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Discussion Starter #1
Hey guys last time I posted here was about my alternator dying on me (march 2010).. I've not had any problems since then until this morning. I was driving to work at 60-70 mph, and the battery light came on, flashed off, and back on again. I figured it was the new alternator once again.. So I left at lunch, and the light didn't come back on until I was going high speed with the lights, radio, and AC on.. Pulled into a shop, and they said everything looked fine. I went to another shop, and they hooked up a tester for the battery and alternator.. Everything tested pass once again (battery/alternator, diodes).. Took it to an actual shop on the 3rd time (instead of auto zone/Oreillys) and he brought out another tester. Had me do some more thorough thing like rev up engine, turn AC on, lights, and then test it idle once again. He also said it passed everything, and the voltage tested good during all phases. That it might just be an electrical problems, and I may have to take it to a Ford Dealership.

I drove back to work, and the light never came back on after this.. On the way home after work the battery light came on for about 5-10 seconds, and then off again. I don't have a lot of faith in the tests/machines they used to test it. Last time I went to Oreilly's they sold me a new battery, and then the alternator went out a day after. Not really sure what my next step should be. Everything seems to be running normal unlike last time. There hasn't been any burning odors or smells, interior lights running fine. The mechanic seemed to be adamant that everything appeared fine with the battery and alternator. We spent about 5-10 minutes on it throwing a lot of different scenarios at it. Not sure if anything could replicate going 60mph down the highway. Any suggestions?

2006 Ford Focus ZX4 SE
84,600 miles
 

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Discussion Starter #3
What ever you do do not disconnect the battery while running to 'test' the alternator
see the following

http://www.troubleshooters.com/dont_disconnect_battery.htm

There are ways to get the cluster to read volts

I
would connect a voltmeter to the cigarette lighter and monitor the voltage when the light comes on
Thanks for the information. I'll try to procure a voltmeter. Do you know if those battery/alternator testers they use will show a problem if the light isn't on? I can only get it to come on so far while driving a highspeeds. It came on this morning with only AC/Radio, and driving 60mph for about 10 minutes. Have not seen it come on while driving low speeds. Is it possible the pigtail connector I've read about is getting moved around at high speed/vibrations? I'd also like to add I'm not having any problems with the car.. Idles fine, dash lights solid, etc. Just the light is coming on.
 

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"""Do you know if those battery/alternator testers they use will show a problem if the light isn't on? """

Intermittents are a tough fix. I say to my customers "If it works I cannot fix it!"
Besides the pigtail, I read on an English Ford forum how they were seeing broken wires leading to the alternator because except for a short length the wire was rigidly held in place and where it started to flex that is where the wire broke
 

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Hatch Nation #136
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Check your ground wires. You may have something loose or with a little bit of insulation stripped.

That would explain the intermittent nature of your light and the tests coming out good.

To put your car into diagnostic mode, hold down the trip meter button with the car off. Turn the car on while holding it and then cycle through the options to read the battery voltage. This one is fairly reliable, as that is the same sensor the car uses to turn on the warning light.
 

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Besides the pigtail, I have read where the wires going to the alternator are held rigidly in place except for a short distance to the alternator-just where the wires are allowed to flex is where the wires break

If nothing else, here is a descent YouTube about measuring the voltage. If you connect a voltmeter to a 12 volt power plug at least you can tell what the system is doing when the light comes on.
Yes one CAN use the cluster to monitor voltage-what I don't know is what happens when the car voltage goes 'nuts' will that affect the voltage reading from the cluster

http://www.youtube.com/watch?v=Bzz7P3qNHcE&playnext=1&list=PLE24EF935BFC9D8A4
 

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Hatch Nation #136
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Yes one CAN use the cluster to monitor voltage-what I don't know is what happens when the car voltage goes 'nuts' will that affect the voltage reading from the cluster
It will jump around and tell you the volts that it is reading. Which is what trips the light.

May not be safe to check at highway speeds, but then again, neither is a voltmeter.
 

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Discussion Starter #8
I got the diagnostics mode going while ago but wasn't sure which option I need to be looking at.? Would this also show if the alternator is going bad? Sorry for the newbie/idiot question lol.

Check your ground wires. You may have something loose or with a little bit of insulation stripped.

That would explain the intermittent nature of your light and the tests coming out good.

To put your car into diagnostic mode, hold down the trip meter button with the car off. Turn the car on while holding it and then cycle through the options to read the battery voltage. This one is fairly reliable, as that is the same sensor the car uses to turn on the warning light.
 

