Checking Engine Cooling Fan

Symptoms
- Ignition OFF.

Check Engine Cooling Fan Speed
- If the engine cooling fan operates at low-speed even when the ignition is OFF: Select 1.
- If the engine cooling fan operates at high-speed even when the ignition is OFF: Select 2.
- If neither of the above symptoms apply: Select 3.
- Select a suitable alternative.

Alternative 1:
^ Proceed to: Checking the Fan Control Relay, Half Speed section below.

Alternative 2:
^ Proceed to: Checking Engine Cooling Fan Relay, High-Speed section below.

Alternative 3:
^ Proceed to: Checking Engine Cooling Fan section below.





Checking Engine Cooling Fan
- Check engine cooling fan. Refer to: Activating Components / Functions, cooling fan operates at low-speed and high-speed.
- If the engine cooling fan works at both speeds: Select OK.
- If the engine cooling fan only works at low-speed: Select 1.
- If the engine cooling fan only works at high-speed: Select 2.
- If the engine cooling fan does not run at all: Select 3.
- Select a suitable alternative.

If reading is OK:
^ The fault is intermittent.

Alternative 1:
^ Proceed to: Checking Signal Cable, High-Speed section below.

Alternative 2:
^ Proceed to: Checking the Blower Fan Motor, Low-Speed Side section below.

Alternative 3:
^ Proceed to: Checking the Engine Cooling Fan Motor section below.





Checking Signal Cable, High-Speed
- Connect the breakout box and check ground terminals.
- Disconnect connector B from engine cooling fan relay.
- Connect an ohmmeter between connector B terminal 2 and # 22 (# A22) on the breakout box.
- Does the ohmmeter read approx. 0 ohms?

Yes:
^ Proceed to: Checking the Engine Cooling Fan Motor, High-Speed section below.

No:
^ Check cable between engine cooling fan relay terminal B2 and engine control module (ECM) # A22 for an open-circuit.





Checking the Engine Cooling Fan Motor, High-Speed
- Ignition OFF.
- Disconnect connector C from engine cooling fan relay.
- Connect an ohmmeter between connector C terminal 2 and ground.
- Does the ohmmeter read 0 - 10 ohms?

Yes:
^ Try a new engine cooling fan relay.

No:
^ Try a new engine cooling fan.





Checking the Blower Fan Motor, Low-Speed Side
- Ignition OFF.
- Disconnect connector C from engine cooling fan relay.
- Connect an ohmmeter between connector C terminal 1 and ground.
- Does the ohmmeter read 0 - 10 ohms?

Yes:
^ Try a new engine cooling fan relay.

No:
^ Try a new engine cooling fan.





Checking the Engine Cooling Fan Motor
- Ignition OFF.
- Disconnect connector C from engine cooling fan relay.
- Connect an ohmmeter between connector C terminal 2 and ground.
- Does the ohmmeter read 0 - 10 ohms?

Yes:
^ Try a new engine cooling fan relay.

No:
^ Proceed to: Checking Ground Terminal section below.





Checking Ground Terminal
- Ignition OFF.
- Disconnect connector C from engine cooling fan relay.
- Check engine cooling fan ground terminal (31/64) for contact resistance and oxidation and remedy.
- Connect an ohmmeter between connector C terminal 2 and ground.
- Does the ohmmeter read 0 - 10 ohms?

Yes:
^ The cause of the engine cooling fan not working has been loose connections in the engine cooling fan ground terminal.

No:
^ Try a new engine cooling fan.





Checking the Fan Control Relay, Half Speed
- Ignition OFF.
- Disconnect connector B from engine cooling fan relay.
- Does the engine cooling fan cut out?

Yes:
^ Check cable between engine cooling fan relay terminal B1 and engine control module # A7 for a short-circuit to ground.

No:
^ Try a new engine cooling fan relay.





Checking Engine Cooling Fan Relay, High-Speed
- Ignition OFF.
- Disconnect connector B from engine cooling fan relay.
- Does the engine cooling fan cut out?

Yes:
^ Check cable between engine cooling fan relay terminal B2 and engine control module # A22 for a short-circuit to ground.

No:
^ Try a new engine cooling fan relay.