Alternator and Regulator Circuit Test
Alternator and Regulator Circuit lest1. Be sure the battery is sufficiently charged.
2. Connect a VAT-40 (or equivalent tester), and turn the selector switch to position 1 (starting).
3. Shift to Park or Neutral, and start the engine. Hold the engine at 3,000 rpm, with no load until the radiator fan comes on, then let it idle.
4. Raise the engine speed to 2,000 rpm, and hold it there.
Is there voltage over 15.1 V?
YES - Repair the alternator.
NO - Go to step 5.
5. Release the accelerator pedal, and let the engine idle.
6. Make sure all accessories are turned off. Turn the selector switch to position 2 (charging).
7. Remove the inductive pick-up, and zero the ammeter.
8. Place the inductive pick-up over the B terminal wire of the alternator so that the arrow points away from the alternator.
9. Raise the engine speed to 2,000 rpm, and hold it there.
Is there voltage less than 13.5 V?
YES - Go to Alternator Control System Test.
NO - Go to step 10.
10. Apply a load with the VAT-40 until the battery voltage drops to between 12 - 13.5 V.
Is the amperage 87.5 A or more?
YES - The charging system is OK.
NO - Repair the alternator.
Alternator Control System Test
1. Check for proper operation of the ELD by checking the MIL.
2. Disconnect the alternator 4P connector from the alternator.
3. Start the engine, and turn the headlights (high beam) ON.
4. Measure voltage between the alternator 4P connector terminal No. 2 and the positive terminal of the battery.
Is there 1 V or less?
YES - Go to step 8.
NO - Go to step 5.
5. Turn the headlight and ignition switch OFF.
6. Disconnect PCM connector C (31 P).
7. Check for continuity between the PCM connector terminal C2 and body ground.
Is there continuity?
YES - Repair short in the wire between the alternator and PCM.
NO - Substitute a known-good PCM and recheck. If prescribed voltage is now available, replace the original PCM.
8. Turn the headlight and ignition switch OFF.
9. Disconnect PCM connector C (31 P).
10. Check for continuity between the PCM connector terminal C2 and alternator 4P connector terminal No. 2.
Is there continuity?
YES - Repair the alternator.
NO - Repair open in the wire between the alternator and PCM.