Component Tests

Battery

Capacity Testing

To perform this test, use a high rate discharge tester, Rotunda Alternator, Regulator, Battery and Starter Tester (ARBST) 010-00725 or equivalent, in conjunction with Rotunda 73 Digital Multimeter 105-R0051 or equivalent.

1. Turn the control knob on the ARBST to the OFF position.

2. Turn the multimeter selector switch to the DV volt position.

3. Connect ARBST and multimeter positive test leads to the positive battery post and both negative test leads to the negative battery post. The multimeter clips must contact the battery posts and not the ARBST tester clips. Unless this is done, the actual battery terminal voltage will not be indicated.

4. Turn the load control knob in a clockwise direction until the ammeter reads approximately half of the cold cranking amps of the battery.

5. With the ammeter reading the required load for 15 seconds, note the multimeter reading. Avoid leaving the high discharge load on the battery for periods longer than 15 seconds.

6. If the multimeter reading is 9.6 volts at 21°C (70°F) or more, the battery has a good output capacity and will readily accept a charge, if required.

7. If the voltage reading obtained during the capacity test is below 9.6 volts at 21°C (70°F), and the battery is fully charged, the battery is defective and must be replaced. If unsure about the battery's state of charge, charge the battery.

8. After the battery has been charged, repeat the capacity test. If the capacity test battery voltage is still less than 9.6 volts at 21°C (70°F), replace the battery. If the voltage is 9.6 or more at 21°C (70°F), the battery is satisfactory for service.

9. If the battery is found to be discharged only, check for a loose drive belt, loose electrical connection, charging system performance, and perform battery drain testing as described in this section.

Base Voltage Test

NOTE: Prior to running this test, turn the headlamp bulbs (13007) on for 10-15 seconds to remove any surface charge from the battery. Then, wait until the voltage stabilizes before performing the base voltage test.

1. With the ignition off and no electrical loads on, connect the negative (-) lead of Rotunda 73 Digital Multimeter 105-R0051, or equivalent, to the battery ground cable (14301) clamp.

2. Connect the positive (+) lead of the voltmeter to the battery to starter relay cable (14300) clamp.

3. Read and record the battery voltage shown on the voltmeter. This is called base voltage and will be used in later tests.

No-Load Test

1. Connect Rotunda 88 Digital Multimeter 105-R0053 or equivalent to monitor engine speed.

2. Connect the leads of Rotunda 73 Digital Multimeter 105-R0051 or equivalent across the battery terminals.

3. Read the voltage (base voltage).

4. Start the engine (6007).

5. Run the engine at 1500 rpm with no electrical load.

6. Read the voltage. The voltage should be in the range of 14.1 to 14.7 volts. If the voltage increase is less than 2.5 volts over the base voltage, perform the following Load Test. If there is no voltage increase or the voltage increase is greater than 2.5 volts, perform the Generator On-Vehicle Tests and Generator Bench Tests in the Diagnosis and Testing portion of this section.

Load Test

1. With the engine running, turn the air conditioner on, if equipped, the blower motor (18527) on high speed and the headlamps on high beam.

2. Increase the engine speed to approximately 2000 rpm. The voltage should increase a minimum of 0.5 volts above the base voltage. If the voltage does not increase as specified, refer to Generator On-Vehicle Tests and Generator Bench Tests in the Diagnosis and Testing portion of this section.

   If the voltage increased as specified, the charging system is operating normally. Proceed to the following battery tests.

Field Circuit Drain

Alternate Test Method

Use Rotunda Power Sensor Plus Electronic Battery Test 162-00002. Follow the manufacturer's defined test procedure.

Drain Testing

Check for current drains on the battery in excess of 50 mA with all the electrical accessories off and the vehicle at rest. Current drains can be tested with the following procedure.

 WARNING: DO NOT ATTEMPT THIS TEST ON A LEAD-ACID BATTERY THAT HAS RECENTLY BEEN RECHARGED.

 CAUTION: Do not crank the engine or operate accessories that draw more than 10A. You could blow the fuse in the meter.

NOTE: Many computers draw 10 mA or more continuously.

NOTE: Use Rotunda 88 Multimeter 105-R0053 or equivalent between the battery positive or negative post and its respective cable.

1. NOTE: Steps 1-5 correspond to the numbers in the following illustration.

   Insert the test leads in the input terminals shown.

