Alternator Output Test
- Remove alternator connector. Turn ignition switch to "ON" position. There should be battery voltage between "IGN" (Black/Yellow) terminal and ground.
- There should also be battery voltage between "B" (White wire) terminal and body ground. If no voltage is present, go to next step. If voltage is present, go to step 5).
- Check for a blown No. 4 fuse or an open in Black/Yellow wire between dash fuse box and voltage regulator.
- Connect voltmeter positive lead to positive battery terminal and negative lead to alternator "C" connector (Blue wire). Start engine and turn all accessories off. If battery voltage is present, go to next step. If no voltage is present, check for an open in Blue wire between voltage regulator and Electronic Control Unit (ECU).
- Test system using an alternator tester with an integral carbon pile. Operate engine at 2000 RPM and ensure cooling fan is off. Apply a load with carbon pile so voltage drops to no less than 12 volts. Check maximum amperage and compare with specifications on chart. See Fig 1.NOTE: Subtract 5-10 amperes from maximum reading for engine operation.
- If amperage is within specification, charging system is okay. If amperage is not within specification, perform a full field test. Full field test can be performed with charging system tester, or by grounding regulator with metal probe through full field access hole in rear housing. See Fig 2.
- If amperage is still not within specification, alternator is defective. If amperage is within specification, replace voltage regulator.