When you are working around auto electrical systems, perhaps one of the most important tools you are going to be using when troubleshooting is the fluke digital multimeter.
Your typical digital multimeter will measure current and resistance as well as voltage. But a fluke digital multimeter, however, will take it a step further because it will also measure duty cycle, frequency and dwell. Also known as OHM/volt meter, it's basically the "Swiss knife" of all multimeters because it can also measure temperature, vacuum and pressure as well as make diode tests. Basically, it combines several electronic measurements in one device.
Variety in products
Although these are the basic functions of a fluke, several manufacturers make products that vary in efficiency and accuracy. Of course, there are also products that can vary in terms of application and affordability. There are hand-held devices--which are very convenient because of the mobility--but there are also bigger devices which make it quite heavy for them to be carried around. The are also devices considered as "ultra-smart" which have the capability to graph and log data, make some basic analysis of the results. There are also other meters like the digital clamp meter (which is utilized to compute the filed induced by the current that is flowing through a circuit) or the clamp meter fluke.
Measuring starter current
When the battery is dead, there are many instances when faulty charging is blamed which would necessitate the replacement. But not all starting system problems are due to faulty charging. You have to make sure that the battery passes the load test and charged property before checking the resistance that can be found in the starter circuit.
Using your fluke digital multimeter, you can then check how much the current and resistance the starter is drawing. The multimeter can measure the current up to 1,000 amps then you can check with the manufacturer's specs for the recommended figures. After checking the current, you can then move on to the faulty starter, the insualtion or a tight engine.
Checking the alternator AC
Your alternator will generate voltage and current through electromagnetic induction. It will be responsible for distributing direct current to your car's accessories and make sure they get a steady level of voltage. The problem is you can really charge the battery with alternating current so it must be converted to direct current.
Checking for leakage
In order ot check for alternator diode leakage, you need to connect the output terminal to the fluke digital multimeter but make sure the car is not running. The current you are looking for in leakage is when current jumps a couple of milliamps or around 0.5 millamps. After checking, you can then disconnect the alternator output wire. You can also check the AC voltage or ripple voltage by simply converting your DMM to AC. You must first connect the black lead to the ground and the red lead to the "BAT" terminal on the alternator. In order to know if the alternator is good, it should measure on the multimeter.5 VAC.
