C1917

What Does Code C1917 Mean?

DTC C1917 signifies an Electronic Variable Orifice (EVO) Steering Out-of-Range Fault. This code indicates that the Powertrain Control Module (PCM), or more commonly, a dedicated Steering Control Module (SCM), has detected an electrical or functional discrepancy within the EVO power steering system. The EVO system is a sophisticated, speed-sensitive power steering mechanism designed to dynamically adjust the amount of hydraulic assistance provided to the driver based on vehicle speed. At lower speeds, the system maximizes assist for effortless maneuvering and parking, while at higher speeds, it reduces assist to enhance road feel, stability, and control.

The control module monitors the operational parameters of the EVO solenoid valve, which typically regulates hydraulic fluid flow or pressure within the power steering pump or rack. An “out-of-range” fault means that the electrical signal (e.g., current draw, voltage feedback) or the hydraulic response from the EVO actuator is outside the manufacturer’s specified minimum or maximum thresholds for a given operating condition (such as vehicle speed, steering angle, or engine RPM). This could be due to an electrical malfunction within the solenoid itself (e.g., open circuit, short circuit, excessive resistance), a problem with the control circuit wiring, or an internal fault within the solenoid valve causing it to stick or fail to respond correctly. The primary subsystem affected is the vehicle’s power steering, leading to inconsistent or incorrect steering effort.

Common Symptoms

• Inconsistent Steering Effort: The most prevalent symptom, where steering may feel excessively light at high speeds, unusually heavy at low speeds, or experience sudden changes in steering effort during operation.
• Illuminated Warning Lights: Depending on the vehicle manufacturer, a Check Engine Light (MIL), Service Power Steering Light, or another specific chassis system warning light may illuminate on the instrument cluster.
• Reduced or No Power Steering Assist: In severe cases, the EVO system may default to a fail-safe mode, potentially resulting in significantly reduced or entirely absent power steering assistance, making the vehicle difficult to steer.
• Abnormal Steering Feel: The steering wheel might feel loose, vague, or exhibit excessive play, particularly when driving at varying speeds.

What Causes the Code C1917?

• Faulty EVO Solenoid/Actuator: The most common cause, where the internal coil of the EVO solenoid valve is open, shorted, or has excessive resistance. The valve mechanism itself may also be mechanically stuck, clogged, or binding.
• Wiring Harness or Connector Issues: Damaged, corroded, or loose wiring within the EVO control circuit, or faulty electrical connectors leading to the EVO solenoid or its respective control module (PCM/SCM). This includes opens, shorts to ground, or shorts to power.
• Failed Steering Control Module (SCM) or Powertrain Control Module (PCM): An internal fault within the module responsible for controlling the EVO system can cause incorrect signal output or misinterpretation of feedback, triggering the code.
• Incorrect or Erratic Vehicle Speed Sensor (VSS) Input: If the EVO system relies on an accurate VSS signal to determine the appropriate assist level, an erratic or incorrect VSS reading could cause the control module to detect an “out-of-range” condition in the EVO system’s response.
• Power Steering Pump Malfunction: While less direct, a severely underperforming or overperforming power steering pump could, in some systems that monitor hydraulic pressure feedback, lead to the EVO valve being unable to achieve the desired pressure range, thus triggering the fault.

How to Diagnose and Troubleshoot

A systematic diagnostic approach is crucial for C1917:

1. Initial Scan and Data Analysis:
   • Connect an OBD-II scan tool and retrieve all stored Diagnostic Trouble Codes (DTCs), including pending and historical codes. Note any other related codes, especially those pertaining to the Vehicle Speed Sensor (VSS), Steering Angle Sensor (SAS), or communication with the Steering Control Module (SCM).
   • Review freeze frame data associated with C1917 to understand the engine speed, vehicle speed, and other parameters when the fault was set.
   • Monitor live data for the VSS, SAS (if applicable), and any available EVO system parameters (e.g., solenoid duty cycle, commanded assist level, actual assist level) while replicating driving conditions where the symptom occurs. Verify VSS readings are accurate and stable.
2. Visual Inspection:
   • Carefully inspect the EVO solenoid valve and its surrounding wiring harness and electrical connectors. Look for signs of physical damage, corrosion, chafing, melted insulation, or loose connections. Pay close attention to areas where the harness passes through grommets or near moving parts.
   • Verify the power steering fluid level is correct and the fluid condition is clean. While C1917 is primarily an electrical fault, proper fluid levels and quality are essential for overall system operation.
3. Electrical Testing of EVO Solenoid (using a Digital Multimeter – DMM):
   • Locate the EVO solenoid valve (typically mounted on the power steering pump or rack-and-pinion assembly).
   • Disconnect the electrical connector from the EVO solenoid.
   • Using a DMM set to Ohms, measure the internal resistance across the two terminals of the EVO solenoid itself. Compare this reading to the manufacturer’s specifications (typically a low resistance value, e.g., 2-10 Ohms). An open circuit (OL or infinite resistance) or a dead short (near 0 Ohms) indicates a faulty solenoid requiring replacement.
   • With the ignition ON (engine OFF), measure the voltage at the EVO solenoid connector on the vehicle’s harness side. One terminal should typically have battery voltage or a reference voltage, and the other should be a control signal from the SCM/PCM, which may fluctuate or be a pulsed signal depending on the system design. Confirm power and ground are present at the connector.
4. Wiring Harness Integrity Check:
   • Perform continuity tests on the EVO solenoid control circuit wiring between the solenoid connector and the SCM/PCM connector. Disconnect both ends of the circuit before testing to prevent damage to control modules.
   • Check for shorts to ground and shorts to power in the EVO control wires. An unintended short can cause an out-of-range reading.
   • Verify the integrity of the ground circuit for the SCM/PCM and the EVO solenoid.
5. Control Module Diagnostics:
   • If the EVO solenoid and all associated wiring test good, and input sensors like VSS are verified to be accurate, the fault may lie within the Steering Control Module (SCM) or PCM.
   • If available, perform a self-test or communication test on the SCM using an advanced scan tool.

Recommended Repairs and Solutions

Based on the diagnostic findings, the following repairs are typically recommended:

• Replace the EVO Solenoid/Actuator: If electrical resistance testing confirms an internal fault (open, short, or out-of-spec resistance) within the EVO solenoid, replacement of the solenoid valve is the most common repair. In some vehicles, the solenoid may be an integral part of the power steering pump or steering rack and may require replacement of a larger assembly.
• Repair or Replace Damaged Wiring and Connectors: If the visual inspection or electrical continuity tests reveal damaged wiring, corroded terminals, or loose connectors in the EVO circuit, these components must be repaired or replaced using OEM-approved methods (e.g., soldering and heat shrinking for wire repairs, replacing entire connector pigtails if terminals are extensively damaged). Ensure proper weatherproofing.
• Replace the Steering Control Module (SCM) or PCM: If all external components and wiring test correctly, and input signals are verified, the SCM or PCM may be faulty. Be aware that replacing a control module often requires specific programming or calibration procedures by a dealership or a specialist with factory diagnostic equipment to ensure proper communication and function within the vehicle’s network.
• Address Faulty Input Sensors: If diagnostics identify an erratic or faulty Vehicle Speed Sensor (VSS) or Steering Angle Sensor (SAS) as the root cause (due to the EVO system misinterpreting conditions), replace the respective sensor and clear the codes.
• Verify Power Steering System Integrity: While fixing electrical faults, it is good practice to ensure the power steering system has the correct fluid level and that the fluid is clean and free of contamination. Perform a fluid flush if necessary, and inspect for any leaks or pump noise that might indicate a secondary issue.