electrical problems

[johnceggleston]

i went to start my 97 obw w/ 110k miles, automatic, this just after a 3 hour drive home. when i turned on the key every thing lights up as normal, when i turn the key to start, it al goes dark, dash lights, headlights, warning lights, dome lights...everything dark and the car wouldn't crank & electric locks wouldn't work. no clicks, no nothing.

 

the next day, it acted a little like a weak battery, and over time system lights slowly came back and it finally started. i checked the battery voltage while off, 12.58v and after i got it running, 14.88v.

 

this is wierd, my first fear was the computer. any ideas on what or where to check next?

 

thanks, john

[mtsmiths]

I'd check for a loose or corroded ground connection. Trace the main ground (and any others you see) to the block. Carefully remove them and clean the block (or other connection surfaces) and the eye. Spread on a little bit of dialectic grease (or a shot of silicon spray) and reassemble nice and tight.

 

I'm betting your problem will go away. If not, at least you've eliminated the most common fault for free, and you know you really have 'something' wrong.

 

Good luck, and Happy New Year.

[nipper]

i agree claen all your main connections and terminals. YOu may want to have the battery load tested after you cklean all the terminals just to make sure.

 

 

 

nipper

[OB99W]

I also agree with the suggestions to clean terminals and other connections. There's a remote possibility that your battery has a damaged internal cell connector, but a bad connection is more likely, so you might as well start there. Don't be fooled by things appearing to be clean and tight; sometimes corrosion can form between metals where it isn't obvious. Of course, if you can see an obviously bad spot, begin with that.

 

Another thing - if possible, use either a wire brush or file to do the cleaning. Some people use "sandpaper", which most of the time is actually some form of metallic-oxide type abrasive. The problem with that is unless you thoroughly clean off the connection before reassembling it, you can leave behind those oxides; they aren't good conductors, and will actually limit how much metal-to-metal contact you wind up with.

[color-blind]

Have your battery and alternator tested, sounds like a failing battery. The most common problems are batteries, alternators and starter contacts. Just because the alternator produces voltage does not mean it is good. The alternator needs to be tested with a machine that can also test the diodes. A good Subaru shop will have such a machine. Hope this helps.

[cookie]

I'd go for battery as most likely too. Connections are always a problem but it sounds like you are getting decent voltage when it is running. Like CB says the next bet is starter contacts but when I have seen that it did not dim the lights when you attempted to start.

Load tests are nice when you have a tester. Got a pal who will loan you a test battery?

[color-blind]

I'd go for battery as most likely too. Connections are always a problem but it sounds like you are getting decent voltage when it is running. Like CB says the next bet is starter contacts but when I have seen that it did not dim the lights when you attempted to start.

Load tests are nice when you have a tester. Got a pal who will loan you a test battery?

 

Here's a little bit of information for ya. Load testers are now going away and being replaced with conductance technology. With tools from Midtronics one can easily test the battery, alternator and starter-with extreme accuracy. Depending on where you live battery life will vary. In Seattle the average life of a battery is 4-5 years. Here is a link to a good machine.

 

http://www.midtronics.com/main.php?Category=Transportation%20Applications&SubCategory=Battery%20Testers&MarketSegments=Auto/Light%20Truck&recordID=84

[cookie]

Oh boy, that adds to more stuff I want. It's been more than ten years since I was a shop manager and I'm sure everything has changed. A code reader used to be somebody who worked for the CIA.

[cookie]

And by the way down here in SF after years of testing on fleets I have found that if I change batteries at four years I brought the on road failure rate to near zero. That sounds similar to your experience. I expect the guys in hot and cold states need to use different numbers, probably heat is worse.

[color-blind]

And by the way down here in SF after years of testing on fleets I have found that if I change batteries at four years I brought the on road failure rate to near zero. That sounds similar to your experience. I expect the guys in hot and cold states need to use different numbers, probably heat is worse.

 

You are correct heat is worse. A friends shop in Arizona informs me that average battery life is 3 years. Have a good weekend.

[OB99W]

i checked the battery voltage while off, 12.58v and after i got it running, 14.88v.[...]any ideas on what or where to check next?

John, since you apparently have a DVM, you could look for bad connections using the "voltage drop" method. That's done by putting a probe of the meter on one side of a connection, and the remaining probe on the other side. For example, to check a connection to a battery terminal, put one probe on the post and the other on the cable clamp at the same terminal (+ or -). Any reading other than zero or very slightly more (less than 0.01V!) indicates a resistive connection that should be cleaned. In order to have sufficient current flowing for this type of test to work, you need to load the battery. That can be done by running headlights, preferably with high beam, and possibly accessories; with many Subarus you'd have to have the key "ON", but engine not started.

 

Another way to check voltage drop at the battery terminals is to load the battery as above, then take voltage reading two ways; the first from positive post to negative post, the second from pos clamp to neg clamp. Compare the two readings; any difference beyond about 0.01V means there's a bad connection at one of the posts.

[johnceggleston]

thanks for all the help. i'm out of town till tuesday, i'll run some test then. i know the battery isn't the best but i hate spend money hoping for a cure.

 

thanks again,

john