Case IH 3654 – Engine Control Unit (ECU) / EDC: Charge Air cooler : Difference between measured and calculated temperature

The engine control system calculates an expected charge air temperature based on ambient conditions, engine load, and boost pressure. If the actual temperature reported by the Charge Air Cooler (CAC) temperature sensor deviates significantly from this mathematical model, the system flags this code. This typically indicates a skewed temperature sensor, a wiring issue, a boost leak, or a physically restricted/failing charge air cooler.

• Magnum 215
• Magnum 245
• Magnum 275
• Magnum 305
• Magnum 335
• Steiger/STX series
• Puma series
• Maxxum series
• Axial-Flow 5088
• Axial-Flow 6088
• Axial-Flow 7088
• Axial-Flow 7130
• Axial-Flow 7230
• Axial-Flow 8230
• Axial-Flow 9230
• Patriot 4420
• Miller Atlas

1. 1

   Cold Engine Sensor Verification: Using a diagnostic scan tool, read the CAC temperature sensor value when the engine has been sitting overnight and is completely cold. It should closely match the ambient air temperature and the engine coolant temperature. If the reading is skewed, the sensor is likely faulty.

2. 2

   Wiring and Connector Inspection: Inspect the wiring harness leading to the CAC temperature sensor. Look for chafed wires, melted insulation, or corrosion inside the connector pins that could cause high resistance and alter the sensor's voltage signal.

3. 3

   Boost Leak Test: Inspect all charge air cooler piping, rubber boots, and clamps. A boost leak alters the pressure and temperature dynamics of the intake air, which can trigger this code. Look for soot trails, oil residue around connections, or listen for hissing under load.

4. 4

   Charge Air Cooler Visual Inspection: Check the exterior fins of the charge air cooler for blockages caused by dirt, chaff, or debris. A blocked cooler cannot dissipate heat effectively, causing higher-than-calculated intake temperatures. Also, inspect the aluminum core for hairline cracks.

1. 1

   Prepare machine

   Park the machine on a level surface, turn off the engine, remove the key, and allow the engine to cool completely.

2. 2

   Clean charge air cooler

   Clean the exterior of the charge air cooler. If the fins are packed with field debris, use compressed air or a specialized foaming cooler cleaner to clear the blockage and restore airflow.

3. 3

   Repair boost leak

   If a boost leak was identified during diagnostics, loosen the T-bolt clamps, remove the damaged rubber boost hose, and install a new hose. Torque the clamps to the manufacturer's specification to ensure a tight seal.

4. 4

   Replace CAC temperature sensor

   If the sensor failed the cold-engine test, locate the sensor (typically mounted on the charge air cooler outlet pipe or the intake manifold). Disconnect the electrical pigtail, unthread the faulty sensor, and install the replacement.

5. 5

   Replace charge air cooler

   If the charge air cooler core is cracked or internally restricted, it must be replaced. Remove the inlet and outlet boost tubes, unbolt the cooler mounting brackets, and lift the unit out of the cooling package. Drop the new OEM charge air cooler into place and reconnect the piping.

6. 6

   Clear code and test

   Reconnect your diagnostic tool, clear the 3654 fault code from the EDC, and test drive the machine under working load to ensure the code does not return.