PUMP GP. 7U6875 - Caterpillar

Table 1
Possible Component Root Causes Non-Component Root Causes How to Diagnose Corrective Action
Accumulator Measure the nitrogen pre-charge. IN ET, watch to see which accumulator is cycling rapidly. Follow accumulator charging procedure
Unloader System Failure Unloader tank spikes
Back pressure from high pump command fault Refer to Table 14 in the "Symptom/Fault Code: High Brake Pump Command" Section. Refer to Table 14 in the "Symptom/Fault Code: High Brake Pump Command" Section.
Relay Valve (Front Service Brake) Contamination Check brake system pressure to ensure that pressure upstream of the slack adjustor drops to 0 kPa (0 psi) in less than 1 second with normal operating conditions. If the pressure takes more than 1 second to decay then the valves may not be shifting properly. Service with new kit for the Relay valve (service brakes). Make sure that oil is ISO 18/15 or better.
Relay Valve (Rear Service Brake) Contamination Check brake system pressure to ensure that pressure upstream of the slack adjustor drops to 0 kPa (0 psi) less than 1 second with normal operating conditions. If the pressure takes more than 1 second to decay, then the valves may not be shifting properly. Service with new kit for the Relay valve (service brakes). Make sure that oil is ISO 18/15 or better.
Solenoid valve (Front Automatic Retarder Control) Contamination
Minimum current set too high Check brake system pressure to ensure that pressure upstream of the slack adjustor drops to 0 kPa (0 psi) in less than 1 second with normal operating conditions. If the pressure takes more than 1 second to decay, then the valves may not be shifting properly. Service with new ARC solenoid valve. Make sure that oil is ISO 18/15 or better.
Solenoid valve (Rear Automatic Retarder Control) Contamination
Minimum current set too high Check brake system pressure to ensure that pressure upstream of the slack adjustor drops to 0 kPa (0 psi) in less than 1 second with normal operating conditions. If the pressure takes more than 1 second to decay then the valves may not be shifting properly. Service with new ARC solenoid valve. Make sure that oil is ISO 18/15 or better.
Slack Adjustor N/A Perform residual pressure check. If the residual pressure is higher than specification, then there may be a problem with the slack adjustor. Service Slack adjustor. Make sure that oil is ISO 18/15 or better.
Brake Pedal Valve Contamination
Debris under heal stop of pedal. Measure pedal output pressure. If pressure does not drop to 0 kPa once released pedal may have an issue. Ensure then pedal is clean and free of debris. Service with New Pedal Valve. Make sure that oil is ISO 18/15 or better.
Table 2
Problem: Brake Cooling Temperature Too High (Above 120° C (248° F))
Possible Component Root Causes Non-Component Root Causes How to Diagnose Corrective Action
Unloader System Failure Unloader tank spikes and/or back pressure from high pump command fault Refer to Table 14 in the "Symptom/Fault Code: High Brake Pump Command" Section Refer to Table 14 in the "Symptom/Fault Code: High Brake Pump Command" Section
TCS On/Off