Posted: 12/15/2006 7:39:06 AM EDT
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Howdy. I have a 1994 Caprice Classic wagon that has electrical problems. With the engine running I have a little over 14 volts at the battery terminals most of the time. With the engine off I have a little over 12 volts at the battery terminals all of the time. The problem is that when I turn on the wipers or press on the brakes or turn the fan from off to high there is quite a voltage drop - sometimes to below 11 volts. However, this problem is intermittent. I know I can get the battery and alternator tested for free at autozone, but the problem is intermittent and I would really prefer learn a little more about electrical system troubleshooting if possible. Any tips on where to start? Thanks, J. |
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easiest thing to do first would be to replace the solenoid. they're cheap, and as long as you can find the solenoid, they're easy to replace. i'm not familiar with the caprice, but 9 times out of 10 replacing the solenoid is what cures over voltage to the battery. worst case scenario: your alternator is pushing too many volts, and that's time consuming and expensive. go with the solenoid first though. |
| I'd have the battery load tested and inspect the battery cables, make sure they are tight and clean, also check that all body, and motor ground straps are in place. Voltage dips are not uncommon in older cars, and shouldn't cause any real problems when the vehicle is running, electric motors such as the wipers and power windows may move slower than they originally did when the car was new. |
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I would check your grounds very well, that is likely where your problem is. You may want to check with the parts places and see if they still sell single vehicle subsrciptions to Mitchell on Demand, with that you should be able to find out where each ground is located on your vehicle. Of course your vehicle is older, the motors and switches are old and worn, so there may be an actual problem there, but I would want to check the grounds first. A bad ground can cause all kinds of wierd problems ranging from mildly annoying to keeping your vehicle from running at all. |
| A little over 14 volts running is well wihin the normal range for your charging system. How old is your battery? How many amps is your alternator? I would load test your battery first. It may be simply that your battery cannot handle load, and your alternator is maxed when trying to compensate for it. Also checking your grounds is always a good idea anytime an electrical issue arises. Get your battery tested first, your alt is probably ok. |
| alternator is not cranking the amperage needed.........quick test...watch amperage while at idle..now, bring idle up to about 2k..ok?...turn on the headlights, note amp out put, turn on the heater fan, note amps....the Alt should be cranking out max amperage around 80 or so amps...probably higher...if not...replace. |
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12.3+ volt is fine (key off). 13.8+ volt at idle is good. with car running (idle), turn on headlamps, voltage may did withthe demand, but come right back up, keep adding load (wiper, hvac fan, hazard), should stay above 12 volt and hear the alternator whir (charge) as loads being run by alternator... if voltage keep going lower/below 12V as loads added, alt is not keeping up. |