Pinpoint Test C: DTC P0579 Or DTC P0581

Cruise Control

Pinpoint Tests

Pinpoint Test C: DTC P0579 Or DTC P0581

Refer to Wiring Diagram Set 31, Cruise Control for schematic and connector information. Diagrams By Number

Normal Operation

The cruise control switches uses the PCM RUN/START voltage and the PCM ground. The cruise control functionality is controlled through the cruise control switches and is hard-wired to the PCM through a signal and return circuit.

There are 5 cruise control switches with each switch operating a specific function that uses different resistance values. The PCM sends out a reference voltage to the cruise control switches and monitors the voltage drop when a cruise control switch is pressed. The voltage drop varies depending upon the resistance of each switch, providing a specific indication to the PCM which switch is pressed, activating and controlling the cruise control system.

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

This pinpoint test is intended to diagnose the following:

- Wiring, terminals or connectors
- Clockspring
- Cruise control switches
- PCM

PINPOINT TEST C: DTC P0579 OR DTC P0581

NOTICE: 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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C1 CHECK THE CRUISE CONTROL SWITCH

- Ignition ON.
- Enter the following diagnostic mode on the scan tool: PCM DataLogger .
- Press each cruise control switch button while monitoring the SCCS PID (cruise control switch).

- Does the PID value agree with the switch position?

Yes
GO to C12.

No
If only one switch does not display the correct PID value, INSTALL a new cruise control switch. REFER to Cruise Control Switch Cruise Control Switch. CLEAR the DTCs. TEST the system for normal operation.

Otherwise, GO to C2.

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C2 CHECK THE CRUISE CONTROL SWITCH CIRCUITRY FOR A SHORT TO VOLTAGE

- Ignition OFF.
- Disconnect: PCM C175b .
- Ignition ON.
- Turn the parking lamps on.
- Measure the voltage between the PCM C175b-64, circuit VES10 (WH), harness side and ground; and between the PCM C175b-48, circuit RES08 (GN/BN), harness side and ground.

- Is any voltage present?

Yes
TURN the parking lamps off. GO to C3.

No
TURN the parking lamps off. GO to C6.

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C3 CHECK THE CRUISE CONTROL SWITCH CIRCUITRY FOR A SHORT TO VOLTAGE WITH THE CLOCKSPRING DISCONNECTED

- Ignition OFF.
- Disconnect: Clockspring C2274 .
- Ignition ON.
- Turn the parking lamps on.
- Measure the voltage between the PCM C175b-64, circuit VES10 (WH), harness side and ground; and between the PCM C175b-48, circuit RES08 (GN/BN), harness side and ground.

- Is any voltage present?

Yes
REPAIR the circuit in question. CLEAR the DTCs. TEST the system for normal operation.

No
TURN the parking lamps off. GO to C4.

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C4 CHECK THE CLOCKSPRING FOR A SHORT TO VOLTAGE

- Ignition OFF.
- Connect: Clockspring C2274 .
- Remove the driver air bag module. Refer to Supplemental Restraint System Driver Air Bag Module.
- Disconnect: Upper Clockspring .
- Connect the battery.
- Ignition ON.
- Turn the parking lamps on.
- Measure the voltage between the PCM C175b-64, circuit VES10 (WH), harness side and ground; and between the PCM C175b-48, circuit RES08 (GN/BN), harness side and ground.

- Is any voltage present?

Yes
INSTALL a new clockspring. INSTALL the driver air bag module. REFER to Supplemental Restraint System Driver Air Bag Module. CLEAR the DTCs. TEST the system for normal operation.

No
GO to C5.

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C5 CHECK THE STEERING WHEEL CRUISE CONTROL CIRCUITRY FOR A SHORT TO VOLTAGE

- Ignition OFF.
- Connect: Upper Clockspring .
- Disconnect: Cruise Control Switch .
- Ignition ON.
- Turn the parking lamps on.
- Measure the voltage between the PCM C175b-64, circuit VES10 (WH), harness side and ground; and between the PCM C175b-48, circuit RES08 (GN/BN), harness side and ground.

- Is any voltage present?

Yes
REPAIR the circuit in question in the steering wheel harness. CLEAR the DTCs. TEST the system for normal operation.

No
INSTALL a new cruise control switch. REFER to Cruise Control Switch Cruise Control Switch. INSTALL the driver air bag module. REFER to Supplemental Restraint System Driver Air Bag Module. CLEAR the DTCs. TEST the system for normal operation.