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Hatch Nation #136
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You should be looking for around 13 volts. Over 14 is bad, under 12 is unacceptable.

I think it is like the second or third on the list. It will either say ##.#V or ##bat.

With it only flickering on from time to time I would guess a bad wire, vs a bad alternator. However, when you had the alternator replaced, did you have it rebuilt, replaced with an advanced auto/autozone/major chain alternator, or a new alternator? A lot of the chain store rebuilds are crap and don't work right. I wouldn't guess that is your problem, but more info always helps.
 

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Discussion Starter #11
I had it replaced with a duralast from autozone.. What I find odd is that it is only coming on after a while on the highway at high speeds. I just drove around a low speeds and no battery light. I bet it comes on while driving home to work at high speeds 60-70mph.. I had my AC Running, Lights on, and radio on while driving while ago around on the side streets on lunch.


You should be looking for around 13 volts. Over 14 is bad, under 12 is unacceptable.

I think it is like the second or third on the list. It will either say ##.#V or ##bat.

With it only flickering on from time to time I would guess a bad wire, vs a bad alternator. However, when you had the alternator replaced, did you have it rebuilt, replaced with an advanced auto/autozone/major chain alternator, or a new alternator? A lot of the chain store rebuilds are crap and don't work right. I wouldn't guess that is your problem, but more info always helps.
 

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Hatch Nation #136
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It is possible that the chain store rebuild is at fault, but I have my doubts with the symptoms.

Try seeing if you can get the light to jump on by riding down a bumpy road. See if there is anything you can do to get it on with vibrations.

If it is the voltage regulator (the known fail point) you should see the car chugging pulling up to lights, things dimming under load, or something along those lines. Electrical stuff generally works or doesn't.

Have you looked over the pig tails and your ground wires?
 

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Discussion Starter #13
What is odd this go around with the new alternator is that I haven't had anything weird going on. Before when my last alternator went I smelled something burn one day and battery came on then off. I drove around for a while after that event, and a couple weeks later the radio acted weird.. Then eventually it just died.. As of right now no dimming of lights, burning odors, and the only time it comes on is highspeeds.

I haven't looked over the wires.. Don't really know what I'm doing to be honest but willing to learn and tinker to a point where I think I may mess something up, and then will stop. I know what the pigtail looks like so I was thinking of seeing if I can get the light to come on by moving it around some. The alternator that went out was a motocraft one.. It lasted up till around 70,700 miles.


It is possible that the chain store rebuild is at fault, but I have my doubts with the symptoms.

Try seeing if you can get the light to jump on by riding down a bumpy road. See if there is anything you can do to get it on with vibrations.

If it is the voltage regulator (the known fail point) you should see the car chugging pulling up to lights, things dimming under load, or something along those lines. Electrical stuff generally works or doesn't.

Have you looked over the pig tails and your ground wires?
 

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Discussion Starter #14
I got some numbers on the way home from the bAtt diagnostic tool from the odometer.

120 Idle sitting without car being started.

130-136 Car started with radio idle
130-136 Car started with radio/AC
130-136 Car started with radio/ac while driving low and high speeds.
123-125 Car started with radio/ac while at red lights
 

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my car's headlights/ dash lights started flickering at weird times on the highway. all tests showed the alt was good. it wasnt until I installed a voltage gauge that I saw it bouncing between 12v and 17v! replaced the alt and its been fine ever since.

did the batt light flicker while doing the above tests?
 

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Discussion Starter #16
Yes, for the first time it came on while I was driving 35 mph on a side road prior to getting on the interstate. When the battery light came on the voltage didn't change at all.

my car's headlights/ dash lights started flickering at weird times on the highway. all tests showed the alt was good. it wasnt until I installed a voltage gauge that I saw it bouncing between 12v and 17v! replaced the alt and its been fine ever since.

did the batt light flicker while doing the above tests?
 

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Hi Bradtech,

If you are unable to determine why it is having intermittent issues, you may want to consider having your dealer diagnose it. I'm sure you are getting tired of taking it in to all these different shops, but they will be best able to locate the cause. Please let me know if I can help in any way.

~Natasha
 

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I had this issue too. The dash would give me anywhere from 12.xxV to 13.xxV. After replacing with new alternator, it read a very solid 14.5V.
I would think about replacing again. Luckily it's probably still under warranty.
 

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Discussion Starter #20
I took it in to dealership. Confirmed the new alternator is going bad/weak. 12-12.5V when headlights/AC are on. The alternator is under warranty but I don't know if I want another Autozone brand even though the Motorcraft only lasted 70k that was in there.. Will be on my third alternator at 87000 miles.
 
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