GUARD AS 1246042 - Caterpillar

Illustration 1 g01943976
Connections of the bypass pressure switch for the transmission oil filterThis diagnostic code is associated with the bypass pressure switch for the transmission oil filter. The FMI 03 means that the ECU has detected the voltage as being above normal when the engine is not running. The bypass switch is a normally open switch. The switch will become closed when the switch is installed. The switch will then become open when the filter is plugged and the oil needs to bypass the filter in order for the transmission to receive oil.The possible causes of this diagnostic code are listed:
Short to the + battery terminal.
The circuit is open.
A failed switch
The ECU may have failed. This is unlikely.Note: The following test procedure may create other diagnostic codes. Ignore these created diagnostic codes and clear these diagnostic codes when the original diagnostic code has been corrected. Ensure that the diagnostic code of CID 0126 FMI 03 is active before performing this procedure.Note: Use a digital multimeter for the measurements in this procedure.Test Step 1. CHECK FOR AN OPEN CIRCUIT.
Turn the disconnect switch and the key start switch to the ON position.
Disconnect the harness from the switch.
Connect a jumper wire to pin 1 and pin 2 of the harness.
Observe the status of the diagnostic code.Expected Result:The diagnostic code of CID 0126 FMI 03 is still active.Results:
YES - The diagnostic code is still active. Proceed to 2.
NO - The diagnostic code is no longer active. Proceed to 3.Test Step 2. CHECK FOR A SHORT CIRCUIT TO POSITIVE VOLTAGE.
The disconnect switch remains in the OFF position.
Disconnect the harness from the ECU.
At the J1 machine harness connector, measure the resistance from contact J1-63 and contact J1-21 to all other J1 and J2 contacts and to all possible sources of positive voltage.Expected Result:The resistance measurement is greater than 5000 ohms for each measurement.Results:
OK - The resistance measurement is greater than 5000 ohms for each measurement. The circuit is correct. Proceed to Test Step 4.
NOT OK - The resistance measurement is not greater than 5000 ohms for one or more measurements. A short exists in the circuit.Repair: The short is in the circuit with the low resistance measurement. Repair the harness or replace the harness. Verify that the problem has been corrected.STOPTest Step 3. CHECK THE SWITCH FOR PROPER OPERATION.
Disconnect the switch and remove the switch from the vehicle.
Replace the switch with a new switch.
Observe the status of the diagnostic code.Expected Result:The switch is operating correctly and the diagnostic code is not active.Results:
YES - The diagnostic code is not active. The new switch has corrected the problem. The original switch was faulty.STOP
NO - The diagnostic code is active. The new switch has not corrected the problem. Proceed to Test Step 4.Test Step 4. CHECK IF THE DIAGNOSTIC CODE IS STILL ACTIVE.
Inspect the harness connectors. Clean the contacts of the harness connectors and check the wires for damage to the insulation that is caused by excessive heat, battery acid, or chafing.
Perform a 45 N (10 lb) pull