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C6 CHECK THE CRUISE CONTROL SWITCH CIRCUITRY FOR A SHORT TO GROUND

- Ignition OFF.
- Remove the driver air bag module. Refer to Supplemental Restraint System Driver Air Bag Module.
- Disconnect: Upper Clockspring .
- Measure the resistance between the PCM C175b-64, circuit VES10 (WH), harness side and ground; and between the PCM C175b-48, circuit RES08 (GN/BN), harness side and ground.

- Are the resistances greater than 10,000 ohms?

Yes
GO to C8.

No
GO to C7.

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C7 CHECK THE CLOCKSPRING FOR A SHORT TO GROUND

- Disconnect: Clockspring C2274 .
- Measure the resistance between the PCM C175b-64, circuit VES10 (WH), harness side and ground; and between the PCM C175b-48, circuit RES08 (GN/BN), harness side and ground.

- Are the resistances greater than 10,000 ohms?

Yes
INSTALL a new clockspring. INSTALL the driver air bag module. REFER to Supplemental Restraint System Driver Air Bag Module. CLEAR the DTCs. TEST the system for normal operation.

No
For uplevel cruise control switch, GO to C10.

For base cruise control switch, GO to C11.

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C8 CHECK THE CRUISE CONTROL SWITCH CIRCUITRY FOR AN OPEN

- Disconnect: Clockspring C2274 .
- Measure the resistance between the PCM C175b-64, circuit VES10 (WH), harness side and the clockspring C2274-15, circuit VES10 (WH), harness side.

- Measure the resistance between the PCM C175b-48, circuit RES08 (GN/BN), harness side and the clockspring C2274-14, circuit RES08 (GN/BN), harness side.

- Are the resistances less than 5 ohms?

Yes
GO to C9.

No
REPAIR the circuit in question. CLEAR the DTCs. TEST the system for normal operation.

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C9 CHECK THE CLOCKSPRING FOR AN OPEN

- Remove the driver air bag module. Refer to Supplemental Restraint System Driver Air Bag Module.
- Disconnect: Upper Clockspring .
- Measure the resistance between the clockspring C2274 pin 15, component side and the upper clockspring connector pin 8, component side.

- Measure the resistance between the clockspring C2274 pin 14, component side and the upper clockspring connector pin 9, component side.

- Are the resistances less than 5 ohms?

Yes
For uplevel cruise control switch, GO to C11.

For base cruise control switch, GO to C10.

No
INSTALL a new clockspring. INSTALL the driver air bag module. REFER to Supplemental Restraint System Driver Air Bag Module. CLEAR the DTCs. TEST the system for normal operation.

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C10 CHECK THE CIRCUITS TO THE STEERING WHEEL CONTROLS CIRCUITRY FOR AN OPEN OR SHORT TO GROUND (BASE)

NOTE: Circuit RES08 (GN/BN) does not need to be checked for a short to ground.

- Ignition OFF.
- Measure the resistance between the upper clockspring, harness side and the cruise control switch, harness side; and between the upper clockspring, harness side and ground as follows:

- Is the resistance less than 5 ohms between the clockspring and the steering wheel controls, and greater than 10,000 ohms between the upper clockspring and ground?

Yes
INSTALL a new cruise control switch. REFER to Cruise Control Switch Cruise Control Switch. INSTALL the driver air bag module. REFER to Supplemental Restraint System Driver Air Bag Module. CLEAR the DTCs. TEST the system for normal operation.

No
INSTALL a new steering wheel. REFER to Steering Column Removal and Replacement. CLEAR the DTCs. TEST the system for normal operation.

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C12 CHECK FOR CORRECT PCM OPERATION

- Disconnect all the PCM connectors.
- Check for:
- corrosion
- damaged pins
- pushed-out pins
- Connect all the PCM connectors and make sure they seat correctly.
- Operate the system and verify the concern is still present.
- Is the concern still present?

Yes
INSTALL a new PCM. REFER to Electronic Engine Controls Service and Repair. INSTALL the driver air bag module. REFER to Supplemental Restraint System Driver Air Bag Module. TEST the system for normal operation.

No
The system is operating correctly at this time. The concern may have been caused by a loose or corroded connector. INSTALL the driver air bag module. REFER to Supplemental Restraint System Driver Air Bag Module. CLEAR the DTCs. REPEAT the self-test.

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