P0585 — Cruise Control Multi-Function Input « A »/ »B » Correlation
Introduction:
The diagnostic trouble code P0585 indicates a problem related to the cruise control system, specifically a malfunction in the multi-function input signals labeled as « A » and « B ». When this code appears, it suggests a discrepancy or correlation issue between these two input signals, which are essential for proper cruise control operation.
Please note that labels and terminology may vary between different vehicle manufacturers. This means that some cars may use different codes or wording for similar issues.
Fast Facts:
- System affected: Cruise Control System
- Severity: Moderate — requires diagnosis and correction
- Main symptoms: Cruise control may disengage, warning lights appear, or no issues
- Driveability: Limited — primarily affects cruise control operation, vehicle can typically be driven normally
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Manufacturer variations for trouble code P0585
Different vehicle manufacturers may assign varying labels or code designations to issues related to cruise control input correlation problems. Since OBD-II codes are standardized but can have manufacturer-specific extensions, it’s important to verify the exact code meanings in the specific OEM documentation.
Known label variations include:
- Ford: CWT (Cruise Control Multi-Function Signal « A »/ »B » Correlation)
- BMW: 4F01
- Volkswagen/Audi: 18263 (or similar variation)
- Toyota: C1244
- Hyundai/Kia: P0585 (or related code)
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What does trouble code P0585 mean?
In simple language, P0585 points to a communication or signal discrepancy within the cruise control system. The vehicle’s Engine Control Unit (ECU) constantly monitors two inputs—labelled « A » and « B »—which are designed to work in harmony to control cruise functions. When these signals do not match or do not follow expected correlation patterns, the ECU triggers this code.
More specifically:
– **What the ECU monitors:** The signals from multiple sensors or switches involved in cruise control activation, such as the cruise stalk (or switch) inputs and other related sensors.
– **What triggers the code:** Mismatched or inconsistent signals received from the cruise control input lines, often caused by wiring issues, faulty switches, or control modules.
– **Typical context:** The code might appear after attempting to activate cruise control, during normal driving, or following repairs involving electrical components of the cruise control system.
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Severity and risks of trouble code P0585
This code generally points to a moderate level of concern. It primarily affects the functioning of the cruise control system, meaning the driver may not be able to use cruise control functions properly. Importantly, the core engine and transmission operations are usually unaffected.
**Potential risks include:**
– Reduced convenience when highway driving or long trips
– Possible unintended disengagement of cruise control
– In rare cases, if the underlying cause involves wiring or sensor faults, electrical issues could impact other systems
**Can the vehicle be driven?**
Yes — the vehicle can generally be driven normally, but the cruise control feature might be disabled or intermittently functioning. For safety and comfort, repair should be scheduled as soon as possible.
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Symptoms of trouble code P0585
The presence of P0585 may not always produce obvious symptoms, but some common signs include:
– The cruise control system disengaging unexpectedly
– Warning lights related to cruise control or ABS illuminating on the dashboard
– Inability to activate or maintain cruise control speed
– Intermittent or no response from cruise switch inputs
– Diagnostic trouble codes stored alongside other cruise control or electrical issues
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Most likely causes of trouble code P0585
This code’s origins are often electrical or sensor-related. Addressing the root cause requires considering common issues affecting cruise control input signals:
1. **Damaged or disconnected wiring or connectors:** Wiring harnesses linked to the cruise control switches or modules may be corroded, damaged, or poorly connected.
2. **Faulty cruise control switch or stalk:** The switch that the driver uses to engage and control cruise may have failed.
3. **Defective cruise control module:** The control unit itself might have experienced a fault or internal failure.
4. **Electrical interference or grounding issues:** Poor grounding or electromagnetic interference can disrupt signal integrity.
5. **Problems within the vehicle’s CAN bus network:** Since cruise control signals often communicate via the vehicle’s control area network, network faults can cause issues.
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How to diagnose trouble code P0585
When diagnosing P0585, always approach with a clear, methodical process, prioritising safety and avoiding unnecessary parts replacement. Typical diagnostic steps include:
1. **Visual inspection:** Check all relevant wiring, connectors, and switches connected to the cruise control system for damage, corrosion, or loose connections.
2. **Review live data:** Use a diagnostic scanner to monitor the cruise control input signals and verify their consistency when switching cruise functions on and off.
3. **Test switches and wiring:** Use a multimeter or test light to confirm proper voltage, continuity, and signal flow in the input circuits.
4. **Check the cruise control module:** If accessible, inspect or test the module or control unit for faults or internal failures, or consider replacing if necessary.
5. **Scan for related codes:** Look for additional fault codes that could point to wiring issues, sensor problems, or other control system malfunctions.
6. **Perform a relay or fuse check:** Confirm that cruise control relays and fuses are functioning correctly and are not blown or damaged.
7. **Reset and re-test:** Clear the fault and see if it reappears during typical driving conditions.
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Possible repairs for trouble code P0585
Repairs for P0585 usually target the identified root causes. Some potential solutions include:
– **Cleaning or replacing wiring and connectors:** Basic repair typically performed by the DIY enthusiast or professional mechanic. Ensures proper electrical connections.
– **Replacing the faulty cruise control switch/stalk:** Often needed if switch inputs are detected as malfunctioning. Requires some disassembly around the steering column or dashboard.
– **Repairing or replacing the cruise control control module:** When internal faults are identified, this component must be replaced. Professional repair recommended due to complexity.
– **Addressing grounding issues:** Ensuring that all grounds related to the cruise control system are secure and free of corrosion.
– **Fixing wiring harnesses:** Replacing damaged or corroded wiring or connectors.
– **Software update or reprogramming:** Sometimes, manufacturer updates address known issues with cruise control modules. This action should be performed by an authorized dealer or qualified technician.
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Vehicles commonly associated with trouble code P0585 in Europe
While this code can appear across various brands, certain vehicle groups are more frequently involved. In Europe, typical affected makes include:
– **Volkswagen Group:** Audi, Volkswagen, Škoda, SEAT (mainly models with digital cruise control systems)
– **BMW:** Especially models with digital cruise control modules
– **Ford:** Various models, notably those with integrated cruise control modules
– **Peugeot and Citroën:** Particularly newer models with integrated control systems
– **Mercedes-Benz:** When electrical systems related to cruise control are involved
Note: The occurrence of P0585 can vary depending on year, model, and specific system configurations.
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Frequent mistakes with trouble code P0585
In diagnosing and repairing P0585, common errors may include:
– Replacing parts without proper testing: Jumping straight to module replacement without verifying wiring, switches, or signals can lead to unnecessary costs.
– Overlooking simple wiring issues: Corrosion, loose connections, or damaged wiring harnesses are frequent culprits but are sometimes overlooked.
– Ignoring related codes: Not checking for other fault codes may cause missed diagnosis of underlying problems.
– Misinterpreting live data: Failing to understand signal patterns or misreading sensor signals can lead to incorrect repairs.
– Failure to perform a proper reset after repairs: Not clearing faults or testing updates can result in repeated faults.
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FAQ — trouble code P0585
Q: Can this code disappear on its own?
A: It is unlikely for P0585 to resolve spontaneously. Usually, it indicates an underlying electrical or sensor issue that needs attention.
Q: Can I keep driving?
A: Yes, but the cruise control system may be disabled or intermittently unreliable. It is safe to drive but recommended to address the fault to restore full functionality.
Q: Why does the code return after clearing?
A: The root cause, such as wiring faults or a defective switch, often persists or reoccurs. Proper diagnosis and repair are necessary to prevent recurrence.
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