Re: [Amc-list] Battery good - no lights, no horn, no gauges, starter doesn't spin - completely dead electric

[Tom Jennings <tomj@xxxxxxx>]

YOu need a voltmeter, even a cheap one will do. Cheap ones are at least 
5% accurate, that's more than enough. You're looking for changes, not 
precision.

If you got 12V at the battery posts, say, then check "downstream" step 
by step. Assume nothing!

Put the - black voltmeter probe on something convenient, like bare metal 
chassis. Put the red + probe on the battery + post. Should read 12V.

Move the red probe to the other end of the battery cable. Should be the 
SAME as whatever you read on the battery + post directly. If it's more 
than .01V less, bad cable or connection.

You can take this to any extreme. Climb under the dash, check the 
BATTERY post on the igniton switch. Should read (whatever you read at 
the battery + post).

If your car was working, which it's not, you could turn on the tail 
lights, walk to the back of the car, take out a bulb, do the same test, 
and get voltage back there. Same test.

However when the wires are LONG, or the load is HEAVY (like a headlight 
or starter...) the voltage will be LESS when that load is on. This a 
convenient way to test!


GO back to the front of the car. Voltmeter on the battery + and - posts. 
Say to reads 12.5V. Now turn the headlights on. Should drop a BIT, like 
.1V to 1V.

Put the red probe on the solenoid end of the battery cable. Have someone 
turn the car on and CRANK IT. If it doesn't crank, and the voltage stays 
at 12.5V, well, the starter isn't working. On a normal car, it would 
crank and the voltage would DROP to as low as 10, 11 volts. That's 
voltage loss through the cable (and batteries are imperfect).

If the voltage drops to ZERO, or 2, or 8, volts and the car doesnt' 
crank, it's a wiring issue, like bad cables, etc.

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