Air Suspension Warning Light Circuit Open
The C1851 code indicates an open circuit in the electrical system that controls the air suspension warning light on the dashboard. The suspension control module detects a loss of continuity in the circuit that powers or receives the signal from the warning light. This is a manufacturer-specific chassis code (C1xxx) commonly associated with Ford and Lincoln vehicles equipped with air suspension. When the module tries to activate the warning light to alert the driver of a suspension fault, it cannot complete the electrical circuit.
1. Commonly Affected Makes
2. Most Common Causes
- Burnt-out bulb or LED in the instrument cluster
- Broken or disconnected wiring between the suspension module and the dashboard
- Loose or corroded connector at the instrument cluster
- Blown fuse in the warning light circuit
3. Symptoms You Will Notice
- Air suspension warning light does not illuminate when the key is turned on
- Warning light stays off even when a suspension fault is present
4. Step-by-Step Diagnosis
Check the warning light bulb or LED in the instrument cluster for continuity
Inspect the wiring and connectors between the suspension module and the dashboard for damage or corrosion
Test the fuse for the warning light circuit
Verify the suspension control module's output to the warning light using a scan tool or multimeter
5. Frequently Asked Questions
Is it safe to drive?▼
Yes, the vehicle is generally safe to drive, but you may not be alerted to a suspension fault. Have it diagnosed soon.
How much does it cost to fix?▼
Typically $100 to $300, depending on whether it's a bulb, wiring repair, or module replacement.