WASHER 9W7388 - Caterpillar

All Caterpillar Machines With AlternatorsReference: Special Instruction, SEHS7633, "Battery Test Procedure".Reference: Service Magazine; May 28, 1990; "Testing The Starter On The Engine".Reference: Service Magazine; July 7, 1986; "Brushless Alternators May Not Charge In Certain Conditions".Reference: Service Magazine; January 19, 1987; "Difference Between Alternator Indicator In Electronic Monitoring System (EMS) And Low Voltage Indicator In Operating Monitoring System (OMS)".Often when problems with the charging system are being investigated, the alternator is not the problem. If a low battery condition is present, test the batteries first. See Special Instruction SEHS7633 "Battery Test Procedure" for more information. If the engine cranks slowly, then test the starting system. See Service Magazine SEPD0020 "Testing The Starter On The Engine" for more information. If a warning indicator for the charging system is ON, see Service Magazine SEBD1751 "Difference Between Alternator Indicator In Electronic Monitoring System (EMS) And Low Voltage Indicator In Operating Monitoring System". When a problem with the charging system is suspected, then complete the testing that is outlined in this article.
See "Initial Troubleshooting Procedure" in order to begin troubleshooting. The procedures in this article are designed to guide you to the problem with as little testing as possible. In most cases, you will only use a few of the tests to diagnose a problem. The tests are labelled as T1 - T8 for easy reference. A descriptive title for each test is included as well.
Initial Troubleshooting Procedure
1. CHECK THE RESISTANCE IN EXCITATION CIRCUIT. This step is only for alternators with external excitation when the terminal for excitation is labelled "1", "REG", or "D+". See "Alternator Specifications" if the method of excitation is unknown. Go to Step 3 if your alternator is self-excited. Go to Step 2 if your alternators terminal for excitation is labelled "IG".a. Turn the key start switch to the ON position.b. Verify voltage at the excitation terminal. Connect the red lead from a multimeter to the excitation terminal. Connect the black lead to a ground source (such as the alternator case).c. Read the voltage that is shown on the multimeter. Expected Result: The voltage reads at least .2 volts.
Results:
* YES - The voltage reads .2 volts or more. The excitation circuit is correct. Proceed to Step 3. * NO - The voltage is less than .2 volts. There is a fault in the wiring harness to the alternator or there is a poor electrical connection. Correct the problem and operate the machine. Watch for a recurrence of the problem. 2. CHECK THE RESISTANCE IN EXCITATION CIRCUIT (CONTINUED). This step is only for alternators with external excitation when the terminal for excitation is labelled "IG". See "Alternator Specifications" if the method of excitation is unknown. Go to Step 3 if your alternator is self-excited. a. Turn the key start switch to the ON position. b. Verify voltage at the excitation terminal. Connect the red lead from a multimeter to the excitation terminal. Connect the black lead to a ground source (such as the alternator case).
Special Wire Probing Technique