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Ran great, now nothing!
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Author:  coconuteater64 [ Mon May 02, 2011 1:26 pm ]
Post subject:  Ran great, now nothing!
My truck needed some exercise, so off to Lowe's I go. Made a stop before that, ran great. Come out of Lowe's with my purchase.... like it has a dead battery! Checked voltage at the battery, 12.58 volts. Hmmm. Checked it going into the ignition switch, 12.38 volts. Turned on the switch, got 4.5 volts! :x

I tried rolling it down the hill a couple of times, but my titanium/flesh/bone interface did not like that very much. Not enough volts at the coil to crank it I guess. So, what should I look at first? last thing I did was a new voltage regulator about 250 miles ago.
Author:  coconuteater64 [ Mon May 02, 2011 2:46 pm ]
Post subject: 
Update: bypassed the starter switch. Same results; voltage drops to between 4-6 volts. So at least I know it's not in the starter switch. But I had to abandon the effort in order to go to work. :x
Author:  emsvitil [ Mon May 02, 2011 4:40 pm ]
Post subject: 
Sounds like an OLD battery.

Any load and the voltage disappears.........
Author:  4speed [ Mon May 02, 2011 4:48 pm ]
Post subject: 
I agree-it sounds like a bad or flat battery. If you jump start it will it start ok?
Author:  Reed [ Mon May 02, 2011 4:55 pm ]
Post subject: 
Bad batt, possible bad cables.
Author:  WagonsRcool [ Mon May 02, 2011 8:10 pm ]
Post subject: 
I'm a little unclear on where you got 4-6 volts. If you had that going into the ignition switch while you had 12+ V at the battery, then I'd look at the bulkhead connector, starter relay, or battery connections (esp ground side- & eng to body ground) Make sure the battery connections are clean (take 'em apart & scrape 'em down)
Author:  coconuteater64 [ Mon May 02, 2011 8:30 pm ]
Post subject: 
When I hooked the voltmeter to the battery, it was well over 12.5 volts. Same when I measured the volts going into the ignition switch. But when I turn said switch to the run position, the volts drop dramatically to betwen 4-6 volts (tried it a few times). That's also the same voltage going out of the switch. With the switch in the run position, voltage at the battery is still 12V but steady at the switch 4-6 Volts. So I don't think it's the battery, and battery clamps are new. Could a shorted alternator or starter cause something like this?
Author:  4speed [ Mon May 02, 2011 8:46 pm ]
Post subject: 
Are you measuring the voltage on the battery terminal or on the cable clap on it? With the ignition "on" can you measure any voltage from the engine block to the neg term on the battery? Or from the plus term to the bulkhead?
Author:  coconuteater64 [ Mon May 02, 2011 9:07 pm ]
Post subject: 
As measured from battery post itself and battery clamp, same results. Voltmeter + to battery post and voltmeter - to engine block, drops to about 12.3 volts.
Author:  Joshie225 [ Mon May 02, 2011 9:52 pm ]
Post subject: 
You know the big wire coming off the + battery terminal that doesn't go to the starter? Start following that and see where the voltage falls off.
Author:  coconuteater64 [ Tue May 03, 2011 11:21 am ]
Post subject: 
well, duh! I feel so stupid! I forgot a basic lesson is elementary electronics: every wire has two ends!

The battery clamps were the new brass stereo components for the Fast N Furious crowd running 100 gigawatts stereos. But the other end? Yeah, the negative cable looked good on the side I could see, but the bolt into the engine block was rusty, so were the thread holes in the block. A few minutes with a file and a wire whisk and she fired right up first click! I get 14.8 volts at the battery now when running, and 14.3 at the ignition switch (where my aftermarket voltmeter gauge is hooked up). :roll:

Pride versus confidence. Humbling experience.
Author:  4speed [ Tue May 03, 2011 11:56 am ]
Post subject: 
Glad you found it. That is why I asked you "With the ignition "on" can you measure any voltage from the engine block to the neg term on the battery?". That would have shone us the problem. You should not have any voltage to measure that way. If you do its a problem.
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