The breaker tests 118v with the wire disconnected. I connect the wire and the voltage drops to 2.4v. I tried a new breaker and the same thing happens. What is causing this?

it appears the power supply is faulty, as with a high electrical resistance in line with the load. My guess is carbon build.
Power supplies or sources have internal resistance and can not deliver more amperes than rated at. In your case there would be a resistance that allows you to read voltage with no load connected, actualy the only load would be your voltage meter, 10 mega ohms per volt? Try using a solenoid type voltage dsetector and you'd get no volts detected, because there is a high resistance either in the wiring or power source.
Trouble shoot: disconnect the wiring from the power source, short out the wires at the load, with the load disconnected, read ohms on the wires or conductor where they were disconnected from the source, it should be close to a few ohms but not high ohms, if your wires check out ok, then go to the power supply, is there a circuit breaker or electric connection offering high ohmage to the circuit? A load can be connected here to the source, a head lamp or something hungry for power but don't exceed or overload the power source.
Yes, this is about voltage drop in series with the load, loosing all your voltage in a high resistance in line with the circuit, not across the line but in line, in series.

Could be a bad battery cable or connection ! If it clicks it must be getting some voltage . A voltage drop test of the starting circuit would be the thing to do . Starter Voltage Drop buy yourself a volt meter . How to voltage drop test starter motor circuit . Find wiring diagrams for your vehicle , not all car makers do it the same way . http://www.bbbind.com/free_tsb.html free wiring diagrams . Watch videos on basic automotive electrical testing , how to read a wiring diagram . Then test the electrical circuit of the starter system .

Here are links to help, then add a comment:
http://waterheatertimer.org/images/Inside-Main-Breaker-Box-12.jpg
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http://waterheatertimer.org/See-inside-main-breaker-box.html
http://waterheatertimer.org/Color-codewire.html
http://waterheatertimer.org/How-to-wire-T104-Intermatic-timer.html#T104
http://waterheatertimer.org/images/Test-wires-for-voltage-1-600.jpg
http://waterheatertimer.org/images/T104-wire-from-breaker-600.jpg
Always stand on dry boards and never directly on ground when testing live electricity. Do no lean into or touch anything made of metal. Tape wood sticks to tester leads.
240Volt circuit does not use neutral wire. Neutral is used to complete circuit for 120Volt... and that is only function for neutral.
Neutral and ground wires connect back to same wire coming in from the electric company transformer. So in a sense, neutral and ground are same.
However both neutral and ground wires connect to separate busbars inside the breaker box. And then both those busbars are bonded together or joined together ... so ground and neutral become the same thing inside breaker box.
For national electric code, the ground wire runs to each fixture, outlet, motor, appliance etc. The ground wire is essential for safety.
Absolutely the ground wire must connect to motor in case the motor housing becomes electrified after the motor overheats etc.
The ground wire carries no voltage and is safe to touch ... but don't test that theory in event there is funky off-code wiring on premises.
Please add a comment May 2013 for followup, and if you need specific wiring diagram... attach image of your situation

If you need further help, I’m available over the phone at https://www.6ya.com/expert/gene_9f0ef4df2f9897e7

Please reply with Model number of bottom of AC unit ( upper) . Can be seen from inside usually. Thermostat model, plus if controls are at the ceiling assy or at thermostat on wall.

Turn off power between each action listed below.

Is dial rotating and keeping time on timer?
This will tell you if 120V is arriving and working at timer.
Cut ground wire and check circuit again.
This can narrow down ground fault problem.
Disconnect wires from timer and connect wires direct to outdoor lights.
This will tell you if timer is suspect.

List all things on same circuit breaker, and test each to find which are working.
Each electrical box is connected to next box and to next box back to circuit breaker.
Open each box and check for loose wires, signs of burning.
This will narrow down location of problem.

When working in main breaker box, the wires on main breaker have power at all times, even when main breaker is turned off. This is true unless meter is pulled. Always stand on dry boards and never lean into or touch anything else when working in main box. Do not hold screwdriver between teeth.
Tape tester leads to wood sticks to keep hands away from voltage.
Test voltage at circuit breaker. Make sure neutral and ground are attached tight on busbar. Make sure black wire is attached tight to breaker. Move black wire to another same-size circuit breaker. Disconnect ground wire and test circuit again to check if ground fault is causing problem.

Resources and illustrations.
http://waterheatertimer.org/See-inside-main-breaker-box.html
http://waterheatertimer.org/How-to-replace-circuit-breaker.html
http://waterheatertimer.org/B220C.html

The first thing to look at would be the fuse. The fuse must be in the main fuse box. The position and function of the fuses is normally marked on the inside of the fuse box cover and also in the owner's handbook. If you don't come right with these, work your way through the fuses looking for a blown one. To ease your search the pump fuse it should be around 30 amps.

You did not say what the amp draw was nor what the amp rating on the pump motor was. Also you need to have the running volts tested to see if there is a voltage drop.

I suggest you hook up 12 V digital multitester to the battery running & get your voltage. Next stop the truck & get the voltage leaving it connected & you should see the voltage steadily dropping. Then, take off the Negative cable & hook up the tester again to the 2 post of the battery & see if the voltage drops as before, or has stabilized. That will tell you if the truck is draining the battery for sure of if you have a bad cell. If it is the truck, you will need to go through troubleshooting the entire vehicle by eliiminating all use of current and gradually hooking things back up. IE: disconnect main fuses/breakers & see what happens on the tester. Then start connecting 1 item at a time & see what is requiring power or if you have a short. You should eventually find the culprit even if you have to remove fuses and test each time. An additional tester that test amperes without penetrating the wiring is helpful in finding the drain. Normally in the auto-parts stores. I just lay mine over the wiring & follow the voltage until I find the wiring leading to the one using the power or that is shorted. Good Luck.

4 wire recepticals are used for 220 Volt appliances, there should be 2 hot (117V to ground) and one each Grounding and grounded (read neutral) conductors) Breaker or disconnect should be 2 pole for 220 Volt circuit. A 20 Amp 110/117 Volt circuit would have a single pole breaker or disconnect, one "hot" conductor(should be black or colored , not green or white), one neutral conductor (should be white or neutral with white stripe) and an equipment grounding conductor (should be green or bare copper). It sounds to me like your receptical was wired for 220 V using whatever colored wires were handy. Back up to breaker or fuse (disconnect), and shut off circuit. New 117 Volt outlet will be wired with Black to Brass colored screw (short slot on face), One White wire will be used for Neutral conductor (make sure you know which one it is at the breaker panel) and one of the other white wires may (but shouldent be) used for ground (use green marker to identify it at each end),The third white wire should be removed if you can, otherwise cap with wire nut at each end and coil up in back of boxes. At the breaker/ fuse panel, the Black wire is connected to the breaker (It will be your "hot" lead), The white being used for the Neutral is connected to the neutral buss bar with the other Neutrals, and the green goes to the grounding buss bar (should have other green or bare copper wires. Once all is properly connected and secured but without the disposal plugged in, turn on the power and check for leaking smoke (smoke here is a bad thing) The fuse or breaker should protect your wires and help keep that smoke inside the boxes. Check voltages at the new plug, 117 V accross Short and longer slot, 117 from short to ground (round) and 0 or close to it from long (Neutral) to ground. If voltages check, plug in the new appliance and test.
If in doubt about what you have, dont hesitate to contact an electrician, they get paid for their knowledge and experiance and their ability to keep that nasty smoke inside the boxes.
Good Luck.,

There is loose connection somewhere.Might want to look at the wires coming to the panel.