GM Service Manual Online
For 1990-2009 cars only

Circuit Description

The crankshaft position (CKP) sensor is a hall-effect sensor which senses a slotted wheel that is attached to the crankshaft. The slotted wheel interrupts a magnetic field and produces a reference signal from the sensor.

Conditions for Setting the DTC

    • There are consecutive missing pulses of 10 or more.
    • The starting manifold absolute pressure (MAP) drop is less than 0.6 kPa (0.09 psi) for at least 3 seconds.
    • The starting battery voltage is less than 0.8 volts for at least 3 seconds.
    • The revolutions of the 58x signal is less than 65.

Diagnostic Aids

Inspect for poor connections at the electronic control module (ECM) and at the crankshaft position (CKP) sensor.

Step

Action

Values

Yes

No

1

Was the Diagnostic System Check performed?

--

Go to Step 2

Go to Diagnostic System Check - Engine Controls

2

Start the engine and allow it to idle.

Does the engine start?

--

Go to Step 3

Go to Engine Cranks but Does Not Run

3

  1. Turn the ignition to LOCK.
  2. Disconnect the crankshaft position (CKP) sensor connector.
  3. Inspect the CKP sensor terminals.

Are any terminals damaged?

--

Go to Step 13

Go to Step 4

4

Inspect the CKP sensor connector terminals.

Are any connector terminals damaged?

--

Go to Step 5

Go to Step 6

5

  1. Repair or replace any damaged terminals.
  2. Clear any DTCs from the engine control module (ECM).
  3. Road test the vehicle.
  4. Perform the Diagnostic System Check.

Did you complete the repair?

--

System OK

--

6

  1. Connect the CKP sensor connector.
  2. Disconnect the electronic ignition (EI) system ignition coil connector to prevent the vehicle from starting.
  3. Connect a voltmeter between ground and the ECM connector terminal A16 by backprobing the ECM connector.

Are the voltage readings near the values specified?

1.08 V with the ignition ON, 1.2 V during cranking

Go to Step 7

Go to Step 9

7

Connect a voltmeter between ground and the ECM connector terminal B14 by backprobing the ECM connector.

Are the voltage readings near the values specified?

1.08 V with the ignition ON, 1.2 V during cranking

Go to Step 8

Go to Step 10

8

  1. Connect the EI system ignition coil connector.
  2. Replace the ECM. Refer to Engine Control Module Replacement .
  3. Road test the vehicle.
  4. Perform the Diagnostic System Check.

Did you complete the repair?

--

System OK

--

9

Inspect for an open or short in the wire between the CKP sensor connector terminal 1 and the ECM connector terminal B14.

Is the problem found?

--

Go to Step 12

Go to Step 11

10

Inspect for an open or short in the wire between the CKP sensor connector terminal 2 and the ECM connector terminal A16.

Is the problem found?

--

Go to Step 12

Go to Step 11

11

Inspect for an open or short in the wire between the CKP sensor connector terminal 3 and ground.

Is the problem found?

--

Go to Step 12

Go to Step 13

12

  1. Connect the EI system ignition coil connector.
  2. Repair the wiring as needed.
  3. Clear any DTCs from the ECM.
  4. Road test the vehicle.
  5. Perform the Diagnostic System Check.

Did you complete the repair?

--

System OK

--

13

  1. Connect the EI system coil connector.
  2. Replace the CKP sensor. Refer to Crankshaft Position Sensor Replacement .
  3. Clear any DTCs from the ECM.
  4. Road test the vehicle.
  5. Perform the Diagnostic System Check.

Did you complete the repair?

--

System OK

--