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, P0342, or P0343 are not set.
    • The CMP sensor is transitioning.
    • The mass air flow (MAF) is more than 3 g/s.
    • The ignition switch in the Crank mode.

Conditions for Setting the DTC

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

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.

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 the component harness connectors, use the connector test adapter kit. Using this kit prevents any damage to the harness connector terminals. Refer to in Wiring Systems.

The following conditions may cause this DTC to set:

    • Any poor connections or poor terminal tension at the sensor. Refer to in Wiring Systems.
    • Any 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 conditions:

    • 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 and 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 closely as possible to the Freeze Frame and Failure Records conditions.

Does the DTC fail this ignition?

--

Go to Step 4

Go to Diagnostic Aids

4

  1. Turn ON the ignition, leaving the engine OFF.
  2. Lift the vehicle. Refer to in General Information.
  3. Disconnect the crankshaft position (CKP) sensor.
  4. Use a DMM in order to measure the voltage from the CKP ignition feed circuit to a good ground.

Does the voltage equal the specified value?

B+

Go to Step 5

Go to Step 8

5

Use the DMM in order to measure the voltage between the ignition feed circuit and the ground circuit of the CKP sensor.

Does the voltage equal the specified value?

B+

Go to Step 6

Go to Step 9

6

Momentarily connect a test lamp between the signal circuit and the ignition feed circuit of the CKP sensor .

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

--

Go to Step 11

Go to Step 7

7

Important: Use the connector test adapter kit when probing the PCM connectors.

  1. Reconnect the CKP sensor.
  2. Disconnect the PCM connector C1. Refer to Powertrain Control Module Replacement .
  3. Jumper the CKP B+ supply circuit at the PCM harness connector to the battery positive voltage terminal using a fused jumper wire. Refer to Using Fused Jumper Wires in Wiring Systems.
  4. Jumper the CKP ground circuit at the PCM harness connector to the battery ground terminal.
  5. Probe the CKP sensor signal circuit with the DMM set to the 40 volts AC scale.
  6. Crank the engine.

Does the scan tool 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 ignition feed circuit. Refer to Circuit Testing 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 ground circuit. Refer to Testing for Continuity or to Testing for Intermittent Conditions and Poor Connections in Wiring Systems.
  2. If you find an open or poor connection, repair the condition as necessary. Refer to Wiring Repairs or Repairing Connector Terminals to in Wiring Systems.

Did you find and repair the condition?

--

Go to Step 16

Go to Step 15

10

  1. Test the CKP sensor 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.

  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
  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 Testing for Intermittent Conditions and Poor Connections in Wiring Systems.
  2. If you find a poor connection repair the condition as necessary. Refer to Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 16

Go to Step 14

14

  1. Replace the CKP sensor. Refer to Crankshaft Position Sensor Replacement .
  2. Perform the CKP System Variation Learn Procedure. Refer to Crankshaft Position System Variation Learn .

Did you complete the replacement?

--

Go to Step 16

--

15

Replace the PCM. Refer to Powertrain Control Module Replacement .

Did you complete the replacement?

--

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