Fix P0585: Mechanic’s solutions that WORKED

The P0585: Speed Control Switch 1/2 Correlation code signals a discrepancy between two cruise control switches, indicating that they are not functioning in tandem as they should. This can lead to erratic or non-functional cruise control operation. The code is likely caused by issues with the switches themselves, their wiring, or the cruise control module.

P0585 quick overview

Meaning	P0585: Speed Control Switch 1/2 Correlation
Is it serious?	This code is moderately serious as it can affect the functionality of the vehicle’s cruise control system but is unlikely to cause a breakdown.
Possible causes	– Faulty cruise control switches – Damaged or disconnected wiring to the switches – Corrosion or poor connections in the switch’s circuit – Issues with the cruise control module
How to diagnose?	Inspect Cruise Control Switches: Check the physical condition and functionality of the cruise control switches. Examine Wiring and Connectors: Look for any damaged, loose, or corroded connectors and wiring. Measure Voltage at Switch: Test the voltage at the cruise control switch during various button presses. Check Cruise Control Module: Inspect the cruise control module for faults or damages. Reset Cruise Control System: Perform a system reset and retest the functionality. Check for Continuity: Verify the continuity in the cruise control circuit.

How to fix P0585 – learn from mechanics

I looked into P0585 service cases at iatn.com website where in the private forums the mechanics seek advice from other mechanics. I looked up a bunch of cases to help you decide how to fix your issue and see what would a real mechanic do to solve it.

Case #1: Jeep

Vehicle Information: 2008 Jeep Grand Cherokee Laredo 4.7L

Issue + Repair History:

• Customer reported sudden unintended acceleration.
• Hit the brakes until the vehicle eventually stopped.
• Initial scans with a quick scanner showed no codes.
• Further diagnosis with a Launch scanner revealed two codes.

Computer Codes & Descriptions:

• PO585: Cruise Control Multi-Function Input A/B Correlation.
• P2299: Brake Pedal Position/Accelerator Pedal Position Incompatible.

Suggestions to Fix Issue:

• Check if the vehicle has a movable accelerator pedal that might be causing the issue.
• Be cautious of the possibility of accidentally pressing both pedals due to their close proximity.
• Check voltages for cruise control switch inputs in various switch positions.

Final Fix:

• The issue was caused by an incorrectly fitting aftermarket floor mat.
• The mat was short and creased, causing it to make the accelerator pedal stick.
• Reproducing the issue with the mat confirmed the cause.
• Removed or adjusted the floor mat to resolve the issue.

Case #2: Dodge

Vehicle Information: 2011 Dodge Ram 1500 5.7L

Issue + Repair History:

• MIL on and transmission in safe mode while driving.
• Issue occurred after driving 100km.
• DTCs returned 15 seconds after starting, even after deleting.
• Attempted disconnecting SPEED control switch from PCM, but DTC still present.

Computer Codes & Descriptions:

• P0750: Lr Solenoid Circuit.
• P0581: Speed Control Switch 1 Circuit High.
• P0585: Speed Control Switch 1/2 Correlation.
• P0882: TCM Power Input Low.
• P1593: Speed Control Switch 1 Stuck.

Suggestions to Fix Issue:

• Test speed control switches and verify good ground.
• Start with P0882, as it could be caused by the TCM relay in the TIPM or an internal fused circuit.
• Check for full 12-volt power from the trans control relay to the transmission connector.
• Check all power feeds in the intelligent power module for a blown fuse or a non-working relay.
• Consider the possibility of a faulty cruise control switch.
• Focus on P0882, as it might be the root cause of the issues.

Final Fix:

• The problem was the PCM.
• Replaced the PCM, then flashed and learned the VIN.
• All problems resolved after PCM replacement.

Case #3: Dodge

Vehicle Information: 2003 Dodge Ram 1500 SLT 5.7L

Issue + Repair History:

• Truck runs rough, barely idles, and was towed in.
• Difficult to keep running.
• Ticking sound coming from one of the cylinders.

Computer Codes & Descriptions:

• P2106: ETC System – Forced Limited Power.
• P2108: ETC Module Performance.
• PO585: Speed Control Switch 1/2 Correlation.
• PO300: Multiple Misfire.

Suggestions to Fix Issue:

• Check for broken exhaust valve springs, a common problem with these engines.
• Test foot feed and throttle body TPS for glitches.
• Disconnect EGR valve, reset PCM, and restart the truck.
• Perform software update and throttle sensor recalibration as per TSB 18/013/03.
• Conduct a compression test, preferably a relative compression test.

Final Fix:

• Found a broken exhaust valve spring on cylinder 1.
• Replaced all 8 springs with Mopar parts.
• Vehicle runs fine after the replacement.

Case #4: Honda

Vehicle Information: 2009 Honda Accord EX 2.4L

Issue + Repair History:

• Cruise control not functioning properly.
• The cruise control would not set or would randomly disengage.
• Code P0585 indicated a problem with the switch correlation.

Computer Codes & Descriptions:

• P0585: Speed Control Switch 1/2 Correlation.

Suggestions to Fix Issue:

• Check the functionality of the individual cruise control buttons.
• Inspect for loose or corroded connectors at the cruise control switch.
• Verify the continuity and resistance in the cruise control switch circuit.
• Reset the cruise control system and retest.

Final Fix:

• Found corrosion in the connectors of the cruise control switch.
• Cleaned the connectors and secured them properly.
• The cruise control system functioned correctly without further issues after this fix.

Case #5: Ford

Vehicle Information: 2012 Ford F-150 XLT 3.5L

Issue + Repair History:

• Erratic cruise control function.
• Vehicle’s cruise control was intermittently engaging and disengaging.
• Code P0585 for cruise control switch correlation was set.

Computer Codes & Descriptions:

• P0585: Speed Control Switch 1/2 Correlation.

Suggestions to Fix Issue:

• Inspect the cruise control switches and their wiring for damage or wear.
• Test the voltage changes at the cruise control switch to ensure proper function.
• Clean and secure the connections at the cruise control module.
• Consider replacing the cruise control switches if they appear worn or defective.

Final Fix:

• Replaced the cruise control switches.
• After replacement, the cruise control functioned normally without intermittent issues.

Advice	Brief Description of Diagnostic Step
Inspect Cruise Control Switches	Check the switches for physical damage, wear, or improper functioning.
Check Wiring and Connectors	Examine wiring and connectors for damage, corrosion, or loose connections.
Test Voltage Changes at Switch	Measure voltage at the cruise control switch during different commands.
Clean and Secure Connections	Clean any corrosion and ensure connectors are properly secured.
Consider Switch Replacement	Replace cruise control switches if they appear defective or worn out.
Reset Cruise Control System	Perform a system reset and retest to see if the issue is resolved.
Verify Continuity and Resistance in Circuit	Check for proper electrical flow and resistance in the switch circuit.