03DelcoRemy Diagnostic Manual130004222020

delcoremy.com Page 19 3-28. TEST COMPLETION. Remove carbon pile and voltmeter. For 12-volt systems, proceed with Alternator Replacement Determination. For 24-volt systems, proceed as follows: 1. Reconnect temporary 12-volt system back to 24-volt system. 2. If Magnetic Switch Circuit Test was delayed, conduct at this time. 3. After completing Magnetic Switch Circuit Test, be sure to reconnect lead to S starter solenoid terminal. Then proceed with Alternator Replacement Determination. NEGATIVE CIRCUIT LOSS (25) CARBON PILE POSITIVE CIRCUIT LOSS (24) DP-1026 FIGURE3-8. AlternatorWiring Test - Typical 12-Volt System 3-29. ALTERNATOR REPLACEMENT DETERMINATION If the alternator wiring circuits are okay, conduct the following tests to determine if the alternator must be replaced. NOTE Make sure that alternator mounting hardware is secure and that belts are OK before testing alternator. NOTE Batteries must be satisfactorily load tested and near full charge with more than 12.4 volts — no load voltage. 3-30. ALTERNATOR VOLTAGE OUTPUT TEST. Conduct this test at shop temperature (See Figure 3-9). Connect 1. Digital voltmeter from positive alternator terminal to alternator ground. Test 1. Start engine and make sure all vehicle electrical loads are turned off. Fast idle engine until voltage stabilizes (does not increase) for two minutes. 2. Check that alternator output voltage does not exceed 15.5 volts (31 volts for 24-volt system). Remove voltmeter. NEGATIVE CIRCUIT LOSS (25) CARBON PILE POSITIVE CIRCUIT LOSS (24) DP-1026 FIGURE3-8. AlternatorWiring Test - Typical 12-Volt System 3-31. ALTERNATOR AMPERAGE OUTPUT TEST. Conduct this test at shop temperature (See Figure3-10). Connect 1. Carbon pile across the vehicle batteries hooked in parallel. 2. Induction ammeter clamped around alternator output wire.