For 1990-2009 cars
Engine Controls Component Views
Engine Controls Schematics

### Circuit Description

The crankshaft position (CKP) sensor is a variable reluctance sensor. The crankshaft position (CKP) sensor indicates the crankshaft speed and position. The CKP sensor produces an AC voltage of different amplitude and frequency. The frequency depends on the velocity of the crankshaft. The AC voltage output depends on the crankshaft position and battery voltage. The CKP sensor works in conjunction with a 7X reluctor wheel attached to the crankshaft. The CKP sensor connects to the powertrain control module (PCM) through the following circuits:

• | The CKP sensor signal

• | The low reference

Step | Action | Value(s) | 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-Engine Controls? | -- | Go to Step 2 | Go to Diagnostic System Check - Engine Controls
2 | Attempt to start the engine. Does the engine start and run? | -- | Go to Step 3 | Go to Step 4
3 |

1. Turn OFF the ignition.
2. Disconnect the powertrain control module (PCM).
3. Measure the resistance between the signal circuit and the low reference circuit of the crankshaft position (CKP) sensor with a DMM. Refer to Circuit Testing in Wiring Systems.

Is the resistance within the specified range?

500-900 ohms

Go to Intermittent Conditions

Go to Step 11

4 |

1. Crank the engine.
2. Observe the CMP Resync Counter parameter with a scan tool.

Does the CMP Resync Counter increment?

--

Go to Step 12

Go to Step 5

5 | Test the signal circuit for the following conditions:

• | A short to voltage

• | An open

• | 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 6

6 | Test the low reference circuit for the following conditions:

• | A short to voltage

• | An open

• | High resistance

• | The CKP sensor circuits shorted together

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 | Test for an intermittent and for a poor connection at the PCM. 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 | Test for an intermittent and for a poor connection at the CKP sensor. 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 |

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

• | 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 13

Go to Step 10

10 | Inspect the CKP reluctor wheel for the following conditions:

• | Physical damage

• | Excessive end play or looseness

• | Improper installation

| Refer to Crankshaft and Bearing Cleaning and Inspection in Engine Mechanical.

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 complete the replacement? | -- | Go to Step 13 | --
12 | Replace the PCM. Refer to Powertrain Control Module Replacement Did you complete the replacement? | -- | Go to Step 13 | --
13 |

1. Turn OFF the ignition for 30 seconds.
2. Start the engine and operate the vehicle.
3. Observe the malfunction indicator lamp (MIL), vehicle performance, and driveability.

Does the vehicle operate normally, with no MIL illumination?

--

System OK

Go to Step 2