PISTON 5597585 - Caterpillar

Check for loose or corroded terminals. Make sure wire connections are correct. Check the accuracy of the voltmeter and frequency meter/tachometer.To reduce troubleshooting time, simplify the system or circuit by eliminating non-essential components such as remote voltage control, manual control, etc. If, at this point, it is determined that the basic system is functioning, the circuits or components can be added back in, one at a time until the problem is located.If elimination of non-essential components does not correct the problem, the troubleshooting procedure will check components in the basic system. If all other basic components (i.e. rotating field assembly, exciter stator, etc.) are operating correctly, then replace the VR3F regulator. As a last step after confirming correct operation under no load conditions, operate the generator under a load.The VR3F regulator is serviced as a complete unit. The regulator fuses are the only replaceable part. VR3F regulators must be checked through the bench test before making a claim on warranty (see Bench Test).
Do not operate the generator with sensing leads 20, 22 and 24 disconnected or with the fuses removed. To do so will result in high unstable generator output voltage.