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 is connected directly to the powertrain control module (PCM) and consists of the following circuits:

    • The 12-volt reference circuit
    • The low reference circuit
    • The CKP sensor signal circuit

Conditions for Running the DTC

    • DTCs P0101, P0102 , P0103, P0341 are not set.
    • The camshaft position (CMP) sensor is transitioning.
    • The mass air flow (MAF) is more than 3 g/s while cranking.
    • The MAF is more than 5 g/s while running.

Conditions for Setting the DTC

The PCM determines no signal from the CKP sensor for less than 8 seconds.

Diagnostic Aids

Important: 

   • Remove any debris from the PCM connector surfaces before servicing the PCM. Inspect the PCM connector gaskets when diagnosing or replacing the PCM. Ensure that the gaskets are installed correctly. The gaskets prevent contaminant intrusion into the PCM.
   • For any test that requires probing the PCM or component harness connectors, use the connector test adapter kit. Using this kit prevents any damage to the harness connector terminals. Refer to Connector Repairs in Wiring Systems.

The following conditions may cause this DTC to set:

    • Poor connections or terminal tension at the sensor. Refer to Connector Repairs in Wiring Systems.
    • Crankshaft reluctor wheel damage or improper installation.
    • The sensor coming in contact with the reluctor wheel.
    • The engine running out of fuel.

Excess crankshaft end play causes the CKP sensor reluctor wheel to move out of alignment with the CKP sensor. This could result in any one of the following:

    • A no start
    • A start and stall
    • Erratic performance

For an intermittent, refer to Intermittent Conditions .

Test Description

The numbers below refer to the step numbers on the diagnostic table.

  1. This step determines if the fault is present.

  2. This step simulates a CKP sensor signal to the PCM. If the PCM receives the signal, the fuel pump will operate for about two seconds. If the fuel pump operates, the condition is either terminal contact at the CKP sensor, the CKP sensor or, the CKP sensor reluctor wheel.

  3. This test determines if the CKP sensor signal circuit or if the PCM is faulty.

  4. The CKP System Variation Learn Procedure must be performed anytime the relationship between the CKP sensor and the CKP reluctor wheel is changed.

  5. To inspect the reluctor wheel, remove the starter and rotate the crankshaft while viewing the reluctor wheel through the CKP sensor hole. If you cannot determine if the reluctor wheel is damaged, the oil pan may have to be removed.

  6. The CKP System Variation Learn Procedure must be performed anytime the relationship between the CKP sensor and the CKP reluctor wheel is changed.

  7. Before replacing the PCM, inspect the PCM harness connections.

Step

Action

Values

Yes

No

Schematic Reference: Engine Controls Schematics

1

Did you perform the Diagnostic System Check-Engine Controls?

--

Go to Step 2

Go to Diagnostic System Check - Engine Controls

2

Does the engine start and continue to run?

--

Go to Step 3

Go to Step 4

3

  1. Observe the Freeze Frame/Failure Records data 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 as specified in the supporting text or as close to the Freeze Frame/Failure Records data that you observed.

Does the DTC fail this ignition?

--

Go to Step 4

Go to Diagnostic Aids

4

  1. Turn ON the ignition, with the engine OFF.
  2. Lift the vehicle. Refer to Lifting and Jacking the Vehicle in General Information.
  3. Disconnect the crankshaft position (CKP) sensor.
  4. Measure the voltage from the CKP 12 volt reference circuit and a good ground using the DMM .

Does the DMM display the specified value?

B+

Go to Step 5

Go to Step 8

5

Measure the voltage between the CKP sensor 12 volt reference circuit and the CKP sensor low reference circuit using the DMM .

Does the DMM display the specified value?

B+

Go to Step 6

Go to Step 9

6

Momentarily connect the test lamp between the CKP sensor 1 signal circuit and the CKP sensor 12 volt reference circuit.

Does the fuel pump operate when ignition voltage was applied to the CKP sensor 1 signal circuit?

--

Go to Step 11

Go to Step 7

7

Important: Use the connector test adapter kit when probing the PCM connectors. Refer to Connector Repairs in Wiring Systems.

  1. Re-connect the CKP sensor.
  2. Disconnect the PCM connector. Refer to Connector Repairs in Wiring Systems.
  3. Jumper the CKP B+ 12 volt reference circuit at the PCM harness connector to the battery positive voltage terminal using a fused jumper wire. Refer to Connector Repairs in Wiring Systems.
  4. Jumper the CKP low reference circuit at the PCM harness connector to the battery ground terminal.
  5. Probe the CKP sensor signal(1) circuit with the DMM volt scale.
  6. Crank the engine.

Does the DMM indicate that the parameter is within the specified range?

4.0-6.0 V

Go to Step 15

Go to Step 10

8

  1. Test for an open or a short to ground in the CKP 12 volt reference circuit. Refer to Wiring Repairs in Wiring Systems.
  2. If you find an open or a short to ground, repair the circuit as necessary. Refer to Wiring Repairs in Wiring Systems.

Did you find and repair the condition?

--

Go to Step 16

Go to Step 15

9

  1. Test for an open or a poor connection in the CKP low reference circuit. Refer to Wiring Repairs or Connector Repairs in Wiring Systems.
  2. If you find an open or poor connection, repair the condition as necessary. Refer to Wiring Repairs or Connector Repairs in Wiring Systems.

Did you find and repair the condition?

--

Go to Step 16

Go to Step 15

10

  1. Test the CKP sensor(1) signal circuit for the following:
  2. • An open
    • A short to ground
    • A short to voltage
  3. If you find a concern with the signal circuit, repair the circuit as necessary. Refer to Wiring Repairs in Wiring Systems.

Did you find and repair the condition?

--

Go to Step 16

Go to Step 11

11

Important: The CKP System Variation Learn Procedure must be performed anytime the relationship between the CKP sensor and the CKP reluctor wheel is changed. Refer to Crankshaft Position System Variation Learn .

  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 secondary ignition components
  4. If a condition is located, repair as necessary.

Did you find and correct the condition?

--

Go to Step 16

Go to Step 12

12

Visually inspect the CKP sensor reluctor wheel for damage.

Did you find and correct the condition?

--

Go to Step 16

Go to Step 13

13

  1. Inspect for poor connections at the CKP sensor. Refer to Wiring Repairs in Wiring Systems.
  2. If you find a poor connection repair the condition as necessary. Refer to Connector Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 16

Go to Step 14

14

Important: The CKP System Variation Learn Procedure must be performed anytime the relationship between the CKP sensor and the CKP reluctor wheel is changed. Refer to Crankshaft Position System Variation Learn .

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

Did you complete the repair?

--

Go to Step 16

--

15

Replace the PCM. Refer to Powertrain Control Module Replacement .

Did you complete the repair?

--

Go to Step 16

--

16

  1. Operate the scan tool in order to clear the DTCs.
  2. Turn OFF the ignition for 30 seconds.
  3. Start the engine.
  4. Operate the vehicle within the Conditions for Running the DTC as specified in the supporting text.

Does the DTC run and pass?

--

Go to Step 17

Go to Step 2

17

With a scan tool, observe the stored information, Capture Info.

Does the scan tool display any DTCs that you have not diagnosed?

--

Go to Diagnostic Trouble Code (DTC) List

System OK