Preliminary Checks

Before performing charging or starting system tests on the vehicle, note the complaint such as: slow cranking, battery discharged or using an excessive amount of water, top of battery wet, generator warning lamp does not come on or never goes out. This information will aid in isolating the part of the system causing the symptom.

Next, visually inspect as follows:

1. Check the fuse link located between the starter solenoid and the generator. Replace the fuse link if burned.

2. Make certain that the battery is OK; then turn on the headlamps or any other accessory. If the headlamps or accessory do not operate, the fuse link is probably burned out.

3. On some vehicles there are several fuse links. Use the same procedure as in Step 1 to test the fuse link that protects vehicle equipment.

   To test the fuse link that protects the generator, make certain the battery is OK. Then check with a voltmeter for voltage at the BAT terminal of the generator. No voltage indicates that the fuse link is probably burned out.

4. Check battery posts and battery cable terminals for clean and tight connections. Remove the battery cables (if corroded), clean and install them securely.

5. Check for clean and tight wiring connections at the generator, voltage regulator and engine ground.

6. Check the generator belt tension. Refer to Section 03-05.
   • When a relatively new battery is discharged, test for current drain. Refer to Section 14-01 for proper procedures. The following are some of the most common current drain problems:
     • Glove compartment lamp stays on with the door closed
     • Hood lamp stays on constantly
     • License plate lamp or interior lamp stays on constantly
     • Other electronic component malfunctions
   • Check for secure ground connections at the engine and body. Also check for proper connections at the generator and voltage regulator.
   • Check the testing equipment and instructions. If the equipment is malfunctioning or the instructions for use are incorrect, use the equipment on a vehicle you know to be operating properly.
   • Only test the charging system with a fully charged, properly operating battery. Make sure cable connections are clean and secure.

   In order to check the charging system, the use of Rotunda Starting/Charging VAT-40 Tester 078-00005 or equivalent is suggested. Connect the tester to the battery positive and negative posts and also connect the current probe to the generator + output lead (to measure generator output). (When measuring generator output, the tester can also be connected to the battery positive or negative cable. In this case, all electrical accessories must be turned off and 10-15 amps added to the reading on the tester due to the engine operation). With the engine running at 2000 rpm, adjust the tester load bank to determine the output of the generator. The generator output should be near to, or exceed the generator rating (27°C (80°F) ambient). Checkout the charging system as indicated and service if required.

   NOTE: Refer to the tester test procedure manual for complete directions on checking out the charging system.