P028D

Code

Generic P — Powertrain

Charge Air Cooler Cooling Fan Control Circuit Low

Brand: Generic

Type: P — Powertrain

Views: UK: 25 EN: 66 RU: 28

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Malfunction Indicator Lamp (MIL/CEL) illuminated
Charge air cooler / intercooler fan does not run when commanded
Intercooler or inlet air temperature higher than normal under load
Reduced engine performance or possible derate in some vehicles
Unusual fan behavior (runs continuously, not at commanded speed, or intermittent)

Confirm freeze frame data and whether the code is current or historic using a scan tool
Visually inspect wiring harness, connectors, and fan for damage or corrosion
Check fuses and relays related to the charge air cooler fan circuit
Use a scan tool to command the fan on/off and observe response
Measure voltage at the fan power and control pins with fan commanded on and off
Check continuity and resistance between ECM control pin and fan connector

Control circuit off (no PWM): ~battery voltage (approx. 11–14.5 V) on the control pin if the driver is low-side (pull-up present) — consult vehicle manual
Control circuit on (driver switching to ground): ~0 V on the control pin for low-side drivers
PWM control: duty cycle 0–100% as commanded by ECM; frequency commonly in the tens to a few hundred Hz (vehicle-specific)
Fan motor supply: steady battery voltage (11–14.5 V) at the fan power supply lead
Fan running current: typically several amps (varies widely by vehicle); measure with appropriate clamp meter or consult spec

Read and record freeze frame data and other DTCs. Confirm code P028D is present and note conditions when set.
Visually inspect the fan, connector, and wiring along the routing to the ECM for damage, corrosion, chafing, or water intrusion.
With ignition on, use a scan tool to command the intercooler fan on while observing connector pins and verifying a change on the control circuit.
Measure pin voltages at the fan connector: with fan commanded off and on. Compare to expected values (see signal_params) and manufacturer specs.
Check continuity and resistance between the ECM control pin and the fan connector; look for short to ground or open circuit.
Verify power supply and ground at the fan: check fuse(s), relay function, and battery/ground connections.
Bench-test the fan motor by applying direct 12 V to the motor supply and ground to ensure the motor runs and does not draw excessive current.
If the fan motor and wiring are good, test/replace the relay or fan driver module if equipped. If the control output is still abnormal and wiring checks good, suspect ECM output driver — refer to manufacturer repair procedures before replacing ECM.
After repairs, clear codes and re-test under the same conditions to confirm the fault is resolved.

Wire insulation chafed and shorting to chassis ground near the intercooler or fan
Connector corrosion at the fan motor or ECM
Failed integrated fan control module (internal MOSFET/driver)
Blown fuse or relay contacts stuck closed/open
Damaged ground strap or poor battery connection