Electric cooling fan. Radiator coolant flow check

Electric cooling fan

The powertrain control module (PCM) will set a diagnostic trouble code (DTC) in memory if it detects a problem in the electric cooling fan relay or circuit.

Refer to On-Board Diagnostics in Group 25, Emission Control Systems for more information on accessing a DTC.

The DTC can also be accessed through the DRB scan tool. Refer to the appropriate Powertrain Diagnostic Procedures manual for diagnostic information and operation of the DRB scan tool.

Radiator coolant flow check

Equipment Required:

• DRB Scan Tool
• Volt/Ohm meter
• Wiring Diagrams section of this manual

Fig. 19 Electrical Cooling Fan

1 - RADIATOR

2 - ELECTRIC FAN ASSEMBLY

3 - FAN SHROUD (LOWER)

4 - SCREW

Test Procedure:

1) Inspect 10A fuse in junction block and 40A maxi fuse in PDC (Fig. 20).

(2) Remove Cooling Fan Relay from the PDC and make the following checks at the relay connector:

• Apply 12 volts (using a fused 14-gauge wire) to circuit C25 (relay terminal 87). If fan does not come on, check for open in circuit C25 or Z1. If circuits are o.k., replace the cooling fan motor.
• With the ignition key "off" check for battery voltage at circuit C28 (relay terminal 30). If no battery voltage present check for open/shorted circuit C28 between the PDC and relay.
• With the ignition key in the "run" position check for battery voltage at circuit F18 (relay terminal 86).

  If no battery voltage present, check for open/short in circuit F18 between the junction block and the relay.

• If no problems are detected, install the DRB (refer to the appropriate Powertrain Diagnostic Procedures manual for DRB scan tool operating instructions) and start the engine. Clip a 12V test light to the battery positive terminal and probe circuit C27 (relay terminal 85). When the engine temperature reaches 110 C (230 F), or A/C is requested, the test light should light. If not, check circuit C27 for open.
• If no problems are detected at this point, replace the cooling fan relay.

Fig. 20 Power Distribution Center (PDC)

1 - POWER DISTRIBUTION CENTER (PDC)

RADIATOR COOLANT FLOW CHECK

Use the following procedure to determine if coolant is flowing through cooling system.

(1) Idle engine until operating temperature is reached. If upper radiator hose is warm to the touch, thermostat is opening and coolant is flowing to radiator.

WARNING: HOT, PRESSURIZED COOLANT CAN CAUSE INJURY BY SCALDING. USING A RAG TO COVER RADIATOR PRESSURE CAP, OPEN RADIATOR CAP SLOWLY TO FIRST STOP. ALLOW ANY BUILT-UP PRESSURE TO VENT TO THE RESERVE/ OVERFLOW TANK. AFTER PRESSURE BUILD-UP HAS BEEN RELEASED, REMOVE CAP FROM FILLER NECK.

(2) Drain a small amount of coolant from radiator until ends of radiator tubes are visible through filler neck. Idle engine at normal operating temperature. If coolant is flowing past exposed tubes, coolant is circulating.