Alternator Output Test
- With engine at normal operating temperature, remove alternator harness connector. See Fig 1. Turn ignition switch to the "ON" position, then go to next step appropriate to model.
- Battery voltage should be present between "IG" (Black/Yellow) terminal of harness connector and ground. If battery voltage is not present, check No. 14 (10A) fuse in under dash fuse box. Check for open in "IG" (Black/Yellow) wire between dash fuse box and voltage regulator. Replace fuse, or correct or replace wire accordingly.
- If battery voltage is present, turn ignition off. Reconnect alternator harness connector. Connect alternator tester with integral carbon pile (to apply electrical load to system). Start engine. Ensure all accessories are off.
- Operate engine at 2000 RPM and apply a load with carbon pile so voltage reading drops to no less than 12 volts (cooling fan must not come on while testing). Check maximum amperage and compare with appropriate alternator specifications chart in Fig 2.NOTE: Subtract 5-10 amperes from the maximum reading due to engine operation.
- If amperage reading is within specifications, charging system is okay. If amperage is not within specifications, perform a full field test. See FULL FIELD TEST in this article.
- If amperage is still not within specifications after full field test, replace alternator. If full field test is within specifications, go to next step.
- If full field test was correct, check "IG" (Black/Yellow) wire for battery voltage. Battery voltage should exist. If not, repair or replace wire. Check "C" (Yellow/White) wire for a short to ground. If short to ground or faulty signal to ECU exists, or if ECU is faulty, charging system will never charge. If alternator "IG" (Black/Yellow) wire and "C" (Yellow/White) wire is okay, internal voltage regulator is faulty and must be replaced.