnostic System Check - Vehicle in Vehicle DTC Information

2

Attempt to start the engine.

Does the engine start and run?

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. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records.

Did the DTC fail this ignition cycle?

Go to Step 4

Go to Intermittent Conditions

4

  1. Turn OFF the ignition.
  2. Remove the fuel injector sight shield. Refer to Fuel Injector Sight Shield Replacement in Engine Mechanical.
  3. Disconnect the 12-way connector.
  4. Test the 12-volt reference circuit for an intermittent condition between the engine control module (ECM) and the 12-way connector. Refer to Testing for Electrical Intermittents and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 17

Go to Step 5

5

Test the low reference circuit for an intermittent condition between the ECM and the 12-way connector. Refer to Testing for Electrical Intermittents and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 17

Go to Step 6

6

Test the crankshaft position (CKP) sensor signal circuit for an intermittent condition between the ECM and the 12-way connector. Refer to Testing for Electrical Intermittents and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 17

Go to Step 7

7

Test for an intermittent and for a poor connection at the ECM side of the 12-way connector. Refer to Testing for Intermittent Conditions and Poor Connections and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 17

Go to Step 8

8

Test for an intermittent and for a poor connection at the ECM. Refer to Testing for Intermittent Conditions and Poor Connections and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 17

Go to Step 9

9

  1. Remove the intake manifold. Refer to Intake Manifold Replacement in Engine Mechanical.
  2. Test the 12-volt reference circuit for an intermittent condition between the CKP sensor and the 12-way connector. Refer to Testing for Electrical Intermittents and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 17

Go to Step 10

10

Test the low reference circuit for an intermittent condition between the CKP sensor and the 12-way connector. Refer to Testing for Electrical Intermittents and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 17

Go to Step 11

11

Test the CKP sensor signal circuit for an intermittent condition between the CKP sensor and the 12-way connector. Refer to Testing for Electrical Intermittents and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 17

Go to Step 12

12

Test for an intermittent and for a poor connection at the CKP sensor side of the 12-way connector. Refer to Testing for Intermittent Conditions and Poor Connections and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 17

Go to Step 13

13

Test for an intermittent and for a poor connection at the CKP sensor. Refer to Testing for Intermittent Conditions and Poor Connections and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 17

Go to Step 14

14

  1. Remove the CKP sensor. Refer to Crankshaft Position Sensor Replacement .
  2. Visually inspect the CKP sensor for the following conditions:
  3. • Physical damage
    • Loose or improper installation
    • Wiring routed too closely to the secondary ignition components
    • Excessive air gap between the CKP sensor and the reluctor wheel
    • The CKP sensor coming in contact with the reluctor wheel
    • Foreign material passing between the CKP sensor and the reluctor wheel

Did you find and correct the condition?

Go to Step 17

Go to Step 15

15

Visually inspect the crankshaft reluctor wheel for following conditions:

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

Refer to Crankshaft and Bearing Cleaning and Inspection in Engine Mechanical.

Did you find and correct the condition?

Go to Step 17

Go to Step 16

16

Replace the CKP sensor. Refer to Crankshaft Position Sensor Replacement .

Did you complete the replacement?

Go to Step 17

 

17

  1. Install the intake manifold. Refer to Intake Manifold Replacement in Engine Mechanical.
  2. Connect the 12-way connector.
  3. Install the fuel injector sight shield. Refer to Fuel Injector Sight Shield Replacement in Engine Mechanical.
  4. Clear the DTCs with a scan tool.
  5. Turn OFF the ignition for 30 seconds.
  6. Start the engine.
  7. Operate the vehicle within the Conditions for Running the DTC. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records.

Did the DTC fail this ignition?

Go to Step 2

Go to Step 18

18

Observe the Capture Info with a scan tool.

Are there any DTCs that have not been diagnosed?

Go to Diagnostic Trouble Code (DTC) List - Vehicle in Vehicle DTC Information

System OK