G3B, K3A and L3A Denso Alternators Caterpillar

T8 Alternator Overcharging - Test

Usage:

426C 1CR

Clean and tighten the connection to the wiring terminal on the alternator.

Verify that the alternator B+ terminal nut is tight and verify that the wire has a good connection to the B+ terminal.

Many Caterpillar machines are equipped with a connector for the 6V-2150 Starting/Charging Analyzer . Use of this analyzer replaces the testing below through Step 8. Therefore, if the testing is good, go to directly to Step 9. If the analyzer finds a problem, correct the problem and retest the system. Go to Testing and Adjusting, "Initial Troubleshooting Procedure" .

Start the engine and set the throttle at 75 percent. Turn ON all electrical accessories for all test steps below. Allow the engine to run for at least 3 minutes before continuing to Step 5. The following table will assist in making calculations during this test.

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Table 1
Test Step	Voltage Reading	Voltage should be below this for 12 volt system	Voltage should be below this for 24 volt system
5
6
5 minus 6 =		1.0 volt	2.0 volts
7
8
7 minus 8 =		0.5 volt	1.0 volt

Measure the voltage between the alternator B+ terminal and the alternator case ground.

Measure the voltage across the battery. Put the red lead on the positive battery terminal, and put the black lead on the negative battery terminal. Step 6 should be completed as quickly as possible after Step 5 .
Expected Result: On 12 volt systems, the voltage is within one volt of the voltage recorded in Step 5. On 24 volt systems, the voltage is within 2 volts.
Results:
- YES - If the voltage in Step 5 is not more than 1 volt for 12 volt systems (2 volts for 24 volt systems) higher than the voltage in Step 6, this step is complete and the related wiring is correct at this time. Go to Step 9 .
- NO - If the voltage in Step 5 is more than 1 volt for 12 volt systems (2 volts for 24 volt systems) higher than the voltage in Step 6, there is high circuit resistance: corrosion, loose connections and damaged wiring. Go to Step 7.

Check the voltage between the machine frame and the alternator B+ terminal. Record the voltage.

Check the voltage between the machine frame and the positive battery post. Step 8 should be completed as quickly as possible after Step 7.
Expected Result: The voltage difference between Step 7 and Step 8 does not exceed 1 volt on 24 volt systems or 0.5 volts on 12 volt systems.
Results:
- YES - The voltage difference does not exceed the tolerance. The charging circuit is good. Go to Step 9 .
- NO - The voltage difference exceeds the tolerance. There is high resistance in the charging circuit: loose cables, corroded cables, damaged cables, faulty circuit breaker and faulty main relay. Correct the problem. Go to Testing and Adjusting, "Initial Troubleshooting Procedure" retest the system.

Start the engine and set the throttle to at least 75%. Turn all accessories OFF.

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Illustration 1	g00496660

Insert a 7X-1710 Multimeter Probe Group into the rear of the middle wire in the connector. See figure 1. Insert the probe (spoon lead) between the black seal that surrounds the wire and the outer shell of the connector. Do not insert the probe between the wire insulation and the black seal. This terminal (IG) is the terminal for excitation.

Measure voltage between IG terminal and alternator case.
Expected Result: The voltage (at the IG terminal) is above specification.
Results:
- YES - The voltage is over specification. The alternator or regulator is faulty. Replace the alternator or go to Testing and Adjusting, "Component - Test" .
- NO - The voltage is below that found in the initial tests (B+ to alternator case). The sense circuit in the machine has high resistance. Correct the problem and restest the system. Go to Testing and Adjusting, "Initial Troubleshooting Procedure" .