Pinpoint Test 3: The Speed Control Switches Do Not Operate Correctly

PINPOINT TEST 3: THE SPEED CONTROL SWITCHES DO NOT OPERATE CORRECTLY

NOTE:Tapping the brake pedal deactivates the speed control. It is necessary to apply the brakes in order to slow the vehicle down.

Normal Operation

Voltage is sent from the PCM to the speed control switches through circuit (W). When a switch is pressed, the voltage is routed through a specific resistor value for each function. The PCM grounds the reference voltage through circuit (G/BR). The PCM uses this reference voltage to determine which speed control input function has been selected.

- DTC P0579 (Cruise Control Multifunction Input A Circuit Range/Performance) - sets when the speed control switch circuits are open, shorted to voltage or ground.
- DTC P0581 (Cruise Control Multi-Function Input A Circuit High) - sets when the speed control switch circuits are open or shorted to voltage.

Possible Causes
- Wiring, terminals or connectors
- Clockspring
- Speed control switches
- PCM

Diagnostic Procedure

CAUTION:Use the correct probe adapter(s) when making measurements. Failure to use the correct probe adapter(s) may damage the connector.

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