For 1990-2009 cars

### Circuit Description

The cruise control switch is an input to the engine control module (ECM). The ECM monitors the cruise control set/coast and resume/accelerate switch signal circuit in order to detect when a cruise control function has been requested. The ECM detects a specific voltage signal on the cruise control set/coast and resume/accelerate switch signal circuit when a cruise control function switch is activated, with each switch having a different predetermined voltage value.

### DTC Descriptor

This diagnostic procedure supports the following DTC:

DTC P0564 Cruise Control Multi-function Switch Circuit

### Conditions for Setting the DTC

• | The engine is running.

• | Ignition voltage is greater than 7.9956 volts.

### Action Taken When the DTC Sets

• | The malfunction indicator lamp (MIL) will not illuminate.

• | The ECM will record operating conditions at the time the diagnostic fail. This information will be stored in the Freeze Frame and Failure Records buffers.

• | A history DTC is stored.

### Conditions for Clearing the MIL/DTC

• | A history DTC will clear after 40 warm-up cycles without a fault.

• | DTCs can be cleared by using the scan tool.

### Diagnostic Aids

For an intermittent condition, refer to Testing for Intermittent Conditions and Poor Connections .

Step | Action | Values | Yes | No
--- | --- | --- | --- | ---
1 | Did you perform the Diagnostic System Check - Vehicle? | -- | Go to Step 2 | Go to Diagnostic System Check - Vehicle
2 |

1. Turn the ignition OFF.
2. Disconnect the cruise control switch connector.
3. Turn ON the ignition, with the engine OFF.
4. With a DMM, measure the voltage of the ignition 1 voltage circuit.

Does the voltage measure at the specified value?

B+

Go to Step 3

Go to Step 7

3 |

1. Turn OFF the ignition.
2. With a DMM, measure the resistance of the cruise control switch between the connector terminal 1 and the terminal 4 respectively, while pressing the cruise control switch ON and OFF.

Does the cruise control function switch resistance values measure between the specified values?

Switch On = ∞ ohms

Switch Off = 0 ohms

Go to Step 4

Go to Step 5

4 | Test the cruise control set/coast and resume/accelerate switch signal circuit for a high resistance, a short to voltage, or a short to ground between the cruise control switch and the engine control module (ECM). Did you find and correct the condition? | -- | Go to Step 10 | Go to Step 6
5 | Inspect for poor connections at the connector of the multifunction switch. Refer to Testing for Intermittent Conditions and Poor Connections . Did you find and correct the condition? | -- | Go to Step 10 | Go to Step 8
6 | Inspect for poor connections at the harness connector of the ECM. Refer to Testing for Intermittent Conditions and Poor Connections . Did you find and correct the condition? | -- | Go to Step 10 | Go to Step 9
7 | Repair the high resistance in the ignition 1 voltage circuit. Did you complete the repair? | -- | Go to Step 10 | --
8 | Once the replacement is complete verify the repair. Did you complete the repair? | -- | Go to Step 10 | --
9 | Replace the ECM. Refer to:

• | Engine Control Module Replacement for the 1.2L engine

• | Engine Control Module Replacement for the 1.4L DOHC engine

• | Engine Control Module Replacement for the 1.4L SOHC engine

• | Engine Control Module Replacement for the 1.5L engine

• | Engine Control Module Replacement for the 1.6L (L91) engine

Did you complete the replacement?

--

Go to Step 2

--

10 |

1. Use the scan tool in order to clear the DTCs.
2. Operate the vehicle within the Conditions for Setting the DTC.

Does the DTC reset?

--

Go to Step 2

System OK