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 works in conjunction with a 58-rib reluctor ring attached to the crankshaft in which two ribs are missing, 60 minus 2 ring. The engine control module (ECM) synchronizes the crankshaft position by the reference gap which is created by the two missing ribs. The CKP sensor circuits are connected directly to the ECM. The circuits between the CKP sensor and the ECM consists of the following:

    • A CKP sensor high
    • A CKP sensor low
    • A shielded ground

If the ECM has detected less than 58 reference pulses, DTC P0337 sets.

Conditions for Running the DTC

    • The engine is cranking or running.
    • DTCs P0341, P0342, P0343 are not set.

Conditions for Setting the DTC

The ECM has detected less than 58 CKP reference pulses.

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.

Test Description

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

  1. This step tests for resistance of the CKP sensor and its lead.

  2. This step inspects for electromagnetic interference in any of the CKP circuits.

Step

Action

Values

Yes

No

Schematic Reference: Engine Controls Schematics

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

1

Did you perform the Diagnostic System Check-Engine Controls?

--

Go to Step 2

Go to Diagnostic System Check - Engine Controls

2

Important: If DTC P0335 sets, diagnose this DTC first.

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.

Does the DTC fail this ignition?

--

Go to Step 4

Go to Intermittent Conditions

4

Inspect all of the circuits going to the CKP sensor for the following:

    • Routed too closely to other wiring or components
    • Routed too closely to after-market add- on electrical equipment
    • Routed too closely to solenoids, relays, and motors

Did you find and correct the condition?

--

Go to Step 13

Go to Step 5

5

  1. Disconnect the Engine Control Module (ECM) harness connector.
  2. Measure the resistance from the high circuit of the CKP sensor and the low circuit of the CKP sensor with a DMM.

Is the resistance within the specified range?

700-1100 ohms

Go to Step 9

Go to Step 6

6

Test the CKP Sensor High Circuit for an open or high resistance.

Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

 

Go to Step 13

Go to Step 7

7

Inspect for poor connections at the CKP sensor harness connector. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 13

Go to Step 8

8

Inspect for poor connections at the engine control module (ECM). Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 13

Go to Step 9

9

Important: If the sensor lead is damaged in any way, DO NOT repair the lead.

  1. Remove the CKP sensor. Refer to Crankshaft Position Sensor Replacement .
  2. Inspect the CKP sensor and the harness for the following conditions:
  3. • Physical damage
    • Excessive play or looseness
    • Improper installation
    • Foreign material passing between the CKP sensor and the reluctor ring
    • Electromagnetic interference in the CKP sensor circuits
    • Excessive air gap between the CKP sensor and the reluctor ring

Did you find and correct the condition?

--

Go to Step 13

Go to Step 10

10

Inspect the reluctor ring for the following conditions:

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

Refer to Diagnostic Aids and Crankshaft and Bearing Removal in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 13

Go to Step 11

11

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

Did you find and correct the condition?

--

Go to Step 13

Go to Step 12

12

Replace the ECM. Refer to Engine Control Module Replacement .

Did you find and correct the condition?

--

Go to Step 13

--

13

  1. Clear the DTCs with a scan tool.
  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 2

Go to Step 14

14

Observe the Capture Info with a scan tool.

Are there any DTCs that have not been diagnosed?

--

Go to Diagnostic Trouble Code (DTC) List

System OK