545 Wheel Skidder Power Train Caterpillar

The components for the starting system are the key start switch, the relay control, the transmission direction switch, the start relay, the starter, and the fuel shutoff solenoid.

Illustration 1	g00708657
Schematic for the Key Start Switch (1) Key start switch. (2) Relay control. (3) Transmission direction switch.

Note: The transmission direction control switch is located in the steering wheel.

Note: The relay control is mounted underneath the fuse box.

Relay control (2) activates the start relay when the following conditions are met.

• Key start switch (1) is in the Start position.

• The transmission direction switch is in the NEUTRAL position.

The start relay energizes the starter.

The starting motor cranks but the engine will not start. Check the fuel shutoff solenoid for a malfunction.

There are two possible malfunctions of the starting system that could be caused by the circuitry of the relay control.

• The starting motor does not crank.

• The starting motor cranks whenever the transmission is in neutral.

The same procedure for key start switch (1) checks either malfunction.

Check the key start switch.

1. Turn the battery disconnect switch to the OFF position.

2. Disconnect relay control (2) from the machine harness. Turn the battery disconnect switch to the ON position. Turn and hold key start switch (1) in the START position. At the machine harness connector for relay control (2), measure the voltage between contact 1 (wire 307-OR) and contact 2 (wire 202-BK).
   • Positive battery source is present. Proceed to Step 3.

   • Positive battery source is NOT present. Check for a blown fuse for the key start switch. The key start switch or the machine harness (wire 307-OR) is faulty. Check the key start switch and the machine harness. If necessary, replace the key start switch and/or the machine harness.

3. The relay control remains disconnected from the machine harness. Turn the key start switch to the OFF position. At the machine harness connector for relay control (2), measure the voltage between contact 1 (wire 307-OR) and contact 2 (wire 202-BK).
   • Positive battery source is present. The key start switch or the machine harness (wire 307-OR) is faulty. Check the key start switch and the machine harness. If necessary, replace the key start switch and/or the machine harness. STOP

   • Positive battery source is NOT present. The harness circuit operates correctly. It is unlikely that relay control (2) is faulty. Perform these Steps again. If the cause is not found, replace relay control (2).