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Illustration 1 | g01416339 |
Power Distribution (1) "B+" main power relay (2) "B+" from ECM breaker (3) Parking brake fuse (4) Reverse alarm fuse (5) Gauge fuse (6) Indicator cluster (7) Backup alarm (8) Backup alarm switch (in propulsion handle) (9) Shift switch (10) Engine ECM (11) Hydraulic oil temperature switch (12) Charge pressure switch (13) Shift valve solenoid (14) Axle pump interlock solenoid (15) Drum pump interlock solenoid (16) Parking brake switch and indicator (17) Brake relay (18) To brake lights (19) Brake relay ("P2") (20) To neutral start relay (21) Neutral start relay ("P4") (22) Neutral start switch (23) From engine start switch in ON or START position |
The 112-PU(Purple) wire distributes power from the main relay to the following fuses: "PARK BRAKE" fuse, "REV ALARM" fuse and "GAUGE" fuse. Power transfers across the "PARK BRAKE" fuse and into the 143-BR(Brown) wire. The 143-BR(Brown) wire delivers power to contact "1" and to contact "3" of the parking brake switch. This wire also transfers power to the contact "30" of neutral start relay "P4" and to contact "2" of the shift switch. Power transfers from the "REVERSE ALARM" fuse to the back up alarm. Power transfers from the "GAUGE" fuse to contact "1" of the indicator cluster.
When the electrical disconnect switch is in the ON position, power is available at the ECM circuit breaker. The 150-RD(Red) wire transfers this power to the following terminals of the engine ECM: terminal "J1-7", terminal "J1-8", terminal "J1-15" and terminal "J1-16".
With the parking brake switch in the ON position, contacts "3" and "4" are closed. Also, power transfers into the 776-YL(Yellow) wire. The 776-YL(Yellow) wire delivers power to the following places:
- Parking brake indicator
- Contact "86" of the brake relay "P1"
- Contact "86" of the brake relay "P2"
- Contact "87" of the brake relay "P2"
When the parking brake switch is in the ON position, the following occurs:
- Parking brake indicator illuminates.
- The coil of brake relay "P1" energizes.
- The coil of brake relay "P2" energizes.
When brake relay "P1" is energized, the axle interlock solenoid and the drum interlock solenoid are de-energized. In this situation, the parking brake is engaged. The parking brake remains engaged when the parking brake switch is in the ON position. This is true regardless of the position of the propulsion lever.
When the propulsion lever is in the NEUTRAL position, power transfers across the neutral start switch and into the 330-YL(Yellow) wire. This wire transfers power to contact "86" of neutral start relay "P3" and to contact "86" of neutral start relay "P4".
When the parking brake switch is moved from the ON position to the OFF position while the propulsion lever is in the NEUTRAL position, the parking brake will release.
With the parking brake switch in the OFF position, contact "1" and contact "2" are closed. In this case, power transfers into the 765-OR(Orange) wire. The 765-OR(Orange) wire transfers power to contact "30" of brake relay "P1".
When the coil of brake relay "P1" is de-energized, contact "30" and contact "87A" of brake relay "P1" are closed. In this case, power transfers to the coil of the axle interlock solenoid and to the coil of the drum interlock solenoid. When the drum interlock solenoid is energized, the parking brake is released.
When the operator moves the propulsion lever out of the NEUTRAL position while the parking brake is in the OFF position, the machine can move.
The parking brake will remain engaged if the parking brake switch is moved from the ON position to the OFF position while the propulsion lever is out of the NEUTRAL position. When the propulsion lever is out of the NEUTRAL position, the neutral start switch is open, and the coil of neutral start relay "P4" is de-energized. Power transfers from the 143-BR(Brown) wire into the 720-PU(Purple) wire across contacts "30" and "87" of neutral start relay "P4". The 720-PU(Purple) wire transfers power to contact "30" of brake relay "P2".
When the parking brake switch is moved from the ON position to the OFF position, contacts "3" and "4" of the switch open. In this case power can no longer be transfered into the 776-YL(Yellow) wire. Usually this would cause the coil in brake relay "P1" and the coil of brake relay "P2" to de-energize, and the parking brake to release. However, since voltage is available at contact "30" of the brake relay "P2", power immediately transfers into the 776-YL(Yellow) wire. In this case, the coil of brake relay "P1" and the coil of brake relay "P2" remain energized. The parking brake indicator will remain illuminated, and the parking brake will remain engaged until the propulsion lever is moved back to the NEUTRAL position.
When the propulsion lever is in the REVERSE position, the back up alarm switch is closed. Under this condition, the ground path for the backup alarm is closed, and the alarm sounds.