PLATE-CENTER 7F9012 - Caterpillar

Illustration 1 g02936660
Air temperature control circuitThis diagnostic code indicates the brake ECM has determined the air temperature control voltage is below normal.This diagnostic code can be caused by:
Shorted signal circuit
Failed control
Failed power or return circuit
Failed brake 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. INSPECT THE CONTROL PANEL
Visual inspection the following:
Control panel
Control panel wiring
Control panel hardwareExpected Result:The components are in good condition.Results:
OK. - The components are in good condition. Proceed to Test Step 6.
NOT OK. - The components are not in good condition.Repair: Replace the damaged components. Proceed to Test Step 4.Test Step 2. CHECK FOR POWER
Turn on the disconnect switch and the keyswitch.
At the back of the harness connector for the control panel, insert a multimeter probe along contact 1 (voltage supply wire 124-GN).
Measure the voltage from contact 1 (wire 124-GN) to frame ground.Expected Result:The voltage is 24 VDC.Results:
OK - The voltage is 24 VDC. Proceed to Test Step 3.
NOT OK - The voltage is not 24 VDC. The air temperature control power supply circuit has failed.Repair: Check the air temperature control fuse. Replace the fuse if the fuse has failed.If the fuse has not failed, repair or replace the harness.STOPTest Step 3. CHECK THE RETURN CIRCUIT
Turn off the keyswitch and the disconnect switch.
Disconnect the J1 harness connector from the brake ECM.
Remove the multimeter probe from the voltage supply wire (contact 1).
At the back of the harness connector for the control, insert a multimeter probe along contact J1-36 for the sensor signal.
Measure the resistance from contact J1-36 (wire A524-BR) to frame ground.
Measure the resistance from contact J1-36 and all contacts used in the harness connectors for the brake ECM.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 return circuit has failed.Repair: Replace or repair the harness.STOPTest Step 4. CHECK FOR AN OPEN The switches remain off.
Disconnect the harness from the control.
At the harness connector for the control, connect a jumper wire between contact 10 and contact 11.
Disconnect the harness connectors from the brake ECM.
At the harness connector for the ECM, measure the resistance between contact J1-32 (wire 209-BK) and contact J1-36 (wire A524-BR).Expected Result:The resistance is less than 5 ohms.Results:
OK - The resistance is less than 5 ohms. Proceed to Test Step 5.
NOT OK - The resistance is greater than 5 ohms. The harness is open.Repair: Repair or replace the harness.STOPTest Step 5. CHECK FOR A SHORT TO THE +BATTERY CIRCUITThe switches remain off.The control remains disconnected.The harness connectors remain disconnected from the ECM.
Remove the jumper wire that was installed in the previous step.
At the harness connector for the ECM, measure the resistance from the signal contact J1-36 (wire A524-BR) to all contacts in the harness connectors for the ECM.Expected Result:Each resistance is