Test B: The Engine Overheats

Pinpoint Test B: The Engine Overheats

Normal Operation
Under normal operation, the battery Junction box (BJB) supplies constant power to the low speed engine cooling fan relay through fuse F1.2 (30A) and to the high speed cooling fan relay through fuse F1.6 (50A). The PCM provides the ground through the engine cooling fan resistor on circuit 15S-PA2 (GN/BU) for the low speed engine cooling fan relay on circuit 15S-PA9 (GN/WH) and also the high speed engine cooling fan relay on circuit 15S-PA1 (GN/BU).

Possible Causes
^ Engine coolant loss
^ Towing weight exceeded
^ System restriction
^ Blocked radiator grille
^ Thermostat
^ Fuse(s):
- F1.2 (30A) low speed
- F1.6 (50A) high speed
^ Circuitry
^ Cooling fan motor
^ Coolant pump
^ Accessory drive belt
^ Cylinder head temperature (CHT) sensor
^ Powertrain control module (PCM)

B1-B4:

PINPOINT TEST B: THE ENGINE OVERHEATS