BLADE & BEARING AS 4252826 - Caterpillar

Illustration 1 g02883636
Air conditioner evaporator coil temperature sensor circuit (Freeze probe)This diagnostic code indicates the brake ECM has determined the air conditioner evaporator coil temperature sensor voltage is above normal.This code can be caused by:
Open sensor signal circuit
Shorted sensor signal circuit
Failed sensor
Failed power or ground circuit
Failed ECMNote: The following test procedure may create other diagnostic codes. Ignore these codes, correct the original code, then clear these created codes. Note: Use a calibrated digital multimeter for this procedure.Test Step 1. CHECK FOR POWER
Turn on the disconnect switch and the keyswitch.
Disconnect the harness connector from the sensor.
At the harness connector for the sensor, measure the voltage from power supply contact 1 and ground contact 2.Expected Result:The voltage is 0 TO 5 DCV.Results:
OK - The voltage is 0 TO 5 DCV. Proceed to Test Step 2.
NOT OK - The voltage is not 0 TO 5 DCV. The harness has failed.Repair: Replace or repair the harness.STOPTest Step 2. CHECK FOR GROUND The harness remains disconnected from the sensor.
Turn off the keyswitch and the disconnect switch.
At the harness connector for the sensor, measure the voltage from ground contact 2 and frame ground.Expected Result:The resistance is less than 5 ohms.Results:
OK - The resistance is less than 5 ohms. Proceed to Test Step 3.
NOT OK - The resistance is greater than 5 ohms. The harness has failed.Repair: Replace or repair the harness.STOPTest Step 3. CHECK FOR AN OPEN The harness remains disconnected from the sensor.The keyswitch and the disconnect switch remain off.
At the harness connector for the sensor, connect a jumper wire between contact 1 and contact 2.
Disconnect the J1 and J2 harness connectors from the brake ECM.
At the harness connector for the ECM, measure the resistance between contact J1-30 (wire C554-PK) and contact J1-21 (wire J767-GY).Expected Result:The resistance is less than 5 ohms.Results:
OK - The resistance is less than 5 ohms. Proceed to Test Step 4.
NOT OK - The resistance is greater than 5 ohms. The ground circuit has failed.Repair: Repair or replace the harness.STOPTest Step 4. CHECK FOR A SHORTThe switches remain off.The harness remains disconnected from the sensor.The harness remains disconnected from the ECM.
Remove the jumper wire that was installed in the previous step.
At the J1 harness connector for the brake ECM, measure the resistance from signal contact J1-30 (wire C544-PK) to all contacts in the harness connectors for the brake ECM.Expected Result:Each resistance is greater than 5000 ohms.Results:
OK - Each resistance is greater than 5000 ohms. Proceed to Test Step 5.
NOT OK - A resistance is less than 5000 ohms. There is a short between signal contact J1-30 (wire C544-PK) and the circuit with low resistance. Repair: Repair or replace the harness. STOPTest Step 5. CHECK THE SIGNAL AT THE SENSORThe switches remain off.
Reconnect the harness connectors to the brake ECM.
Reconnect the harness to the sensor.
At the harness for the sensor connector, insert a 7X-1710 Multimeter Probe at contacts 1 and 2.
Turn on the disconnect switch and the keyswitch.
Measure the voltage at contacts 1 and 2.Expected Result:The voltage is between