Sort your electrics with the following tests.

Equipment: digital multimeter, for most tests set in DC Volts 0-20V range
(if not auto-ranging)


When measuring voltage on a good wire from one given point to another, the good wire will conduct all the voltage
leaving little to be measured. The gold standard for this sort of test is about .2V loss. With a measurement less than that
you can be certain that the wire is good, and well connected. More that .2V, suspect corrosion, frays, loose connections
or some other form of bad wiring.

.2 Volts = 200 milivolts




Alternator to Solenoid
(often uses as a buss for fuse box and for unfused accessories, too) Use a digital multimeter selected to volts. If not auto-ranging, choose 20vdc scale.

Put red lead on the solenoid, black lead on alternator. Should read less than .2 v
If not, clean and/or replace wire.

Battery to solenoid.

Same meter setting, measure from red post on battery to battery post of solenoid. Pull coil power wire. Crank for a couple seconds. Again, if meter shows greater than .2 volts, bad connection or wire.

Charge voltage at battery

Connect red lead to red post of battery, black to neg post
turn all accessories off
start engine, idle
meter should read 13.2 - 14.5 vdc
if less, alternator is not putting out correct voltage, slipping belt, loose connection

Alternator charge, loaded


Connect leads to battery -- red to plus, black to neg

Start car, let idle

Read voltage as in last test

Turn on lights

Voltage should be same plus/minus .2volts

If voltage drops more than .5 volts, rev engine to 1500rpm and hold steady

If voltage increases to no-load reading, alternator is OK

If not, check connections, belt etc.

Turn meter function to AC volts. Should read less than .5 volt AC -- if over, bad alternator (alternator diodes leaking)

Ground test

Meter to DC volts 0-20 range

Red lead to alternator body, not terminal (fin, nut, etc.)

Black lead to a body, not engine, ground point

Start engine

Turn on lights

If meter shows more than (you guessed it) .2 vdc, you have a ground strap problem