C1923

What Does Code C1923 Mean?

DTC C1923 signifies an electrical fault within the circuit for the Variable Assist Power Steering (VAPS) Solenoid Actuator, specifically indicating a “Short To Battery” condition on its output circuit. The VAPS system, often controlled by the Power Steering Control Module (PSCM) or integrated within the Powertrain Control Module (PCM), is designed to modulate power steering assist based on vehicle speed and driving conditions. At lower speeds, it increases hydraulic assistance for easier maneuverability, while at higher speeds, it reduces assistance for better road feel and stability.

The VAPS solenoid actuator typically receives a pulsed-width modulated (PWM) signal or a varied voltage signal from the control module to adjust the hydraulic pressure or flow within the power steering system. When code C1923 is set, the control module detects that the voltage on the VAPS solenoid actuator output circuit is persistently at or near battery voltage (B+), even when it should be lower, off, or modulated to a different value. This indicates an unintended connection to a constant power source, preventing the control module from accurately controlling the solenoid’s operation. The affected subsystem is the vehicle’s power steering system, compromising its variable assist functionality and potentially leading to a fixed, often reduced, level of steering assist.

Common Symptoms

• Inconsistent or Heavy Steering Effort: The most prevalent symptom, as the VAPS system cannot correctly adjust assistance. Steering may feel heavier than normal, especially at low speeds, or inconsistently weighted.
• Reduced Power Steering Assist: The system may revert to a default, lower assist setting, making turning more strenuous.
• Illuminated Warning Lights: The Malfunction Indicator Lamp (MIL) or a dedicated Power Steering Warning Light on the instrument cluster may illuminate.
• Audible Noise from Power Steering Pump: In some cases, the power steering pump may exhibit unusual noises due to incorrect pressure regulation.

What Causes the Code C1923?

• Damaged Wiring Harness: The most common cause is a chafed or damaged wire in the VAPS solenoid actuator circuit, causing it to short directly to an adjacent power wire (B+) or to another constantly powered circuit within the vehicle’s harness.
• Faulty VAPS Solenoid Actuator: An internal short circuit within the solenoid itself can cause the output circuit to draw excessive current or to be directly connected to its internal power supply, mimicking a short to battery.
• Corroded or Damaged Connectors: Corrosion or physical damage to the VAPS solenoid actuator connector, or the corresponding pins at the PSCM/PCM connector, can create a conductive path to battery voltage.
• Faulty Power Steering Control Module (PSCM) or PCM: Although less common, an internal fault within the control module’s driver circuit for the VAPS solenoid could cause it to continuously output battery voltage, independent of its command.

How to Diagnose and Troubleshoot

A systematic approach is crucial for diagnosing C1923:

1. Initial Inspection and Scan Tool Check:
   • Begin with a thorough visual inspection of the VAPS solenoid actuator, its electrical connector, and the entire wiring harness leading to it from the control module. Look for obvious signs of chafing, cuts, pinch points, corrosion, or heat damage.
   • Connect an OBD-II scan tool. Check for any other related or pending diagnostic trouble codes (DTCs) that might offer additional clues. Note the freeze frame data associated with C1923, as this can provide insight into the conditions under which the code was set.
   • If the scan tool allows, monitor VAPS solenoid commanded state and actual circuit voltage or duty cycle. A “short to battery” would typically show a high voltage reading on the control circuit when a lower voltage or specific duty cycle is commanded.
2. VAPS Solenoid Actuator Circuit Testing (Key Off, Disconnected):
   • Disconnect the electrical connector from the VAPS solenoid actuator.
   • Using a Digital Multimeter (DMM) set to resistance (ohms), test for a short to battery positive. Place one lead of the DMM on the VAPS solenoid control terminal (the signal wire from the control module) within the harness connector, and the other lead on the vehicle’s battery positive terminal. A reading close to 0 ohms or very low resistance indicates a direct short to battery in the wiring harness. If there’s no short, the reading should be open circuit (OL).
   • Next, test the solenoid itself. Measure the resistance across the two terminals of the VAPS solenoid actuator (if applicable; some designs have internal resistance that can be checked this way). Compare the reading to the manufacturer’s specifications. An open circuit or a very low resistance (near 0 ohms) could indicate an internal fault within the solenoid.
3. VAPS Solenoid Actuator Circuit Testing (Key On, Disconnected):
   • With the VAPS solenoid actuator still disconnected from its harness connector, turn the ignition to the “ON” position (engine off).
   • Using the DMM set to DC volts, measure the voltage on the VAPS solenoid control wire (the signal wire from the control module) within the harness connector, relative to a known good ground. If C1923 is present and indicates a “short to battery,” this wire will likely show battery voltage (e.g., 12V-14V), even when the control module is not commanding it to do so. This confirms a short in the wiring harness or an internal fault within the control module itself.
4. Control Module Isolation Test:
   • If the voltage test above indicates a short, and the wiring harness appears intact, consider the possibility of an internal module fault. Disconnect the electrical connector(s) from the PSCM/PCM (or the specific module controlling the VAPS).
   • Retest for the short to battery on the VAPS control wire at the harness connector (now disconnected from the module). If the short disappears (i.e., you no longer read battery voltage or low resistance to B+), the fault is likely internal to the control module. If the short persists, the fault is definitively in the wiring harness between the module and the VAPS solenoid.

Recommended Repairs and Solutions

• Repair or Replace Damaged Wiring: The most frequent resolution for C1923 involves locating and repairing the specific section of the wiring harness that is shorting to battery voltage. Use high-quality heat-shrink butt connectors or solder for durable repairs. Ensure the repaired section is properly re-routed and secured to prevent future chafing or damage.
• Replace VAPS Solenoid Actuator: If testing confirms an internal short or incorrect resistance within the VAPS solenoid actuator itself, replacement is necessary. Always use an OEM-equivalent part for optimal performance and longevity.
• Clean or Replace Corroded Connectors: If corrosion is found, use an electrical contact cleaner and a small brush to thoroughly clean the terminals. If the corrosion is severe or the terminals are damaged, consider replacing the connector pigtail.
• Replace Power Steering Control Module (PSCM) or PCM: This should be a last resort after all external wiring and component checks have definitively ruled out other causes. If the control module is determined to be at fault, ensure proper programming or calibration is performed after installation, as required by the vehicle manufacturer.
• Mechanic’s Tips:
  • Always refer to the vehicle-specific wiring diagrams and service manuals for precise wire colors, pin locations, and component specifications.
  • After any repair, clear the DTCs with a scan tool and perform a road test under various conditions (especially different speeds) to confirm the repair and ensure the variable assist function is restored and no new codes are set.
  • Inspect for any power steering fluid leaks around the VAPS solenoid or power steering pump, as these could potentially lead to electrical component degradation over time.