No not the battery's voltage you want to use a volt o meter thing on the wire that goes to the O2 sensor. If you have an FSM it should cover how to do this test in there. It should have what the voltages should be at in the book.
As for the vac leak test I would pressure test and listen for leaks. The spraying carb cleaner around the running motor test sucks. Especially if your motor is having problems running.
Basically all you do is pull the MAF and the air filter and cap off the intake pipe with a coupler and a PVC pipe cap. Clamp the cap on nice and tight. Then if you have an air compressor find a hose or un used nipple on the intake manifold and run that to the compressor. Pressurize the system to about 15psi or and turn off the compressor and listen and feel for leaks.
If you don't have an air compressor you can use a bicycle pump, or you can modify a hand pump plant sprayer
As for the vac leak test I would pressure test and listen for leaks. The spraying carb cleaner around the running motor test sucks. Especially if your motor is having problems running.
Basically all you do is pull the MAF and the air filter and cap off the intake pipe with a coupler and a PVC pipe cap. Clamp the cap on nice and tight. Then if you have an air compressor find a hose or un used nipple on the intake manifold and run that to the compressor. Pressurize the system to about 15psi or and turn off the compressor and listen and feel for leaks.
If you don't have an air compressor you can use a bicycle pump, or you can modify a hand pump plant sprayer