Cooling Fan System Operation (At Idle)

WARNING: This page is about a different car, the 2004 Mazda RX-8. However, it is still accessible from the selected car via links, so may be relevant.

Fig 1: Cooling Fan System Operation At Idle

Courtesy of MAZDA MOTORS CORP.

Connect the WDS or equivalent to the DLC-2.
Verify that DTC P0480 or P0481 is not displayed.
- If DTC P0480 and/or P0481 are displayed, perform DTC inspection.
Access the ECT PID.
Verify that the ECT PID is 97°C {208°F} or less.
Verify that the A/C switch and fan switch are off.
Start the engine and let it idle.
Verify that the cooling fans are not operating.
- If the cooling fans are operating at low speed, inspect for the following:
  - Cooling fan relay No. 1 (stuck closed)
  - Wiring harnesses and connectors (cooling fan relay No. 1-PCM terminal 5X) (short to GND)
- If the cooling fan No. 1 is not operating, but cooling fan No. 2 is operating, inspect for the following:
  - Cooling fan relay No. 3 (stuck closed)
  - Wiring harnesses and connectors (cooling fan relay No. 3-PCM terminal 5AD) (short to GND)
Warm up engine 97°C {208°F} or more and verify that the cooling fans are operating at low speed.
- If cooling fans are not operating, inspect for the following:
  - Cooling fan relay No. 1 (stuck open)
  - Wiring harnesses and connectors (battery-cooling fan relay No. 1-cooling fan relay No. 2) (open)
  - Wiring harnesses and connectors (main relay-cooling fan relay No. 1 PCM terminal 5X) (open)
- If cooling fan relay No. 1 is operating at high speed, inspect for the following:
  - Cooling fan relay No. 2 (stuck close)
Stop the engine.
Disconnect the ECT sensor.
NOTE:
- When the ECT sensor connector is disconnected, the PCM stores DTC P0118.
Start the engine and let it idle.
Verify that the cooling fans are operating at high speed.
- If the cooling fans are operating at low speed, inspect for the following:
  - Cooling fan relay No. 2 (stuck open)
  - Cooling fan relay No. 3 (stuck open)
  - Wiring harnesses and connectors (open circuit at battery-cooling fan relay No. 3-cooling fan No. 2-GND)
  - Wiring harnesses and connectors (open circuit at main relay-cooling fan relay No. 2-PCM terminal 5AD)
  - Wiring harnesses and connectors (open circuit at main relay-cooling fan relay No. 3-PCM terminal 5AD)
- If cooling fan No. 1 is operating at high speed, but cooling fan No. 2 is not operating, inspect for the following:
  - Cooling fan relay No. 3 (stuck open)
  - Wiring harnesses and connectors (open circuit at main relay-cooling fan relay No. 3-PCM terminal 5AD)
- If cooling fan No. 1 is operating at high speed, but cooling fan No. 2 is not operating, inspect for the following:
  - Cooling fan relay No. 3 (stuck open)
  - Wiring harnesses and connectors (open circuit at main relay-cooling fan relay No. 2-PCM terminal 5AD)
Clear the DTC from the PCM memory.