Short Circuits; Voltage - Ford Ranger Maintaince And Repair Manual

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The infinite reading on this multimeter indicates that the circuit is open

This test already assumes the existence of an open in the circuit and it is used to help locate the open portion.

Isolate the circuit from power and ground.

Connect the self−powered test light or ohmmeter ground clip to the ground side of the circuit and

probe sections of the circuit sequentially.

If the light is out or there is infinite resistance, the open is between the probe and the circuit ground.

If the light is on or the meter shows continuity, the open is between the probe and the end of the

circuit toward the power source.

SHORT CIRCUITS

Never use a self−powered test light to perform checks for opens or shorts when power is applied to the

circuit under test. The test light can be damaged by outside power.

Isolate the circuit from power and ground.

Connect the self−powered test light or ohmmeter ground clip to a good ground and probe any

easy−to−reach point in the circuit.

If the light comes on or there is continuity, there is a short somewhere in the circuit.

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).

Leave the test light probe engaged and sequentially open connectors or switches, remove parts, etc.

until the light goes out or continuity is broken.

When the light goes out, the short is between the last two circuit components which were opened.

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.

Set the voltmeter selector switch to the 20V position.

HOW TO USE THIS BOOK

OPEN CIRCUITS

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