P1109

Code

FIAT P — Powertrain

Electric fan assembly 2 fault

Brand: FIAT

Type: P — Powertrain

Views: UK: 5 EN: 9 RU: 10

AI status

Completed

ready

Completed 100%

Page language: EN

Causes

Blown fuse or faulty fan relay for fan assembly 2
Open, shorted, corroded or damaged wiring/connectors to the fan motor
Failed fan motor or internal fan assembly electronics
Poor ground connection at fan or chassis
Faulty engine control/module output or driver transistor
Mechanical obstruction or seized fan

Symptoms

Cooling fan 2 does not run when expected (engine hot or A/C on)
Reduced A/C cooling performance
Engine temperature higher than normal / possible overheating
Fan runs continuously or runs at incorrect speeds
MIL/Check Engine Light illuminated and P1109 stored
Unusual noise or grinding from fan area

What to check

Read/record all stored codes and freeze-frame data with a scan tool
Visually inspect fan 2 wiring, connector and harness for damage/corrosion
Check relevant fuses and fan relay(s); swap relay with a known-good relay if available
Verify fan 2 connector voltage and ground with ignition on and while commanding fan via scan tool
Back-probe control and power circuits while commanding fan to run
Measure motor resistance and compare to specification (consult service manual)

Signal parameters

Battery/supply voltage to fan motor: ~11–14 V with engine running (varies by system)
Control signal: either direct switched battery (on/off) or PWM from module (duty cycle varies 0–100%)
Control signal frequency for PWM systems: typically tens to a few hundred Hz (consult OEM data)
Expected fan motor current draw: varies by vehicle (commonly single-digit to tens of amps); abnormal high current indicates binding/short, near-zero indicates open circuit
Resistance of fan motor windings: low ohms (consult service data for exact value)

Diagnostic algorithm

Connect a professional scan tool, read stored and pending codes, note freeze-frame and related codes (e.g., coolant temp, A/C).
Attempt to command fan 2 ON via scan tool with ignition on; observe behavior and any change to trouble code status.
With fan commanded ON, measure voltage at the fan motor power pin and at the control pin (back-probe connector). Confirm battery voltage presence and proper control signal.
Check continuity to ground from fan ground pin; look for high resistance or intermittent grounding.
Inspect and test the fan relay and fuse. Replace if faulty or swap with identical relay to confirm.
Visually inspect connector pins for corrosion, bent pins or water ingress; repair or replace connector as needed.
Measure motor winding resistance and bench test motor by applying battery voltage directly (use appropriate fusing and safety). If motor does not run or draws excessive current, replace the fan assembly.
If wiring, relay, fuse and motor test good, check the module output driver at the control module for opens/shorts or damaged driver circuits; consult OEM module test procedures before replacing module.
After repairs, clear codes and perform functional test under normal operating conditions (A/C on, engine at operating temperature) to confirm fault does not return.

Likely causes

Corroded or loose connector at fan motor
Failed fan motor or overheated motor driver inside assembly
Blown fuse or faulty fan relay
Open/short in supply or ground wiring
Faulty ECU/BCM driver (less common)
Mechanical interference preventing fan rotation

Fault status

⚠️ Status

Electric fan assembly 2 fault detected. Possible electrical fault, connector/cable issue, relay/fuse problem, motor failure or control module output error. Inspect wiring, connectors, relay/fuse and test motor/control signals.

🟡 Repair difficulty: Medium

⏱️ Diagnostic time: 1.0-3.0 hours

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