If you ever wondered what eles you can do with your volt meter I found this articile while looking for something else; you can use your voltmeter to test your engine coolant.
http://www.cadillacforums.com/forums/cadillac-forum/t-60843.html

mcowden
12-22-05, 01:47 AM
Antifreeze Analysis

In stead of using a coolant test strip:
“You can also use an ordinary digital volt meter for the same purpose. With the engine off, touch the voltmeter positive test lead to the radiator or engine (making sure you get good metal-to-metal contact). Then open the radiator cap and insert the negative test lead into the coolant. A reading of up to 0.2 volts is considered acceptable and indicates the presence of reserve alkalinity in the coolant. If the coolant reads 0.3 to 0.6 volts, it is borderline and should be recycled or replaced. A reading of 0.7 volts or more would tell you the coolant is overdue for a change.
Internal corrosion in the cooling system can occur regardless of the condition of the coolant if voltage from various accessories (alternator, starter, ignition, etc.) flows through the coolant to ground rather than follows the intended ground path through the ground strap between the engine and chassis or the ground cable between the engine and battery. You can check for this condition by also using your DVOM. Use the same hookups as before to measure the voltage of the coolant, but this time while cranking the engine, then with the engine running and lights and heater on. If stray current is grounding through the coolant, you'll get a voltage reading. More than 0.15 volts can corrode aluminum, and 0.3 volts can be harmful to cast iron. Check, clean and tighten the ground straps and/or battery ground connection to eliminate the problem.”

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84 300D, 82 Volvo 244Gl Diesel