I am building a track and I only have three out of four lanes working on my track. I was wondering is there someway to use the multimeter that I use to test my arms to test the track and find out what's wrong. If so can somebody tell me how? The track isn't mounted to the table so testing means laying on my back or removing all the track and flipping the table over.

Are each lanes fused? If so I would check your fuse to see if it's blown.

Certainly. You can always use a multimeter on the resistance measurement setting (ohms) or diode test setting (beeps when conductive path exists) to test for conductivity between any two points.

Make sure the power supply is OFF before doing any resistance measurements.

The situation you describe makes me think you have an open circuit somewhere in the electrical path for the affected lane. I always start off with the meter on the diode test scale if the meter has one so it beeps when there is a circuit between the two probes. Otherwise you need to be able to read the meter to see it get near zero ohms. It's simply a matter of finding where there is an open where you should have a connection by walking down the circuit until you find where the break is. It's a "point A is connected to point B, point B is connected to point C, and so on kind of thing." If you have long enough probes or a long jumper you can leave one probe attached to your starting point and then walk the other probe around. This is where the diode test mode beep is handy when you are doing it by yourself.

If you have jumpers soldered to the bottom of your track you'll need to verify that the jumper wire that's going into the hole from below the track is making contact with the rail. To do this you will need to have one probe on the rail and one probe on the wire from below. This may require a long jumper for the probe unless you have very long probe wires.

By jumper wires I mean a length of wire with an alligators clip on both ends. These are indispensable for troubleshooting and other slot car uses, like breaking in brushes using a battery. The last time I was at a Frys I picked up this kit and it has proven to be indispensable. The leads aren't super long (22") but for the occasional times you need longer leads you can daisy chain them together or put a long wire in between two jumpers.

http://shop2.frys.com/product/71920?site=sr:SEARCH:MAIN_RSLT_PG

If you don't have or need a cool set of jumpers you can make probe extensions using whatever wire you have on hand. Use a electrical wire nut to hold the stripped end of the wire to the test probe on your multimeter.