I have a 06 3500 5.9 automatic 4x4 Laramine QC. I keep geting the code P0581. I clear it and it keeps coming back. My cruise works sometimes and othertimes it doesnt. The cruise light on the dash comes on when it works and doesnt come on when it doesnt work. When it does work I will be going down the road and all of a sudden the cruise just kicks out and the cruise light shuts off. Does anyone out there know whats happening? I have brought it to my mechanic numerous times and he clears the code and he cant seem to find whats causing it. When have no clue thats why I am coming to you.

 

Here's what the manual says about it. I do not have any personal experience with this...

Symptom:
P0581-HIGH VOLTAGE DETECTED AT THE SPEED CONTROL SWITCH
When Monitored and Set Condition:
P0581-HIGH VOLTAGE DETECTED AT THE SPEED CONTROL SWITCH
When Monitored: Key on or Engine running.
Set Condition: Speed Control MUX switch above 11.5 volts for 5 seconds.
POSSIBLE CAUSES
S/C WIRING HARNESS OBSERVABLE PROBLEM
CLOCKSPRING SIGNAL/GROUND CIRCUIT OPEN
SPEED CONTROL ON/OFF SWITCH
S/C SWITCH SIGNAL CKT SHORTED TO VOLTAGE
S/C SWITCH SIGNAL CIRCUIT OPEN ECM TO CLOCK SPRING
S/C SWITCH SIGNAL CIRCUIT OPEN CLOCKSPRING TO S/C SWITCH
S/C SWITCH GROUND CIRCUIT OPEN CLOCKSPRING TO S/C SWITCH
S/C SWITCH GROUND CIRCUIT OPEN ECM TO CLOCKSPRING
ECM
TEST ACTION APPLICABILITY
1 Turn the ignition on.
With the DRBIIIt in Inputs/Outputs, read the Speed Control inputs state in ECM.
While monitoring the DRBIIIt, push the Speed Control On/Off Switch several times, then leave it on.
Did the DRBIIIt show Speed Control Switch off and on?
Yes Go To 2
No Test Complete.
2 Turn the ignition off.
Using the Schematics as a guide, inspect the Wiring and Connectors.
Were any problems found?

Yes Repair as necessary.
No Go To 3
3 Disconnect the upper and lower 6-way clockspring harness connectors.
Note: Check connectors - Clean/repair as necessary.
Measure the resistance of the sensor ground circuit between the upper and lower 6-way clockspring harness connectors.
Measure the resistance of the speed control switch signal circuit between the upper and lower 6-way clockspring harness connectors.
Was the resistance above 5.0 ohms for either circuit?

Yes Replace the clockspring.

No Go To 4
4 Disconnect the Speed Control On/Off Switch 2-way harness connector only.
Note: Check connectors - Clean/repair as necessary.
Measure the resistance across the S/C On/Off Switch.
Is the resistance between 20.3K and 20.7K ohms?
Yes Go To 5
No Replace the On/Off Switch.
5 Turn the ignition on.
Measure the voltage of the S/C Switch Signal Circuit at the On/Off Switch 2-way connector.
Is the voltage above 6.0 volts?

Yes Repair the Speed Control Switch Signal Circuit for a short to voltage.
No Go To 6
6 Turn the ignition off.
Disconnect the ECM harness connector.
Note: Check connectors - Clean/repair as necessary.
Measure the resistance of the S/C Switch Signal Circuit between the ECM connector and the Clockspring Connector.
Is the resistance below 5.0 ohms?
Yes Go To 7
No Repair open Speed Control Switch Signal Circuit ECM to Clockspring.
7 Measure the resistance of the S/C Switch Signal Circuit from the clockspring harness connector to the On/Off switch harness connector.
Is the resistance below 5.0 ohms?
Yes Go To 8
No Repair the open Speed Control Switch Signal Circuit Clockspring to S/C switch.
8 Measure the resistance of the S/C Switch Sensor Ground Circuit between the On/Off Switch 2-way harness connector to the clockspring harness connector.
Is the resistance below 5.0 ohms?
All
Yes ! Go To 9
No ! Repair open ground circuit from clockspring to S/C switch.
9 Measure the resistance of the S/C Switch Sensor Ground Circuit between the ECM harness connector to the clockspring harness connector.
Is the resistance below 5.0 ohms?
Yes Replace and program the ECM in accordance with the Service
Information.
No Repair open ground circuit from ECM to clockspring.