Code
P1484
HUMMER
P — Powertrain
Cooling Fan System Performance
Views:
UK: 19
EN: 25
RU: 37
AI status
Completed
Completed
100%
Causes
- Faulty cooling fan motor or fan assembly
- Failed fan control module or PCM output
- Open/shorted wiring or poor connector/ground to fan(s)
- Blown fuse or faulty fan relay
- Low battery/charging system voltage
- Obstructed fan blades or debris in shroud/condenser
Symptoms
- Engine temperature higher than normal or intermittent overheating
- Cooling fan(s) do not run or run intermittently when commanded
- Reduced air conditioning performance at low speeds or idle
- Illuminated check engine light (CEL) with stored P1484
- Cooling fan runs continuously or at incorrect speeds
What to check
- Read PCM/BCM freeze frame and full DTC report with a scan tool and note conditions when code set
- Perform an active test (command fan on/off and different speed levels) with a scan tool and observe response
- Visually inspect fan blades, shroud, and condenser for obstructions or damage
- Check fan fuses and relays for correct operation and proper contacts
- Measure voltage at fan motor connector while commanding fan on (should be near battery voltage when full on)
- Check continuity and resistance of fan motor circuit and ground connections
Signal parameters
- Commanded fan state (ON/OFF) and PWM duty cycle (%) from PCM/fan module
- Fan motor supply voltage: ~11–14.5 V when commanded on
- Fan motor current draw: within manufacturer specification (amps)
- Fan speed (RPM) or expected speed range when commanded
- Engine coolant temperature (°C or °F) at fault
- A/C refrigerant pressure (if fan requested for A/C) and A/C request status
Diagnostic algorithm
- Connect a professional scan tool, record freeze frame data and confirm P1484 is current. Note engine temp, vehicle speed, A/C status, and battery voltage at the time of the fault.
- Perform an active test to command the cooling fan(s) ON and OFF; observe whether fan(s) respond. If fan responds normally to command, suspect intermittent wiring, connector, or sensor issue.
- With fan commanded ON, measure voltage at the fan motor power terminal and ground at the connector. If voltage is present and fan does not run, suspect bad fan motor or internal mechanical fault.
- If voltage is absent or low when commanded, check fan fuses, relays, and control module outputs. Backprobe the control output and confirm PCM or fan module is commanding correctly (voltage or PWM).
- Inspect wiring and connectors for corrosion, damaged insulation, high-resistance connections, or poor ground. Wiggle harness while commanding fan to check for intermittent faults.
- Measure fan motor current draw and resistance. High resistance or high current indicates mechanical drag or short; open circuit indicates motor winding failure.
- Check related sensors (ECT, A/C pressure switch) and verify they show reasonable values in live data; replace if they provide incorrect inputs that could affect fan logic.
- Repair or replace failed components (fan motor/assembly, relay, fuse, harness, fan control module) as indicated by tests. Clear codes and perform a road/idle test to verify the system operates under the original conditions and code does not return.
- If diagnosis is inconclusive or intermittent, monitor vehicle under similar conditions that produced the freeze frame, and consider extended data-logging or module bench testing.
Likely causes
- Bad fan motor or fan control module
- Open or high-resistance ground or power feed to the fan
- Faulty fan relay or fuse
- Low battery/charging voltage under load
- Physical obstruction or seized fan bearings
Fault status
Status
Cooling Fan System Performance fault — the control system detected the cooling fan(s) are not performing to commanded requirements (speed, on/off, or duty). This can cause reduced cooling and possible engine overheating or poor A/C operation.
Repair difficulty: Medium
Diagnostic time: 0.5-2.0 hours
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