C1844

What Does Code C1844 Mean?

DTC C1844 indicates an Air Suspension Secondary Front Inflator Solenoid Output Circuit Failure. This code signifies that the Air Suspension Control Module (ASCM), or a dedicated suspension control unit, has detected an electrical fault within the circuit controlling the secondary inflator solenoid for the front air suspension. This particular solenoid is responsible for controlling the air flow into or out of the front air spring or air strut, often assisting in the fine-tuning of ride height or pressure adjustment, or serving as a redundant or auxiliary path for air in complex systems. The ASCM monitors the electrical characteristics of this circuit, including voltage, current, and resistance. When the module detects an open circuit, a short to ground, a short to voltage, or an out-of-specification resistance within the solenoid’s coil or its associated wiring, it registers C1844. This typically prevents the module from effectively controlling the front air suspension’s inflation or deflation via this secondary path, impacting the system’s ability to maintain optimal ride height and damping characteristics.

Common Symptoms

• Air Suspension Warning Light Illuminated: The primary indicator on the instrument cluster.
• Abnormal Front Ride Height: The vehicle may sag or lean excessively on one or both front corners, or fail to achieve the commanded ride height.
• Harsh or Unstable Ride Quality: Due to incorrect air spring pressure or compromised damping.
• Air Compressor Running Excessively: If the system attempts to compensate for a perceived pressure loss, or if the fault is intermittent.
• Audible Air Leaks: Although not a direct symptom of a circuit failure, it could be a secondary issue contributing to the system’s inability to maintain height, which might be erroneously attributed to the solenoid circuit.
• Vehicle Not Responding to Ride Height Adjustments: If equipped with manual adjustment features.

What Causes the Code C1844?

• Faulty Secondary Front Inflator Solenoid: The solenoid coil itself may have an internal open circuit, short circuit, or excessively high resistance, preventing proper operation.
• Damaged Wiring Harness: An open circuit (broken wire), a short to ground, or a short to voltage within the wiring connecting the ASCM to the secondary front inflator solenoid. This can be caused by chafing, pinching, corrosion, or physical damage.
• Corroded or Loose Electrical Connector: Poor connection at either the solenoid’s pigtail connector or the ASCM connector due to corrosion, bent pins, or improper seating.
• Blown Fuse: Although less common for a circuit output failure, a fuse protecting the solenoid’s power supply could be blown, indicating an upstream short or overload.
• Faulty Air Suspension Control Module (ASCM): An internal fault within the ASCM’s driver circuit for the secondary front inflator solenoid, though less frequent than external circuit issues.

How to Diagnose and Troubleshoot

A systematic diagnostic approach is essential for C1844:

1. Retrieve and Analyze DTCs and Freeze Frame Data: Use a diagnostic scanner capable of accessing the air suspension control module. Confirm C1844 is present and check for any related codes. Note freeze frame data, which can provide insights into system conditions when the fault occurred.
2. Visual Inspection: Begin by visually inspecting the entire wiring harness leading to the front air suspension secondary inflator solenoid. Look for signs of chafing, cuts, corrosion, or damage, especially where the harness passes through grommets or near moving components. Inspect the electrical connectors at the solenoid and the ASCM for corrosion, bent pins, or loose connections.
3. Solenoid Resistance Test: Disconnect the electrical connector from the secondary front inflator solenoid. Using a Digital Multimeter (DMM), measure the resistance across the solenoid terminals. Compare this reading to manufacturer specifications (typically a few ohms to tens of ohms). An open circuit (DMM displays “OL” or infinity) or a resistance significantly outside specifications indicates an internal solenoid fault.
4. Wiring Continuity Test: With the battery disconnected and both ends of the harness circuit disconnected (at the ASCM and the solenoid), test for continuity between the corresponding terminals at the ASCM connector and the solenoid connector. There should be very low resistance (typically < 0.5 ohms). Then, test each wire for continuity to ground and to battery positive. Any continuity to ground or battery voltage indicates a short circuit.
5. Voltage Supply and Ground Check at Solenoid Connector: Reconnect the battery. With the solenoid disconnected, use a DMM to check for proper voltage supply and ground at the solenoid’s harness connector (this may require commanding the solenoid on with a bi-directional scanner, or referencing wiring diagrams for constant power/ground). Ensure the voltage present matches battery voltage or the specified control voltage.
6. ASCM Output Test (if applicable): If your diagnostic scanner supports bi-directional control, attempt to command the secondary front inflator solenoid ON and OFF. While doing so, monitor the voltage output from the ASCM driver circuit at the ASCM connector. If the voltage does not change as commanded, or is absent, and the wiring to the solenoid is confirmed good, the ASCM may be faulty.

Recommended Repairs and Solutions

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

• Replace Faulty Secondary Front Inflator Solenoid: If the resistance test or direct voltage/current tests confirm an internal fault with the solenoid, replacement is necessary. Ensure the replacement part is specific to the vehicle’s make, model, and suspension configuration.
• Repair or Replace Damaged Wiring: If wiring issues (open circuit, short to ground, short to voltage) are identified, repair the damaged section using appropriate automotive-grade wire, heat-shrink tubing, and solder connections or proper crimp connectors. For extensive damage, harness replacement may be necessary.
• Clean and Secure Corroded or Loose Connectors: If connector issues are found, clean terminals thoroughly with electrical contact cleaner. Apply dielectric grease to prevent future corrosion. If terminals are damaged or bent, repair or replace the connector housing and terminals.
• Replace Blown Fuse: If a blown fuse is discovered, replace it with a fuse of the correct amperage. Investigate what caused the fuse to blow, as it often indicates an underlying short in the circuit.
• Replace Air Suspension Control Module (ASCM): This is a last resort. If all other components and wiring have been thoroughly tested and verified as functional, and the ASCM’s output for the solenoid circuit is confirmed faulty, the module itself will need replacement. Note that ASCM replacement often requires specific programming and/or calibration procedures using specialized diagnostic equipment.

After any repair, clear the DTCs from the ASCM memory using a diagnostic scanner. Perform a road test or operate the air suspension system through its various modes to ensure the repair is successful and the C1844 code does not return. A full ride height calibration may also be necessary depending on the system and the components replaced.