ALTERNATOR GP-CHARGING 1501935 - Caterpillar

Introduction
On the pages that follow is a list of possible problems. Several common problems are covered but these problems are not arranged in any particular sequence.Before checking the list of problems, check the ECM display for any diagnostic codes that may be shown. These codes will aid in finding the problem (see Diagnostic Code Interpretation).Identify your particular type of problem from the Problem List, then go directly to that problem. However, when you begin the procedure for that problem, start at Step 1 and follow through the step by step procedure. The steps in a particular problem provide a definite sequence to be followed for a logical, one by one elimination of many variables. These steps are arranged in order from the more probable/easiest to check, to the less probable/more complex to check.When the cause of the problem is found and corrected, stop the test. Do not continue through the complete procedure just because it is there.
Do not connect generator to a utility electrical distribution system, unless it is isolated from the system. Electrical feedback into the distribution system can occur and could cause personal injury or death.Open and secure main distribution system switch or, if the connection is permanent, install a double throw transfer switch to prevent electrical feedback. Some generators are specifically approved by a utility to run in parallel with the distribution system and isolation may not be required. Always check with your utility as to the applicable circumstances.
When servicing or repairing electric power generation equipment, do the following:a. Make sure the unit is off-line (disconnected from utility power service and/or other generators), and either locked out or tagged "DO NOT OPERATE".b. Make sure the generator engine is stopped.c. Make sure all batteries are disconnected.d. Make sure all capacitors are discharged.When power generation equipment must be in operation to make tests and/or adjustments, high voltage and current are present. Make sure the testing equipment is designed for and correctly operated for the high voltage and current tests being made. Improper test equipment may fail and present a high voltage shock hazard to its user.
When the engine-generator, or any source to which the engine-generator may synchronize to, is operating, voltages up to 600V are present in the control panel.Do not short these terminals with line voltage to ground with any part of the body or any conductive material. Loss of life or injury could result from electrical shock or injury from molten metal.
Test Instruments
Caterpillar Digital Multimeter (6V7070) - can be used for many of the voltage and resistance checks. Rectifiers can also be checked with the special diode function. For further information on using the digital multimeter, see Special Instruction, Form SEHS7734. See the following if generator is rated over 600 volts.
On generators with higher than 600 volts rating, do not used direct-reading test equipment to measure the voltage or line current, (even though the instrument has higher voltage capacity). Voltage and current transformers with a high voltage reading must be used. On power circuits higher