ALTERNATOR GP-CHARGING 2768899 - Caterpillar

Use the Cat® Electronic Technician (Cat ET) Service Tool or the machine monitors to check for active diagnostic codes. If any diagnostic codes are present, refer to the appropriate diagnostic code troubleshooting procedure to correct this problem before continuing.To check the function of the swing relief valve, perform the following steps:
Verify that main relief is properly set.
Check the swing relief using the procedure in Testing and Adjusting, UENR0445, "Relief Valve (Swing) - Test and Adjust".
If the swing relief low setting cannot be adjusted to the proper setting with the High Pressure Cut Off (HPCO) disabled, verify pump 2 strokes up during the swing command.
The swing relief high setting should not be adjusted. If the swing relief high setting is incorrect, replace the swing relief after verifying that the swing relief is being supplied with pilot pressure using the following procedure.
Shut off the engine by turning the start switch to the "OFF" position. Ground implements and perform the System Pressure Release procedure. Refer to Testing and Adjusting, UENR0445, "System Pressure - Release". Place volt-meter leads on the solenoid that controls the pilot signal to the swing relief valve. Use the long leads to the volt-meter to allow the meter to be monitored from a safe position.
With Hybrid System enabled monitor the voltage being supplied to the swing relief solenoid valve. If the voltage is below 18V, troubleshoot the harness for shorts.
Measure resistance of the swing relief solenoid valve. Resistance should be 32 3.2Ω. If the resistance falls outside of this range, replace the solenoid.
Shut off the engine by turning the start switch to the "OFF" position. Ground implements and perform the System Pressure Release procedure. Refer to Testing and Adjusting, UENR0445, "System Pressure - Release". Plumb a pressure gauge to the pilot line connected to swing relief valve. Use a long hose to monitor the gauge pressure from a safe location.
With the Hybrid System enabled, monitor the pilot pressure sent to the swing relief valve. If pilot pressure does not fall within the specified ranges provided in Testing and Adjusting, UENR0445, "Relief Valve (Swing) - Test and Adjust" use the procedure to adjust pilot pressure.
If pilot pressure was low in step 4.e above, and pilot pressure upstream of the swing relief control solenoid is within specifications, replace the swing relief control solenoid.
Verify the bypasses are functioning by following bypass troubleshooting procedure.
If the bypasses are functioning properly, replace the swing relief valve.