CM850 Electronic Control System – Intake Manifold Air Temperature Above Specification

Fan drive belt is broken

Check the fan drive belt. Replace the belt, if necessary. Refer to Procedure 008-002 in the Troubleshooting and Repair Manual, ISC, QSC8.3, ISL and QSL9 Engines, Bulletin 4021418.

Fan drive belt is loose

Check the belt tension and tighten if necessary. Refer to Procedure 008-002 in the Troubleshooting and Repair Manual, ISC, QSC8.3, ISL and QSL9 Engines, Bulletin 4021418.

Cold weather radiator cover or winterfront is closed

Open the cold weather radiator cover or the winterfront. Maintain a minimum of 387 cm² [60 in²] of opening at all times. Refer to Operation of Diesel Engines in Cold Climates, Service Bulletin 3379009.

Charge air cooler fins, radiator fins, or air conditioner condenser fins are damaged or obstructed with debris

Inspect the charge air cooler, air conditioner condenser, and radiator fins. Clean, if necessary. Refer to Procedure 010-027 in the Troubleshooting and Repair Manual, ISC, QSC8.3, ISL and QSL9 Engines, Bulletin 4021418.

Intake manifold temperature gauge is malfunctioning, if equipped

Test the temperature gauge. Refer to the OEM service manual.

Electronic fault codes active or high counts of inactive fault codes

Refer to Section TF for fault code troubleshooting.

Programmable parameters or selected features are not correct

Check the programmable parameters and the selected features with an electronic service tool. Set the parameters and features again if necessary. Refer to Procedure 019-078.

Fan drive or fan controls are malfunctioning

Check the fan drive and controls. Refer to Procedure 019-045.

Fan is not correct

Check the fan part number and compare it to the OEM-specified part number. Replace fan if necessary. Refer to the OEM service manual.

Fan shroud is damaged or missing or the air recirculation baffles are damaged or missing

Inspect the shroud and the recirculation baffles. Repair, replace, or install, if necessary. Refer to Procedure 008-038 in the Troubleshooting and Repair Manual, ISC, QSC8.3, ISL and QSL9 Engines, Bulletin 4021418.

Vehicle speed is too low for adequate cooling with high engine load

Reduce the engine load. Increase the engine (fan) rpm by downshifting.

Intake manifold pressure sensor is malfunctioning

Check the intake manifold pressure sensor. Refer to Procedure 019-061.

Vehicle cooling system is not adequate

Verify that the engine and vehicle cooling systems are using the correct components. Refer to the OEM service manual.

Fan is not an adequate size for the application

Verify that the fan is the correct size. Refer to the OEM service manual.