PIN-SPRING 2L3650 - Caterpillar

System Operation Description:Use the diagnostic flow chart as a reference, while you are troubleshooting the alternator charging system.
Illustration 1 g00706351
Diagnostic flow chartNote: Severely discharged batteries can cause a low system voltage. This condition can occur even when the alternator is working properly. This condition can also occur while the engine is running above idle. Proper low engine idle is important. Alternator output can be low at idle.Note: The alternator is self-excited. Self-excited alternators must exceed a turn-on speed before charging will begin.Test Step 1. CHECK THE SYSTEM VOLTAGE.
Before you start the machine, connect a voltmeter between the "B+" terminal and the case of the alternator. Turn OFF all electrical loads.
Turn the key to the ON position but do not start the engine. Read the voltage on the voltmeter. Make a note of the voltage that was measured.Expected Result:This voltage should be approximately system voltage. Results:
YES - The voltage is approximately system voltage. Proceed to test step 2.
NO - The voltage is less than system voltage. Proceed to test step 4.Test Step 2. CHECK THE OPERATION OF THE ALTERNATOR.Note: For the proper output voltage, refer to Specification, "Alternator".
The voltmeter remains connected between the "B+" terminal and the case of the alternator.
Start the machine. Set the throttle to at least 75 percent. Read the voltage on the voltmeter. Make a note of the voltage that was measured.Expected Result:The voltage measurement is greater than the voltage that was recorded in the previous test step "Check The System Voltage".Results:
VOLTAGE HIGHER - The voltage measurement is greater than the voltage that was observed in the previous test step "Check The System Voltage". The voltage is also less than the maximum voltage that is listed in the specifications for the alternator. The alternator is partially charging the battery. Proceed to test step 3.
VOLTAGE TOO HIGH - The voltage measurement is greater than the voltage that was observed in the previous test step "Check The System Voltage". The voltage is also greater than the maximum voltage that is listed in the specifications for the alternator. The alternator is over charging. Proceed to test step 16.
VOLTAGE LOWER - The voltage is not higher than the voltage that was observed in the previous test step. Proceed to test step 4.Test Step 3. TEST THE ALTERNATOR OUTPUT.Note: For the proper output current, refer to Specification, "Alternator".
Ensure that the batteries are NOT fully charged.Note: A fully charged battery may have open circuit voltage above 12.5 V on 12 V systems. 24 V systems may be as high as 25 V.
If the batteries are fully charged, then crank the engine for 30 seconds. This action reduces the battery voltage. Operate the lights for 10 minutes while the engine is off as an alternative.
Connect the 9U-5795 Current Probe to a DMM (digital multimeter) or use a 225-8266 Ammeter Tool Gp . The multimeter must have a peak hold feature. Clamp the probe around the alternator output wire "B+". Before you clamp the probe around the wire, ensure that the probe is "zeroed".
Set