SEAL 7X7720 - Caterpillar

Illustration 1 g00315182
Schematic of the Temperature Sender (Hydraulic Oil)
This diagnostic code is recorded when the main display module reads the signal from the sender and the signal is too high. The possible causes are listed below:
The sender has failed.
The signal circuit in the machine harness is shorted to the + battery.
The main display module has failed.Note: Very low resistance in the sender causes the main display module to read the signal wire as having voltage too low. Low resistance can be caused by a short to ground in the signal circuit. This would cause the corresponding gauge on the display to indicate an abnormally high value. Very high resistance in the sender causes the main display module to read the signal wire as having voltage too high. High resistance can be caused by an open in the signal circuit. The internal circuitry of the main display module would pull a high voltage in the signal wire. This condition is recognized as a gauge that always has an indicator at the far left side of the scale.Service Notes: Ensure that the desired diagnostic code is on hold. Ensure that the fault present indicator shows "SERV CODE". The schematic that is shown above represents a typical installation of the component. Verify the connector contact and wire numbers by using the Electrical System Schematic for the machine that is being serviced. Test Step 1. CHECK THE MAIN DISPLAY MODULE AND THE HARNESS.
Turn the disconnect switch and the key start switch to the ON position.
The diagnostic code indicator should show "SERV CODE".
Disconnect the machine harness from the sender that is causing the problem.
Observe the diagnostic code indicator. Expected Result:The diagnostic code indicator is ON.Results:
YES - The diagnostic code indicator stays ON. The harness wiring or the main display module has failed. Proceed to test step 2.
NO - The diagnostic code indicator turns OFF. The sender has failed.Repair: Replace the sender.STOPTest Step 2. CHECK FOR AN OPEN GROUND.
Turn the disconnect switch and the key start switch to the OFF position.
Measure the resistance between frame ground and the ground wire for the sender. Expected Result:The resistance is 5 ohms or less.Results:
YES - The resistance is 5 ohms or less. Proceed to test step 3.
NO - The resistance is greater than 5 ohms. The ground wire for the harness is open.Repair: Repair the ground wire or replace the ground wire for the sender.STOPTest Step 3. CHECK THE SIGNAL WIRE FOR THE SENDER.
The machine harness remains disconnected from the sender.
The disconnect switch and the key start switch remain in the ON position.
At the machine harness connector for the sender, measure the voltage. Measure the voltage between the frame ground and the signal wire (442-GY(Grey)). Expected Result:The voltage that is measured is within one of the following specifications.Results:
6.0 0.5 DCV - The voltage is 6.0 0.5 DCV. The voltage is correct. Verify that the diagnostic code is still present. Repair: It is unlikely that the main display module has failed. Exit this procedure and perform this