Nissan Teana J32. Manual - part 634
GI-40
< BASIC INSPECTION >
SERVICE INFORMATION FOR ELECTRICAL INCIDENT
• For detailed ground distribution information, refer to “Ground Distribution” in PG section.
VOLTAGE DROP TESTS
• Voltage drop tests are often used to find components or circuits which have excessive resistance. A voltage
drop in a circuit is caused by a resistance when the circuit is in operation.
• Check the wire in the illustration. When measuring resistance with DMM, contact by a single strand of wire
will give reading of 0 ohms. This would indicate a good circuit. When the circuit operates, this single strand
of wire is not able to carry the current. The single strand will have a high resistance to the current. This will
be picked up as a slight voltage drop.
• Unwanted resistance can be caused by many situations as follows:
- Undersized wiring (single strand example)
- Corrosion on switch contacts
- Loose wire connections or splices.
• If repairs are needed always use wire that is of the same or larger gauge.
Measuring Voltage Drop — Accumulated Method
• Connect the DMM across the connector or part of the circuit you want to check. The positive lead of the
DMM should be closer to power and the negative lead closer to ground.
• Operate the circuit.
• The DMM will indicate how many volts are being used to “push” current through that part of the circuit.
Note in the illustration that there is an excessive 4.1 volt drop between the battery and the bulb.
Measuring Voltage Drop — Steb-by-Step
• The step-by-step method is most useful for isolating excessive drops in low voltage systems (such as those
in “Computer Controlled Systems”).
• Circuits in the “Computer Controlled System” operate on very low amperage.
SGI853
SGI974