ELECTRICAL SYSTEM CONTINUED
The start relay is located in the fuse panel enclosure. This enclosure is located under the left console over the left
The ECM must detect that the following input information is correct before energizing the start relay.
The FNR position sensor must indicate thatthe direction handle is in the NEUTRAL position
The parking brake switch must be in the ON position
The key switch must be in the START position
When the ECM detects that the machine systems input information is correct, it will send a +battery signal to the
coil of the start relay in order to energize the relay. This will cause the secondary contacts of the relay to close. This
will send +battery power from the main buss to the start motor solenoid.
The ECM monitors the circuit for the start relay. If it determines that an abnormal condition exists in the circuit, the
ECM will log a diagnostic code.
The backup alarm is an output of the ECM. The backup alarm alerts nearby personnel that the machine is backing
up. When the FNR position sensor indicates that the direction handle is in the REVERSE position, the ECM will
activate the output for the backup alarm.
Magnet (Blade Float)
The blade float magnet detent coil is mounted internally on the front side of the bulldozer attachment control handle
When the key switch is in the ON position, the float solenoid is energized unless the hydraulic lockout switch is in
the LOCKED position. When the control handle is moved to the full blade down position (full forward), the magnetic
force that is created by the energized coil will hold the handle in the forward position. When this occurs, the
hydraulic flow to the cylinders will be blocked and both ends of the cylinders will be open to the tank.
Figure 20. Blade Float.