Hi everyone, Randy here again. I guess I'm not screwing up as bad as I thought because those magazine editors keep asking me to write another column. They said as long as I have something to talk about I can keep writing the column.
Well, I came out of the Crab Shack the other day and saw a parking cop putting a ticket on a car. I ran up and said, "C'mon, how about a break?" Cop kept writing the ticket. I said, "Dang cops writing tickets for the meter just expiring; should get a real job." Cop finished the first ticket and started another one for a broken taillight. I said, "Sheesh, next you are going to write a ticket for the cracked windshield." Sure enough, the cop finished the taillight ticket and wrote a windshield ticket, then got in her little golf cart and left. I really don't like meters or meter maids, but don't worry, it wasn't my car anyway.
I'm here to talk about a different kind of meter this month-a multimeter. A multimeter is a very useful tool to have with you in your Jeep for when something goes wrong. You can test your alternator, your battery, circuits, fuses, and all kinds of things with one.
The problem is, people get confused on how to use a multimeter, and that's where I'm hoping to help. First off, for a meter to keep in the Jeep, don't go getting the $300 unit that does inductive amperage and all kinds of fancy stuff. For most problems, a cheapie one like this one from RadioShack will do just fine.
The second thing that many people do is, they go and get a meter that has a dial and a bunch of numbers. That gets confusing real fast.
You need to remember three things when getting a multimeter: You want a digital one, you want it to be "auto-ranging," and you want auto-shutoff so you don't kill the batteries.
It should cost you about 20 bucks, and once you end up needing it, you will thank me.
Once you have the multimeter, or multitester, or volt-ohm meter (call it what you want), you will mainly only use two functions: volts (V or I) or ohms (O). If it is in the Jeep and wired up, test it for voltage. If it is out of the Jeep, test it for ohms. That's basically it.
This is a good lightbulb. It didn't work in the Jeep, so I pulled it, put the multimeter in the ohms range, and tested it. If the meter returns a number, it is good. If it's all zeros, "err," or "out of range," it means the lightbulb is bad. This holds true for many items in the Jeep, especially fuses, circuit breakers, and fusible links. | 
This is the first test I do with every Jeep I play with. I look to see how many volts the battery has. This one is good with 12.44. Usually, the Jeep will start all the way down in the 10V range. Sometimes a battery will show good voltage, but won't crank the Jeep. That is usually due to one or more bad cells and it's usually time to replace the battery. If the Jeep is running and the alternator is good, you should see 14.4 or so volts here. |
The next step in chasing down a light that doesn't work, if the bulb is good, is to test the socket. The middle of the socket is positive, the outside is negative. As you can see by the all-zeros while in the volt range, there is no power here. If there should be power, next is to try and figure out where the power gets lost. | 
The next step is to use the continuity feature. Some meters have this as a separate symbol , and in some it is integrated into the ohm measuring feature. By putting one end of the meter in the fuse block at the fuse for that circuit, and then testing the wire and connections from one end to the other, you can find where the break in the wire is. When there is continuity, it means that the circuit is continuous or unbroken. |