GM Service Manual Online
For 1990-2009 cars only

Circuit Description

The crankshaft position (CKP) sensor is a 24X sensor. It provides 24 digital ON/OFF signals to the powertrain control module (PCM) per revolution of the crankshaft. This information is used by the PCM for ignition timing, fuel injector timing, misfire diagnostics, and tachometer display. The PCM supplies 12 volts to the sensor on the 12-volt reference circuit, and provides a ground on the low reference circuit. The CKP sensor provides signals to the PCM on the medium resolution engine speed signal circuit. The PCM monitors the CKP sensor for errors. If the PCM does not receive a signal from the CKP sensor, DTC P0335 sets.

DTC Descriptor

This diagnostic procedure supports the following DTC:

DTC P0335 Crankshaft Position (CKP) Sensor Circuit

Conditions for Running the DTC

    • The camshaft position (CMP) sensor signal is incrementing.
    • The mass air flow (MAF) is more than 2 g/s.
    • The engine is cranking or running.
    • The diagnostic runs continuously when the above conditions are met.

Conditions for Setting the DTC

The PCM has detected no CKP sensor pulses for more than 2 seconds.

Action Taken When the DTC Sets

    • The control module illuminates the malfunction indicator lamp (MIL) when the diagnostic runs and fails.
    • The control module records the operating conditions at the time the diagnostic fails. The control module stores this information in the Freeze Frame/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.

Test Description

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

  1. An internally shorted CMP sensor, CKP sensor or a short to ground on either 12-volt reference circuit will set DTCs P0335 and P0340.

  1. This step tests for high resistance in the 12-volt reference circuit and the low reference circuit.

  1. Any change in RPM verifies that the controller is able to receive a signal.

Step

Action

Values

Yes

No

Schematic Reference: Engine Controls Schematics

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

1

Did you perform the Diagnostic System Check - Vehicle?

--

Go to Step 2

Go to Diagnostic System Check - Vehicle

2

Attempt to start the engine.

Does the engine start and run?

--

Go to Step 3

Go to Step 4

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?

--

Go to Step 4

Go to Testing for Intermittent Conditions and Poor Connections

4

  1. Turn ON the ignition, with the engine OFF.
  2. Raise the vehicle. Refer to Lifting and Jacking the Vehicle .
  3. Test for an intermittent and for a poor connection at the crankshaft position (CKP) sensor. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs .

Did you find and correct the condition?

--

Go to Step 26

Go to Step 5

5

  1. Disconnect the CKP sensor.
  2. Measure the voltage from the 12-volt reference circuit of the CKP sensor to a good ground with a DMM.

Is the voltage measured within 1 volt of the specified value?

B+

Go to Step 7

Go to Step 6

6

Observe the DTC Info with a scan tool.

Is DTC P0340 also set?

--

Go to Step 11

Go to Step 14

7

Measure the voltage from the 12-volt reference circuit to the low reference circuit of the CKP sensor with a DMM.

Is the voltage measured within 1 volt of the specified value?

B+

Go to Step 8

Go to Step 15

8

  1. Turn OFF any electrical loads or accessories.
  2. Measure the amperage between the 12-volt reference circuit and the low reference circuit of the CKP sensor with a DMM.

Is the amperage more than the specified value?

250 mA

Go to Step 9

Go to Step 16

9

  1. Connect a test lamp to a battery positive voltage source.
  2. Probe the medium resolution engine speed signal circuit with the test lamp at the harness connector.

Does the test lamp illuminate?

--

Go to Step 18

Go to Step 10

10

  1. Tap the medium resolution engine speed signal circuit with the test lamp repeatedly at the harness connector.
  2. Observe the 24X Crank Sensor parameter with the scan tool.

Does the RPM change?

--

Go to Step 12

Go to Step 19

11

  1. Observe the DMM that is still connected between the 12-volt reference circuit of the CKP sensor and a good ground.
  2. Disconnect the camshaft position (CMP) sensor.

Does the voltage change?

--

Go to Step 23

Go to Step 13

12

  1. Jumper the low reference circuit and the 12-volt reference circuit of the CKP sensor to the CKP harness connector with the J 35616 Terminal Test Kit. Refer to Circuit Testing .
  2. Measure the D.C. duty cycle from the medium resolution engine speed signal terminal at the CKP sensor to a good ground with a DMM. Refer to Circuit Testing .
  3. Crank the engine.

Does the DMM display the specified value?

OL

Go to Step 20

Go to Testing for Intermittent Conditions and Poor Connections

13

Test the 12-volt reference circuit of the CKP sensor and the CMP sensor for a short to ground. Refer to Circuit Testing .

Did you find and correct the condition?

--

Go to Step 26

Go to Step 25

14

Test the 12-volt reference circuit of the CKP sensor for an open. Refer to Circuit Testing .

Did you find and correct the condition?

--

Go to Step 26

Go to Step 22

15

Test the low reference circuit of the CKP sensor for an open. Refer to Circuit Testing and Wiring Repairs .

Did you find and correct the condition?

--

Go to Step 26

Go to Step 22

16

Test the 12-volt reference circuit of the CKP sensor for high resistance. Refer to Circuit Testing and Wiring Repairs .

Did you find and correct the condition?

--

Go to Step 26

Go to Step 17

17

Test the low reference circuit of the CKP sensor for high resistance. Refer to Circuit Testing and Wiring Repairs .

Did you find and correct the condition?

--

Go to Step 26

Go to Step 22

18

Test the medium resolution engine speed signal circuit for a short to ground. Refer to Circuit Testing and Wiring Repairs .

Did you find and correct the condition?

--

Go to Step 26

Go to Step 25

19

Test the medium resolution engine speed signal circuit for an open or for a short to voltage. Refer to Circuit Testing and Wiring Repairs .

Did you find and correct the condition?

--

Go to Step 26

Go to Step 22

20

  1. Remove the CKP sensor. Refer to Crankshaft Position Sensor Replacement .
  2. Visually 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
    • Electromagnetic interference in the CKP sensor circuits

Did you find and correct the condition?

--

Go to Step 26

Go to Step 21

21

Inspect the reluctor wheel for the following conditions:

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

Did you find and correct the condition?

--

Go to Step 26

Go to Step 24

22

Test for an intermittent and for a poor connection at the powertrain control module (PCM). Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs .

Did you find and correct the condition?

--

Go to Step 26

Go to Step 25

23

Replace the CMP sensor. Refer to Camshaft Position Sensor Replacement .

Did you complete the replacement?

--

Go to Step 26

--

24

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

Did you complete the replacement?

--

Go to Step 26

--

25

Replace the PCM. Refer to Control Module References for replacement, setup, and programming.

Did you complete the replacement?

--

Go to Step 26

--

26

  1. Lower the vehicle.
  2. Clear the DTCs with a scan tool.
  3. Turn OFF the ignition for 30 seconds.
  4. Start the engine.
  5. 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 27

27

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

System OK