Inspection Instruments

INSPECTION




1. Sight and sound checks
Check relay operation, blower motor rotation, light illumination, etc. Listen for a "click" when some relay covers are pushed down.




2. Simple checks
For example, if a headlight does not come on and a faulty fuse or poor grounding is suspected, replace the fuse with a new one. Or use a jumper wire to ground the light to the body. Determine which part(s) is/are responsible for the problem.




3. Checking with instruments
Use an appropriate instrument in an adequate range and read the indication correctly.

INSPECTION INSTRUMENTS
For inspection, use the following instruments:

CAUTION: Never use a test light for checking ECU-related circuits or ECUs.




1. Test light
A test light consists of a 12 V bulb and lead wires. It is used to check voltages or short circuits.




2. Self-powered test light
A self-powered test light consists of a bulb, battery and lead wires connected in series. It is used to check continuity or grounding.

CAUTION: Never use a jumper wire to connect a power supply directly to a load.




3. Jumper wire
A jumper wire is used to close an open circuit.




4. Voltmeter
A voltmeter is used to measure the circuit voltage. Normally, the positive (red lead) probe is applied to the point of voltage measurement and the negative (black lead) probe to the body ground. Use a digital voltmeter to check for voltage drop before or after a component.




5. Ohmmeter
An ohmmeter is used to check continuity or measure resistance of a switch or coil. If the measuring range has been changed, the zero point must be adjusted before measurement.