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TROUBLESHOOTING EQUIPMENT
VOLTMETER AND TEST LAMP
Use a test lamp or a voltmeter on circuits without solid-state units and use a test lamp to check for
voltage. A test lamp is made up of a 12-volt light bulb with a pair of leads attached. After grounding
one lead, touch the other lead to various points along the circuit where voltage should be present.
When the bulb goes on, there is voltage at the point being tested.
CAUTION:
A number of circuits include solid-state modules, such as the Engine Control Module (ECM), used
with computer command control injection. Voltage in these circuits should be tested only with a
10-megaohm or higher impedance digital multimeter. Never use a test lamp on circuits that contain
solid state modules. Damage to the modules may result.
A voltmeter can be used in place of a test lamp. While a test lamp shows whether the voltage is
present or not, a voltmeter indicates how much voltage is present.
SELF-POWERED TEST LAMP AND OHMMETER
Use a self-powered test lamp or an ohmmeter to check for continuity. The ohmmeter shows how
much resistance there is between two points along a circuit. Low resistance means good continuity.
CAUTION: Never use a self-powered test lamp on circuits that contain solid state modules.
Damage to these modules may result.
An ohmmeter can be used in place of a self-powered test lamp. The ohmmeter shows how much
resistance there is between two points along a circuit. Low resistance means good continuity.
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