GUIDE-VALVE 4497117 - Caterpillar

Illustration 1 g01253937
Schematic of the bypass pressure switch for the transmission oil filterThis diagnostic trouble code is associated with the bypass pressure switch for the transmission oil filter. The FMI 3 means that the ECU has detected the voltage as being above normal when the engine is not running. The code will change to an FMI16 when the engine is 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.Note: In this application, a transmission a "High Oil Temperature Lamp" may be enabled when this diagnostic code is active.The possible causes of this diagnostic trouble code are listed:
Short to the + battery terminal.
The circuit is open.
A failed switch
The ECU may have failed. The ECU failing is unlikely.Note: The following test procedure may create other diagnostic trouble codes. Ignore these created diagnostic trouble codes and clear these diagnostic trouble codes when the original diagnostic trouble code has been corrected. Ensure that the diagnostic trouble code of SPN 126 FMI 3 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 trouble code.Expected Result:The diagnostic trouble code of SPN 126 FMI 3 is still active.Results:
YES - The diagnostic trouble code is still active. Proceed to 2.
NO - The diagnostic trouble code is no longer active.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