Voltage Drop; Low Voltage Measurement - Chevrolet Trailblazer Service Manual

2. Connect the self-powered test light or ohmmeter ground clip to a good ground and
probe any easy-to-reach point in the circuit.
3. If the light comes on or there is continuity, there is a short somewhere in the circuit.
4. To isolate the short, probe a test point at either end of the isolated circuit (the light
should be on or the meter should indicate continuity).
5. Leave the test light probe engaged and sequentially open connectors or switches,
remove parts, etc. until the light goes out or continuity is broken.
6. When the light goes out, the short is between the last two circuit components which
were opened.
Voltage
This test determines voltage available from the battery and should be the first step in any
electrical troubleshooting procedure after visual inspection. Many electrical problems,
especially on computer controlled systems, can be caused by a low state of charge in the
battery. Excessive corrosion at the battery cable terminals can cause poor contact that will
prevent proper charging and full battery current flow.
1. Set the voltmeter selector switch to the 20V position.
2. Connect the multimeter negative lead to the battery's negative (–) post or terminal
and the positive lead to the battery's positive (+) post or terminal.
3. Turn the ignition switch ON to provide a load.
4. A well charged battery should register over 12 volts. If the meter reads below 11.5
volts, the battery power may be insufficient to operate the electrical system
properly.

Voltage Drop

Low voltage measurement