Yale 105-4 – Engine Control Unit (ECU): Intake Air Temperature (IAT) Sensor OORL

The sensor voltage signal is abnormally low or non-existent. This indicates the sensor signal is shorted to the sensor ground or frame ground, the sensor has suffered an internal failure, or there is a functional failure in the controller.

• Yale and Hyster Forklifts
• Yale and Hyster forklifts (2005 and newer models)

1. 1

   Check the IAT sensor, connector, and wiring harness for physical damage, loose connections, or exposure to contamination.

2. 2

   Inspect the wiring harness for open circuits or shorts to ground.

3. 3

   Inspect the connector terminals for corrosion.

4. 4

   Use a multimeter to check if the resistance readings of the IAT sensor are out of specification.

5. 5

   Verify the controller's sensor input voltages to rule out a faulty controller.

1. 1

   Disconnect Power

   Disconnect the battery before doing any maintenance or repair on the lift truck.

2. 2

   Secure Connections

   Inspect and secure the connections between the wiring harness and the IAT sensor. Clean any corrosion found on the connector terminals.

3. 3

   Repair Wiring

   If the wiring harness is found to be shorted to ground or has an open circuit, repair or replace the affected wiring.

4. 4

   Replace Sensor

   If the wiring is intact but the sensor's resistance readings are out of spec, disconnect the wiring harness connector from the sensor and remove the faulty IAT sensor. Install the new OEM IAT sensor and reconnect the harness.

5. 5

   Restore Power

   Reconnect the battery.

6. 6

   Verify Fix

   Clear/reset the error codes and monitor the sensor data live to verify the fix.

7. 7

   Controller Replacement

   If the issue remains after replacing the sensor and verifying the wiring, test the controller inputs. Replace the controller only if it is proven defective.