2002/08/19 Correction to Operation and Maintenance Manual , "Caterpillar Monitoring System" {7451, 7490} Caterpillar

Off-Highway Truck/Tractor:

776D (S/N: AFS1-UP)

777D (S/N: AGC1-UP)

777D HAA (S/N: AGY1-UP)

Operation and Maintenance Manual, SEBU7261, "776D Tractor and 777D Off-Highway Truck", "AVSpare Monitoring System". This module is part of Service Manual, RENR3330.Operation and Maintenance Manual, SEBU7268, "777D HAA Off-Highway Truck", "AVSpare Monitoring System". This module is part of Service Manual, RENR3330.

Disregard the information for "Brake On (15)" in the "Alert Indicators" section. Disregard the information for "Brake On (33)" in the "Warning Category 1" section. Disregard the information for "Brake On (43)" in the "Warning Category 3" section. Refer to the following information.

Alert Indicators

Brake On (15) - This alert indicator will be on when any one of the three following conditions exists:

• The parking brake is engaged.

• One of the brake master cylinders has a brake overstroke condition.

• The parking brake is disengaged and the system air pressure is below the requirements for your machine.

Warning Categories

Warning Category 1

Brake On (33) - This alert indicator will be on when the parking brake is engaged and the transmission is in NEUTRAL.

This alert indicator should come on during start-up. If the alert indicator continues to flash after releasing the parking brake, you must determine the cause of the warning before you place the transmission in gear.

Note: The brake system air pressure must be above 550 kPa (80 psi) in order to release the parking brake.

Warning Category 3

Brake On (43) - This alert indicator will be on when any one of the three following conditions exists:

• The transmission is not in NEUTRAL and the parking brake is engaged.

• One of the brake master cylinders has a brake overstroke condition.

• The parking brake is disengaged and the system air pressure is below the requirements for your machine.

If this alert indicator comes on during operation and the transmission is in gear, be sure that the parking brake is released.

Note: The brake system air pressure must be above 550 kPa (80 psi) in order to release the parking brake.

If the alert indicator does not go out after releasing the parking brake, one of the following conditions exists:

• a brake overstroke condition

• low system air pressure

Immediately stop the machine in a safe manner. Do not operate the machine until the reason for this Category 3 warning is corrected.

When pistons in the master cylinders travel too far, a brake overstroke condition is the result. This can be caused by one of the following conditions:

• low brake fluid level

• air in the brake hydraulic circuit

• leakage in the brake hydraulic lines

• master cylinder piston seal leak

Air pressure for the secondary brake system may be low for a brief time after engine start-up. Always allow the air tanks for the brake system to recharge before you operate your machine.