defective switches, or accessories. This condition of discharge leads to a frequently rundown battery and starting failure complaints. Turn the vehicle ignition switch to OFF. Lights and accessories must be OFF and doors closed. Observe the AMMETER scale. If the ammeter scale reads zero, there are no short or grounded circuit paths for current, in which case the electrical system is okay and all tests are completed. If the ammeter scale reads other than zero, an electrical short or grounded circuit exists if all the vehicle circuits are turned OFF. The short or grounded circuit may be found by isolating each circuit, one at a time, until the ammeter reads zero. The last circuit isolated, as the ammeter returned to zero, is the defective one. Many circuits can be isolated by removing the circuit & from the fuse panel.
When you finish the test, shut the engine down and turn the ignition switch to the OFF position before disconnecting any test leads.
Reconnect the ground cable to the ground post of the battery, and make sure all vehicle wires disconnected during the testing are again securely and properly connected.
Normally, when an engine analyzer (fig. 4-15) is available for use, it is in the electrical shop. The following information explains how to use the analyzer to test alternators. In considering this information, remember the following points: (1) the example shown is one of several manufactured, (2) the analyzer will do much more than just test alternators, and (3) ALWAYS refer to the manufacturer's manual of the analyzer and the unit being tested before making any connections.
Figure 4-15.-Engine analyzer.Continue Reading