2. Turn switch to mA/A DC.

3. Disconnect battery terminal and touch probes as shown.

4. Isolate circuit causing current drain by pulling out one fuse after another while reading the display.

5. Current reading will drop when the fuse on the bad circuit is pulled.

6. Reinstall fuse and test components (including connectors) of that circuit to find defective component(s).

   
   
   
   
   

Typically, a drain of approximately one amp can be attributed to an engine compartment lamp, glove compartment lamp, or luggage compartment lamp staying on continually. Other component failures or wiring shorts may be located by selectively pulling fuses or disconnecting fuse links to pinpoint the location of the current drain. When the current drain is found, the test lamp will go out or the meter reading will fall to an acceptable level. If the short is still not located, after checking all the fuses and fuse links, the drain may be due to the generator.

Test Conclusion

The current reading (current drain) should be less than 0.05 amps. If it exceeds 0.05 amps it indicates a constant current drain which could cause a discharged battery. Possible sources of current drain are vehicle lamps (underhood, glove compartment, luggage compartment, etc.) that do not shut off properly.

If the drain is not caused by a vehicle lamp, remove the fuses from the interior fuse junction panel, one at a time, until the cause of the drain is located. If drain is still undetermined, remove fuses one at a time at the main fuse junction panel to find the problem circuit.

Electronic Drains Which Shut Off When the Battery Cable Is Disconnected

1. Repeat Steps 1 through 6 of the voltmeter drain testing.

2. Without starting engine, turn ignition on for a moment and then off. If applicable, wait one minute for the illuminated entry lamps to turn off.

3. Connect the voltmeter and read the voltage.

Test Conclusion

The current reading (current drain) should be less than 0.05 amps. If it exceeds 0.05 amps after a few minutes, and if this drain did not show in previous tests, the drain is most likely caused by a malfunctioning electronic component. As in previous tests, remove the fuses in interior fuse junction panel one at a time to locate the problem circuit.

Generator On-Vehicle Tests

Troubleshooting or diagnosis is required before actual service can be made in the electrical system. Even where an obvious condition makes replacement of a component necessary, find out why the component failed. When a condition is diagnosed correctly, unnecessary service is prevented, the time the vehicle is out of service will be decreased, and the condition will be properly corrected the first time.

In order to check the charging system, the use of Rotunda Alternator, Regulator, Battery and Starter Tester (ARBST) 010-00725 or equivalent tester is suggested.

When performing charging system tests, turn off all lamps and electrical components. Place transmission in neutral and apply parking brake.

 CAUTION: Do not make jumper wire connections except as directed. To do so may damage generator (GEN) (10346).

 CAUTION: Do not allow any metal object to come in contact with the housing and internal diode cooling fins with key on or off or short circuit will result and burn out diodes.

NOTE: Battery posts and cable clamps must be clean and tight to ensure accurate meter indications.

Load Test

1. Switch the Rotunda Alternator, Regulator, Battery and Starter Tester (ARBST) 010-00725 or equivalent to the ammeter function.

2. Connect the positive and negative leads of the Rotunda Alternator, Regulator, Battery and Starter Tester (ARBST) 010-00725 or equivalent to the battery (10655).

3. Connect the current probe to the generator B+ output lead, Circuit 38 (BK/O). On Mitsubishi 215 ampere generator, use Circuit 605R.

4. With the engine running at 2000 rpm, adjust the Rotunda Alternator, Regulator, Battery and Starter Tester (ARBST) 010-00725 or equivalent load bank to determine the output of the generator. Generator output should be greater than the graph shown below. If not, refer to the Symptom Chart in the Diagnosis and Testing portion of this section for diagnostic procedures.

   
   
   
   
   
   
   
   
   

No-Load Test

1. Switch the Rotunda Alternator, Regulator, Battery and Starter Tester (ARBST) 010-00725 or equivalent to the voltmeter function.

2. Connect the voltmeter positive lead to the generator B+ terminal and the negative lead to ground.

3. Turn all electrical accessories off.

4. With the engine running at 2000 rpm, check the generator output voltage. The voltage should be between 13.0 and 15.0 volts. If not, refer to the Symptom Chart in this section for diagnostic procedures.

Generator Bench Tests (Integral Rear Mount Regulator, Internal Fan Generator)

NOTE: The integral rear mount regulator — internal fan type generator (GEN) (10300) is serviced as an assembly only.

Replace generator as required after performing generator on-vehicle tests. Refer to Section 14-02B.

Capacitor

The radio voltage regulator capacitor (18832) connected across the heat sinks may be tested on a capacitor tester if available. Its value is .158 MFD, and 100 working volts DC.

In the absence of a capacitor tester, the unit may be checked for shorts by means of an ohmmeter connected across the terminals. A reading under 20 milli-ohms indicates a shorted or leaking radio voltage regulator capacitor which should be replaced.