How to Test for Voltage - Click HERE

How to Test for Resistance - Click HERE

Things to Look Out For - Click HERE

Note: This has been prepared as a guide only.  If you would like to offer any constructive criticism to improve the article - please feel free to contact me by clicking here...

Digital Multimeters

Analog Multimeter

The multimeters above are different types, the yellow one is

the most popular one, the center black one is a car

multimeter. It can read RPM, injector pulse, AC temperature,

etc. The one on the right is  also very common and is the

cheapest one to buy.

Multimeters measure AC and DC voltages, car batteries supply

DC voltage, while wall outlets in your home supply AC voltage.

Digital meters will give you a digital display; analog meters

will use a needle or a pointer on a calibrated scale. Some ranges

won't have their scales, so you may need to read a scale for

 another range and then multiply or divide the reading

This meter is set on 20 volts; you can see the scale ranges from 200mm

"millivolts" to 100 volts DC.  The AC volts is the scale below and ranges

from 2 volts to 700v.  The small green plug-in on the right is for

 measuring Temp. For example - for the A/C output on you car you

would put the sensor near the vent and read the

Meter. You need a special adapter for this function.

How to Test For Voltage

Measuring the Voltage of a Car Battery

- Select AC or DC, we are going to select DC for the car "normally 12 volts" this is all the voltages on your vehicle.

- Set the meter for the proper range in a car you should be in the 10 to 20 volt range.

- Some meters have auto-range, which means it will set the range it self.

- If your testing your car battery. Touch the red lead to the + terminal of the battery and the black to the - terminal of the battery.  You should get anywhere from 10v to 14v, depending on the condition of the battery.  (At this point the car is not running.)  If the car was running you would get a higher reading, provided your alternator is charging, then your volts will be higher, 12v to maybe 14.7 or so!

- When testing for voltage make sure the black lead is on a good ground "Chassis".

- You can even use the battery ground if you're in the engine compartment.

- In the case when checking for volts you can even use a test light.

How to Test For Resistance

Zeroing the Meter

Resistance Measured in a Wire

- Resistance is measured in ohms, or sometimes called "continuity".

- Set your meter to the ohms scale lowest setting.

- Make sure the power to the wire you are testing in this test is off, damage to the meter is sure to occur if "Voltage" is put through the meter.

- Now ZERO the meter, that means you will touch the two leads together.

- You will get a 0.00 reading or close. This means that a small amount of current is going from one lead to the other, if the "wire" or lead was broken you would not get a reading.

- You may need to adjust the thumbwheel  in the OHM scale to get a 0.00 reading.

- Now you can test for a broken wire or a short to ground, or even a spark plug wire, burnt fuse, light bulb, or a switch, or even circuit breakers.

 Resistance tells us how much a circuit will resist the flow of electric current.

These are different sensors you can use with the multimeter. The left and center ones plug into the

multimeter and are used to measure temperature; the one on the right is used with an

Automotive Multimeter to read the engine's RPM's.

Things to Look Out For

- Make sure your meter is set to the right scale, for volts or Ohms.

- If checking volts set to higher scale than car voltage.  Example - Car is 12v set meter for next higher scale 20v.

- On the Ohms scale I don’t worry to much about the scale, unless you are measuring the specific resistance of a component.

  i.e. Resistor or some spark plug wire manufacturers specify a resistance for their wires.  The longer the wire, the more resistance.

- Always turn your meter off after use, some turn off on their own.  (Most have an OFF switch.) 

  They all have batteries in them and if left ON, the OHM scale they will drain the batteries!