CYLINDER HEAD GP 3643477 - Caterpillar

Test 4
Tapping on the Prelub Mag Switch may temporarily break the weld that is causing the contact disk to stick in the Prelub Mag Switch. Normal operation would be temporarily restored. If this occurs, replace the Prelub Mag Switch. Caterpillar does not recommend this action due to the possibility of breaking the component. Similarly, tapping on the starter solenoid may temporarily break the weld that is causing the contact disk to stick inside the starter solenoid. Normal operation would be temporarily restored. If this occurs, replace the starter solenoid. Caterpillar does not recommend this action due to the possibility of breaking the component.1. Check Harness.
Make sure that the batteries are fully charged and make sure that the batteries are in good condition. Low cranking voltage may contribute to welding of the contact disk.
a. Turn OFF the main disconnect switch.b. Disconnect one of the large wires from the Prelub Mag Switch.c. Turn ON the disconnect switch. Expected Result: The starter motor still runs.
Results:
* Yes - Turn OFF the disconnect switch. The Prelub Mag Switch or the Prelub wiring is shorted. Proceed to 2.* No - Replace the Prelub Mag Switch and retest the system.2. Check Harness.
a. Disconnect the Prelub wire from the motor terminal on the starter solenoid.b. Turn ON the disconnect switch. Expected Result: The starter motor still runs.
Results:
* Yes - The contact disk inside the starter solenoid is stuck. Replace the starter solenoid and retest the system. If the starter motor shows signs of damage replace the starter motor as well.* No - The wiring from the Prelub Mag Switch and the starter motor is shorted. Repair the problems with the circuit and retest the system.Test 5
Do not use "peak hold" or "record mode" on the DMM for this test.1. Check For Excessive Starter Current.
a. Connect a current probe (DC) around either of the large wires that are connected to the Prelub Mag Switch. Use a 9U-5795 Current Probe.b. Turn the key to the CRANK position, and observe the current after the starter motor has run for more than 2 seconds in Prelub Mode. Expected Result: The DMM reads at least 300 amperes while the key is in the CRANK position. The DMM should read at least 400 amperes for 12 volt systems.
Results:
* Yes - The starter current is excessive. Proceed to 2.* No - Service and charge batteries as needed. Check Prelub wiring connections from the starter solenoid to the Prelub Mag Switch for looseness, corrosion, or hot spots. Make sure that the ground connections are good. Repair the problems with the circuit and retest the system. 2. Check For Oil Leakage.
a. Check for oil inside the starter motor. Expected Result: Oil is present inside the starter motor.
Results:
* Yes - This could be accompanied by a Prelub pump lid gasket failure, which is an indication of a Prelub check valve failure or excessive restrictions in the Pressure hose of the Prelub system. Proceed to 3.* No - Replace the starter motor and retest the system.3.