Nissan Sentra manuals

Nissan Sentra Service Manual: Circuit Inspection

DESCRIPTION

NOTE:


NOTE:

Refer to GI-36, "How to Check Terminal" to probe or check terminal.

Testing for “opens” in the circuit

Before you begin to diagnose and test the system, you should rough sketch a schematic of the system. This will help you to logically walk through the diagnosis process. Drawing the sketch will also reinforce your working knowledge of the system.

Before you begin to diagnose and test the system, you should rough sketch a


Before you begin to diagnose and test the system, you should rough sketch a schematic of the system. This will help you to logically walk through the diagnosis process. Drawing the sketch will also reinforce your working knowledge of the system.

Continuity Check Method

The continuity check is used to find an open in the circuit. The digital multimeter (DMM) set on the resistance function will indicate an open circuit as over limit (no beep tone or no ohms symbol). Make sure to always start with the DMM at the highest resistance level.

To help in understanding the diagnosis of open circuits, please refer to the previous schematic.

Any circuit can be diagnosed using the approach in the previous example.

Voltage Check Method

To help in understanding the diagnosis of open circuits please refer to the previous schematic.

In any powered circuit, an open can be found by methodically checking the system for the presence of voltage.

This is done by switching the DMM to the voltage function.

no voltage; open is between fuse block and SW1 (point A).

Any powered circuit can be diagnosed using the approach in the previous example.

Testing for “shorts” in the circuit

To simplify the discussion of shorts in the system, please refer to the following schematic.

Resistance Check Method


Resistance Check Method

Voltage Check Method

Ground inspection

Voltage drop tests


Voltage drop tests

Measuring Voltage Drop — Accumulated Method

Note in the illustration that there is an excessive 4.1 volt drop between the battery and the bulb.

Measuring Voltage Drop — Step-by-Step


Measuring Voltage Drop — Step-by-Step

Control unit circuit test


Control unit circuit test

System Description

When the switch is ON, the control unit lights up the lamp.

CASE 1



CASE 2



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