( I hate electrical problems. It's the one area of a vehicle's engine that I yell "Uncle!" to )


I own a Ford Ranger with a 2.9 six cylinder engine with 212,000 miles on it and a six month old battery to start things off.

The current problem revealed itself about two weeks ago when I went to start it one morning and it just didn't have enough juice to engage the starter. All I got was that dreadful clicking sound. I thought the battery had just died because I had not driven it in three days, and the morning was unusually cold. A friend told me that a good battery, particularly a relatively new one like mine, should start a vehicle with a two week layover. True ?

Against my better judgement, I took it to a local Mobil station nearby to have it checked out and their mechanic told me that I needed a new alternator. Given the truck is 16 years old, and I had never replaced the alternator, I took his word for it and told him to go ahead and replace it if it solved the problem.

Well, in the last few days, it has become painfully obvious that starting it had become more and more laborous, as it seemed to barely have enough juice to crank it over. This morning, I went to start it and my worst fears were realized when it not only would not start, but even the dome light and hood light weren't working.
After finding someone to jump it, I took it back to the mechanic who sold me the alternator and he threw in a new battery from his stock to test it, and claimed that it was the battery, or possibly a short somewhere.
I took it back to where I bought the battery ( Autozone ), and after bringing out some huge contraption to diagnose it, he said the battery was fine, and that it was the regulator inside this new alternator that was at the root of the problem with an outside chance of a short somewhere. I've decided to take a long drive tomorrow to an electrical shop that has always done good work with all of my vehicles, and at very reasonable prices, so here are my questions:

1.) I know from 28 years of car owning experience that batteries can occasionally leave the factory with a bad cell or two, but wouldn't a bad cell reveal itself almost immediately ?

2.) Can alternators, or their embodied regulators, leave the factory bad ? Could the regulator have been shorted when being installed or is that at all that common ?

3.) What exactly is a "short" ?

Thank you in advance.

Palani

 

Well I think I can answer # 3 for you. A electrical "short" is when
electrical current takes a unplaned path.Such as when the + bat post
gets against the fender.The current takes a shorter path by
bypassing the intended load and going directly to - ground. I believe a "short" on the alternator output
could damage the regulator.To check the alternator it schould be putting out around 13.8 volts.Except a heavy load
"like a dead battery" can pull the voltage down until it is partially recharged.You will probably get a better answer than this but I hope this helps.


Larry

 

Thank you, Larry. I just noticed that I posted these queries under the wrong topic heading...I can't do anything right todat. Sheesh.

Palani

 

something is draining the battery overnight. follow all the wiring to like power locks or windows or lights. my neibur had a similar problem with a pontiac van. turned out his power locks had a short and drained the battery. go figure

 

 

[updated:LAST EDITED ON 02-Apr-02 AT 11:31 PM (EST)]Hi Palani.

Go to the left side of my reply and see the word *Gallery*
click that!
Now look at all the links I have to different things>
One of them is "Finding a short in an electrical system".
click that >
Go grab a coffee or beer and have a good read.

You could probably fix the problem yourself.


[i][font color=blue]Dennis[/font][i]

[font color=red]Calgary,Alberta,Canada[/font]
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64-Fairlane500 S/C waiting for a 390-4spd.
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>something is draining the battery overnight. follow all the
>wiring to like power locks or windows or lights. my neibur
>had a similar problem with a pontiac van. turned out his
>power locks had a short and drained the battery. go figure


It is fairly easy to tell if you have something draining the battery.
turn everything off in the vehicle.Then unhook one of the battery cables and put a small 12 volt test light in series with the cable.
"one lead to the bat the other to the cable" and if the test light glows there is something draining the battery.For a very small drain
you can use a milli amp meter in series.If it is draining overnight
it schould light the light.Dont forget to unhook the under hood light when doing this test.


Larry

 

Yea, alternators leave the factory (or the rebuild bench) bad. My friend just had his replaced this past weekend and the replacement was bad.

I agree that it sounds like a drain somewhere and not a bad alternator. The test light between the battery and cable is a good quick check. I usually leave it connected and start pulling fuses until the test light goes out. That narrows it down which circuit the short is on. Then I'd just start unplugging stuff on that circuit til you find it.

My old jeep cherokee had two major shorts. The garage wanted $50/hr to trace them so I did it myself using this method.

Hope this helps!

K.