Charging System: Testing and Inspection
If 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 below:Battery
Charging system indicator
Alternator/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-Check for a blown No.6 (15 A) fuse and a blown charging system indicator light bulb. If the fuse and bulb are OK, repair the WHT/BLU wire or BLK/YEL wire.
2. Start the engine.
Does the charging system indicator go off?
YES-Charging system indicator circuit is OK.
NO-Go to step 3.
3. Turn the ignition switch off.
4. Disconnect the 4P connector from the alternator.
5. 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 step 6.
NO-Repair the open in the BLK/YEL wire between the alternator and driver's under-dash fuse/relay box.
6. Ground the No.3 terminal of the 4P connector.
Does the charging system indicator come on?
YES - Go to step 7.
NO-Turn the ignition switch OFF, and repair the open in the WHT/BLU wire.
7. Disconnect the No.3 terminal of the 4P connector from the ground.
Does the charging system indicator go off?
YES-Test the alternator components.
NO-Turn the ignition switch OFF, and repair short to ground in the WHT/BLU wire.
Alternator and Regulator Circuit Test
1. 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 neutral or park, 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- Repair the voltage regulator.
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 -Test and repair the alternator components.
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 75 A or more?
YES-The charging system is OK.
NO-Go to step 11.
11. With the engine speed still at 2,000 rpm, full-field the alternator. Attach the probe to the VAT-40 full-field test lead, and insert the probe into the full field access hole at the back of the alternator. Switch the field selector to the "A (Ground)" position momentarily, and check the amperage reading. Because voltage will rise quickly when the alternator is full-fielded, do not allow the voltage to exceed 18 V: it may damage the electrical system.
Is the alternator output 75 A or more?
YES-Replace the voltage regulator.
NO-Test and repair the alternator components.
Alternator Control System Test
1. Check proper operation of the ELD by confirming with the MIL.
2. Disconnect the 4P connector from the alternator.
3. Start the engine and turn the headlights (high beam) ON.
4. Measure voltage between the 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 the 32P connector from the ECM/PCM.
7. Check for continuity between the ECM/PCM 32P connector terminal No.19 and body ground.
Is there continuity?
YES-Repair short in the wire between the alternator and ECM/PCM.
NO-Substitute a known-good ECM/PCM, and recheck. If prescribed voltage is now available, replace the original ECM/PCM.
8. Turn the headlight and ignition switch OFF.
9. Disconnect the 32P connector from the ECM/PCM.
10. Check for continuity between the ECM/PCM 32P connector terminal No.19 and alternator 4P connector terminal No.2.
IS there continuity?
YES-Test the alternator/regulator.
NO-Repair open in the wire between the alternator and ECM/PCM.