Understanding Lincoln OBD2 Code P1473: Fan Control Secondary Circuit
When your Lincoln’s Powertrain Control Module (PCM) triggers diagnostic trouble code (DTC) P1473, it indicates a specific electrical fault within the vehicle’s critical engine cooling system. Code P1473 is defined as “Fan Control Secondary Circuit.” This code is specific to Ford Motor Company vehicles, including Lincoln models, and points to a malfunction in the secondary control circuit for the engine cooling fan(s). Unlike primary fan codes, P1473 often relates to a multi-fan setup, a dedicated high-speed circuit, or a secondary control path managed by the PCM. Ignoring this code can lead to insufficient cooling, potential engine overheating, and severe engine damage, making timely diagnosis and repair essential for your Lincoln’s health and performance.
Common Symptoms and Potential Causes of P1473 in Your Lincoln
The manifestation of code P1473 is directly tied to the compromised cooling fan operation. Recognizing the symptoms is the first step in confirming the code’s impact.
Primary Symptoms of a P1473 Fault
- Illuminated Check Engine Light (CEL): The most immediate indicator, storing code P1473 in the PCM’s memory.
- Cooling Fan Operational Issues: The secondary fan may not activate at all, may run continuously, or may not engage at high speed when demanded (e.g., during A/C use or high engine load).
- Engine Overheating or Higher Operating Temperatures: Especially noticeable in traffic, during idle, or in hot weather due to inadequate airflow through the radiator.
- Reduced Air Conditioning Performance: The A/C system may blow warm air or disengage because the condenser fan (often tied to this circuit) fails to run.
Root Causes of the P1473 Diagnostic Trouble Code
The PCM monitors the voltage and current in the secondary fan control circuit. A value outside the expected range triggers P1473. The fault can originate from several points in the circuit.
- Faulty Cooling Fan Motor (Secondary): A seized, worn-out, or electrically open fan motor.
- Failed Fan Relay or Control Module: A burnt-out relay responsible for the secondary circuit or a malfunction in a dedicated fan control module.
- Damaged Wiring or Connectors: The most common cause. This includes:
- Open circuits (broken wires).
- Short circuits to power or ground (chafed wiring).
- Corroded or loose electrical connectors at the fan, relay, or PCM.
- Blown Fuse: A dedicated fuse for the secondary fan circuit may be blown, often due to a downstream short.
- Faulty Powertrain Control Module (PCM): While less common, an internal failure of the PCM’s driver circuit for the fan can set this code. This should be a last-resort diagnosis.
Step-by-Step Diagnostic Procedure for Code P1473
A systematic approach is crucial to correctly identify the faulty component. Always begin with a visual inspection and work from the simplest to the most complex causes. Warning: Ensure the engine is cool and the ignition is OFF before handling electrical components.
Step 1: Preliminary Visual and Basic Checks
Start with a thorough inspection. Look for obvious signs of damage in the engine bay, particularly around the fan shroud and wiring harnesses.
- Locate and inspect the secondary cooling fan. Check for physical obstruction or damage.
- Find the cooling fan relay(s) and fuse(s) in the under-hood fuse/relay box. Consult your Lincoln owner’s manual for their exact location. Visually inspect the fuse and listen/feel for the relay clicking when the A/C is turned on MAX.
- Trace the wiring harness from the fan motor to the relay and PCM. Look for chafing, burns, melted insulation, or corrosion at all connectors.
Step 2: Electrical Testing of the Fan Motor and Circuit
If visual checks reveal nothing, proceed with a digital multimeter (DMM).
- Test the Fan Motor: Disconnect the fan motor connector. Apply direct 12-volt power and ground from the battery to the motor terminals (observing polarity). If the fan does not run, the motor is faulty.
- Check for Power and Ground: With the connector back on and the ignition in RUN (engine may be off), command the secondary fan on using a professional scan tool. Probe the power and ground wires at the fan connector. You should read battery voltage (~12V) when commanded. If not, the issue is upstream.
Step 3: Testing the Relay, Wiring, and PCM Signal
This step isolates the fault between the relay and the PCM.
- Relay Test: Swap the suspected secondary fan relay with an identical, known-good relay (e.g., horn relay). If the problem moves, replace the relay.
- Continuity and Short Tests: With the battery disconnected, use the DMM’s continuity/resistance setting. Check for open circuits (infinite resistance) in the wires between the relay socket and the fan, and between the relay socket and the PCM connector. Also check for shorts to ground or power.
- PCM Command Signal: Using a scan tool with bidirectional controls or a noid light, verify the PCM is sending the ground signal to activate the relay when commanded. If power and ground are present at the relay socket but the PCM signal is missing, a PCM issue is more likely.
Repair Solutions and Important Considerations
Once the faulty component is identified, the repair path becomes clear. Always clear the code with an OBD2 scanner after repairs and perform a test drive to ensure it does not return.
Common Repair Procedures
- Replacing the Cooling Fan Motor/Assembly: Unbolt the fan shroud assembly, disconnect the electrical connector, and install the new unit. Ensure proper fitment to avoid interference with the radiator.
- Repairing Wiring Harnesses: For damaged wires, cut out the bad section, solder in a new piece of gauge-appropriate wire, and protect with heat-shrink tubing. Never use twist connectors in automotive environments.
- Replacing Relays and Fuses: Use only OEM-specification relays. When replacing a fuse, it is critical to diagnose why it blew first to prevent immediate recurrence.
- Cleaning Electrical Connectors: Use electrical contact cleaner and a small brush to remove corrosion from pin connectors.
Professional Insight and Final Verification
Given the complexity of modern cooling systems, which are integral for engine performance and emissions, a professional-grade scan tool is highly beneficial for commanding components during testing. If all wiring, relays, fuses, and the fan motor test correctly, and the PCM command signal is verified missing, a PCM fault may be the cause. Reprogramming or replacement of the PCM is a highly technical task best left to a qualified technician or dealership. After any repair, monitor the engine temperature gauge and use your scanner to watch the live data parameter for fan command to confirm the system is operating as designed under various conditions.