GM Service Manual Online
For 1990-2009 cars only

Object Number: 337318  Size: SF
Engine Controls Component Views
Cell 21: P100, Camshaft Position Sensor, Crankshaft Position Sensor, and Knock Sensors
OBD II Symbol Description Notice
Handling ESD Sensitive Parts Notice

Circuit Description

The Crankshaft Position Sensor CKP is mounted in the right rear of the engine block above the starter. The CKP sensor works in conjunction with a 24X reluctor wheel mounted on the rear of the crankshaft. The CKP sensor has a B+ power supply, a ground, and a signal circuit.

As the crankshaft rotates, the reluctor wheel teeth interrupt a magnetic field produced by a magnet within the sensor. The sensor's internal circuitry detects this and produces a signal which the PCM reads. The PCM uses this signal to accurately measure crankshaft velocity which is a variable used in order to detect misfire. The PCM also uses the signal to control spark and fueling.

Conditions for Running the DTC

    • DTCs P0101, P0102 , P0103, P0341, P0342, P0343 are not set.
    • The CMP sensor is transitioning.
    • The MAF is greater 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 3 seconds.

Action Taken When the DTC Sets

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

Conditions for Clearing the MIL/DTC

    • The PCM turns OFF the malfunction indicator lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail.
    • A last test failed, or current DTC, clears when the diagnostic runs and does not fail.
    • A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.
    • Use a scan tool in order to clear the MIL and the DTC.

Diagnostic Aids

Important: Remove any debris from the PCM connector surfaces before servicing the PCM. Inspect the PCM connector gaskets when diagnosing/replacing the PCM. Ensure that the gaskets are installed correctly. The gaskets prevent water intrusion into the PCM.

The following problems may cause this DTC to set:

    • Poor connections/terminal tension at the sensor
    • Crankshaft reluctor wheel damage or improper installation
    • The sensor coming in contact with the reluctor wheel
    • The engine running out of fuel.

Using Freeze Frame and/or Failure Records data may aid in locating an intermittent condition. If you cannot duplicate the DTC, the information included in the Freeze Frame and/or Failure Records data can aid in determining how many miles since the DTC set. The Fail Counter and Pass Counter can also aid determining how many ignition cycles the diagnostic reported a pass and/or a fail. Operate the vehicle within the same freeze frame conditions (RPM, load, vehicle speed, temperature etc.) that you observed. This will isolate when the DTC failed. For an intermittent condition, refer to Symptoms .

Excess crankshaft end play will cause 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 Symptoms .

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. Refer to Crankshaft Position System Variation Learn .

  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. Refer to Crankshaft Position System Variation Learn .

  7. Before replacing the PCM, inspect the PCM harness connections. Refer to Intermittents and Poor Connections Diagnosis in Wiring Systems.

  8. The repair is not complete if the scan tool indicates that the diagnostic ran and failed.

Step

Action

Value(s)

Yes

No

1

Did you perform the Powertrain On-Board Diagnostic (OBD) System Check?

--

Go to Step 2

Go to Powertrain On Board Diagnostic (OBD) System Check

2

Does the engine start and continue to run?

--

Go to Step 3

Go to Step 4

3

  1. Turn ON the ignition leaving the engine OFF.
  2. Review the Freeze Frame and/or Failure Records data for this DTC and record or document the parameters.
  3. Turn OFF the ignition for 15 seconds.
  4. Start the engine.
  5. Operate the vehicle within the conditions required for this diagnostic to run, and as close to the conditions recorded in Freeze Frame/Failure Records as possible. Special operating conditions that you need to meet before the PCM will run this diagnostic , where applicable, are listed in Conditions for Running the DTC.
  6. Select the Specific DTC option under the Diagnostic Trouble Code (DTC) option using a scan tool.

Does the scan tool indicate that this diagnostic failed this ignition?

--

Go to Step 4

Go to Diagnostic Aids

4

Caution: Before proceeding, remove the fuses for the ignition coil and fuel injector feed circuits in order to prevent personal injury from engine rotation, sparks, and excessive engine fueling.

  1. Turn ON the ignition leaving 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. Connect the test lamp J 35616-200 to a known good ground.
  5. Probe the CKP sensor ignition feed circuit at the PCM side of the CKP sensor harness connector. Refer to Probing Electrical Connectors in Wiring Systems.

Is the test lamp illuminated?

--

Go to Step 5

Go to Step 8

5

Connect the test lamp J 35616-200 between the CKP sensor ignition feed circuit and the CKP sensor ground circuit.

Is the test lamp illuminated?

--

Go to Step 6

Go to Step 9

6

Momentarily connect the test lamp J 35616-200 between the CKP sensor signal circuit and the CKP sensor ignition feed circuit.

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

--

Go to Step 11

Go to Step 7

7

Important: Use the connector test adapter kit J 35616 when probing the PCM connectors. Refer to Using Connector Test Adapters in Wiring Systems.

  1. Re-connect the CKP sensor.
  2. Disconnect the PCM connector C1 located on the same side as the manufacturer's logo. Refer to Powertrain Control Module Replacement/Programming .
  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 J 39200 set to the 40V AC scale.
  6. Crank the engine.

Is the voltage within the specified range?

4.0-6.0V

Go to Step 15

Go to Step 10

8

Test for an open or a short to ground in the CKP ignition feed circuit.

Did you find and repair the condition?

--

Go to Step 16

Go to Step 15

9

Test for an open or a poor connection in the CKP ground circuit. Refer to Intermittents and Poor Connections Diagnosis in Wiring Systems.

Did you find and repair the condition?

--

Go to Step 16

Go to Step 15

10

Test the CKP sensor signal circuit for the following:

    • An open
    • A short to ground
    • A short to voltage

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 .

Remove the CKP sensor. Refer to Crankshaft Position Sensor Replacement . Visually inspect the CKP Sensor for the following conditions:

    • Physical damage
    • Loose or improper installation
    • Wiring routed too closely to secondary ignition components

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 Intermittents and Poor Connections Diagnosis in Wiring Systems.
  2. If you find a poor connection repair the terminal as necessary. Refer to Repairing Connector Terminals 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 .

Is the action complete?

--

Go to Step 16

--

15

Important:: Program the replacement PCM. Refer to Powertrain Control Module Replacement/Programming .

Replace the PCM.

Is the action complete?

--

Go to Step 16

--

16

  1. Select the Diagnostic Trouble Codes (DTC) option and the Clear DTC Information option using the scan tool.
  2. Idle the engine at the normal operating temperature.
  3. Select the Specific DTC option under the Diagnostic Trouble Code (DTC) option using a scan tool.
  4. Operate vehicle within the Conditions for Running the DTC as specified in the supporting text, if applicable.

Does the scan tool indicate that this test passed?

--

Go to Step 17

Go to Step 2

17

Select the Capture Info option and the Review Info option using the scan tool.

Are any DTCs displayed that you have not diagnosed?

--

Go to the applicable DTC table

System OK