P0579-SPEED CONTROL SWITCH 1 PERFORMANCE

For a complete wiring diagram Refer to Section 8W.

When Monitored:
With the ignition key on.
Set Condition:
Cruise switch voltage output is not out of range but it does not equal any of the values for any of the button positions. One trip fault.

Possible Causes

(V371) S/C SWITCH NO.1 SIGNAL CIRCUIT SHORTED TO BATTERY VOLTAGE

(V71) S/C SWITCH NO.1 SIGNAL CIRCUIT SHORTED TO BATTERY VOLTAGE

(V371) S/C SWITCH NO.1 SIGNAL CIRCUIT OPEN

(V71) S/C SWITCH NO.1 SIGNAL CIRCUIT OPEN

(V397) SWITCH RETURN CIRCUIT OPEN

(V937) SWITCH RETURN CIRCUIT OPEN

(V371) S/C SWITCH NO.1 SIGNAL CIRCUIT SHORTED TO GROUND

(V71) S/C SWITCH NO.1 SIGNAL CIRCUIT SHORTED TO GROUND

(V371) S/C SWITCH NO.1 SIGNAL CIRCUIT SHORTED TO THE (V397) SWITCH RETURN CIRCUIT

(V71) S/C SWITCH NO.1 SIGNAL CIRCUIT SHORTED TO THE (V937) SWITCH RETURN CIRCUIT

STEERING COLUMN CONTROL MODULE

SPEED CONTROL SWITCH

PCM

Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. (Refer to 9 - ENGINE - DIAGNOSIS AND TESTING).

Diagnostic Test

1.SPEED CONTROL SWITCH STATUS

Does each switch function change status when pressing and then depressing each switch?

Yes

Refer to the INTERMITTENT CONDITION Diagnostic Procedure.
Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)

Go To 2

2.SPEED CONTROL SWITCH

Does the function on the Speed Control Switches have the correct resistance value?

Yes

Go To 3

Replace the Speed Control Switch that had the incorrect resistance value.
Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)

3.(V371) S/C SWITCH NO.1 SIGNAL CIRCUIT SHORTED TO BATTERY VOLTAGE

Is the voltage above 0 volts?

Yes

Repair the short to battery voltage in the (V371) S/C Switch No.1 Signal circuit.
Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)

Go To 4

4.(V71) S/C SWITCH NO.1 SIGNAL CIRCUIT SHORTED TO BATTERY VOLTAGE

Is the voltage above 0 volts?

Yes

Repair the short to battery voltage in the (V71) S/C Switch No.1 Signal circuit.
Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)

Go To 5

5.STEERING COLUMN CONTROL MODULE

Is the resistance above 5.0 ohms for either reading?

Yes

Replace the Steering Column Control Module per Service Information.
Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)

Go To 6

6.(V371) S/C SWITCH NO.1 SIGNAL CIRCUIT OPEN

NOTE: The measurement must be taken from both Speed Control Switch harness connectors.

Is the resistance below 5.0 ohms for each measurement?

Yes

Go To 7

Repair the open in the (V371) S/C Switch No.1 Signal circuit.
Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)

7.(V71) S/C SWITCH NO.1 SIGNAL CIRCUIT OPEN

CAUTION: Do not probe the PCM harness connectors. Probing the PCM harness connectors will damage the PCM terminals resulting in poor terminal to pin connection. Install Miller Special Tool #8815 to perform diagnosis.

Is the resistance below 5.0 ohms for both measurements?

Yes

Go To 8

Repair the open in the (V71) S/C Switch No.1 Signal circuit.
Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)

8.(V397) SWITCH RETURN CIRCUIT OPEN

NOTE: The measurement must be taken from both Speed Control Switch harness connectors.

Is the resistance below 5.0 ohms for each measurement?

Yes

Go To 9

Repair the open in the (V397) Switch Return circuit.
Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)

9.(V937) SWITCH RETURN CIRCUIT OPEN

Is the resistance below 5.0 ohms for both measurements?

Yes

Go To 10

Repair the open in the (V937) Switch Return circuit.
Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)

10.(V71) S/C NO.1 SWITCH SIGNAL CIRCUIT SHORTED TO GROUND

Is the resistance below 100 ohms?

Yes

Repair the short to ground in the (V71) S/C Switch No.1 Signal circuit.
Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)

Go To 11

11.(V371) S/C NO.1 SWITCH SIGNAL CIRCUIT SHORTED TO GROUND

Is the resistance below 100 ohms?

Yes

Repair the short to ground in the (V371) S/C Switch No.1 Signal circuit.
Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)

Go To 12

12.(V371) S/C SWITCH NO.1 SIGNAL CIRCUIT SHORTED TO THE (V397) S/C SWITCH RETURN CIRCUIT

Is the resistance below 5.0 ohms?

Yes

Repair the short between the (V371) S/C Switch No.1 Signal circuit and the (V397) Switch Return circuit.
Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)

Go To 13

13.(V71) S/C SWITCH NO.1 SIGNAL CIRCUIT SHORTED TO THE (V937) S/C SWITCH RETURN CIRCUIT

Is the resistance below 5.0 ohms?

Yes

Repair the short between the (V71) S/C Switch No.1 Signal circuit and the (V937) Switch Return circuit.
Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)

Go To 14

14.SPEED CONTROL SWITCH VOLTAGE VALUES

SWITCH POSITION	SWITCH No.1 VOLTAGE VALUE	SWITCH No.2 VOLTAGE VALUE
NO SWITCHES PRESSED	4.31 to 4.78 volts	4.31 to 4.78 volts
ON/OFF PRESSED	0.59 to 1.13 volts	3.53 to 3.92 volts
RES/ACCEL PRESSED	3.88 to 4.17 volts	2.04 to 2.47 volts
SET PRESSED	3.16 to 3.56 volts	1.17 to 1.56 volts
COAST PRESSED	2.57 to 2.94 volts	0.77 to 1.09 volts
CANCEL PRESSED	1.59 to 1.99 volts	2.84 to 3.25 volts

Are the voltage readings out of the listed specification and is there less than a 0.2 of a volt difference between the voltmeter switch values and the scan tool switch value?

Yes

Replace the Speed Control Switch.
Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)

Go To 15

15.PCM

NOTE: Before continuing, check the PCM harness connector terminals for corrosion, damage, or terminal push out. Repair as necessary.

Were there any problems found?

Yes

Repair as necessary.
Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)

Replace and program the Powertrain Control Module per Service Information.
Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)