Charging System: Testing and Inspection
Charging Circuit TroubleshootingIf the charging system indicator does not come on or does not go off, or the battery is dead or low, test the following items in the order listed:
Battery
Charging system indicator
Alternator and regulator circuit
Alternator control system
Charging System Indicator Test
1. Turn the ignition switch ON (II).
Does the charging system indicator come on?
YES - Go to step 2.
NO - Go to step 6.
2. Start the engine.
Does the charging system indicator go off?
YES - Charging system indicator circuit is OK. Go to the Alternator and Regulator Circuit Test.
NO - Go to step 3.
3. Turn the ignition switch OFF.
4. Disconnect the alternator 4P connector from the alternator.
5. Turn the ignition switch ON (II).
Does the charging system indicator come on?
YES - Turn the ignition switch OFF, and repair the short in the WHT/BLU wire.
NO - Go to step 9.
6. Turn the ignition switch OFF.
7. Disconnect the alternator 4P connector from the alternator.
8. Connect the alternator 4P connector terminal No. 3 to body ground with a jumper wire. Turn the ignition switch ON (II).
Does the charging system indicator come on?
YES - Go to step 9.
NO - Turn the ignition switch OFF. Check for a blown No. 6 (15 A) fuse and a blown charging system light bulb. If the fuse and bulb are OK, repair the open in the BLK/YEL or WHT/BLU wire.
9. Measure the voltage at the No. 1 terminal of the alternator 4P connector with the ignition switch ON (II).
Is there battery voltage?
YES - Go to the Alternator and Regulator Circuit Test.
NO - Repair open in the BLK/YEL wire between the alternator and the driver's under-dash fuse relay box.
Alternator and Regulator Circuit Test
1. Be sure the battery connections are good, and that the battery is sufficiently charged and in good condition.
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 the voltage over 15.1 V?
YES - Replace the rear housing assembly.
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 the 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 or replace the alternator.
Alternator Control System Test
1. Check for proper operation of the electrical load detector (ELD) by checking the malfunction indicator lamp (MIL). If a DTC is present, diagnose and repair the cause before continuing with this test.
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 powertrain control module (PCM) connector C (31P).
7. Check for continuity between the PCM connector C terminal No. 2 and body ground.
Is there continuity?
YES - Repair short to ground 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 (31P).
10. Check for continuity between the PCM connector C terminal No. 2 and alternator 4P connector terminal No. 2.
Is there continuity?
YES - Repair or replace the alternator.
NO - Repair open in the wire between the alternator and PCM.