Search Auto-Repair-Questions

Wednesday, October 29, 2014

2001 Buick Lesabre electrical issue

So the other day my air pump went to s*** so I unhooked it but before I could I tripped
the checks charging system light on my dash and once I got it on hooked my voltage in my cluster want to almost 17 volts so I had the alternator rebuilt and it solved the problem for about 20 minutes where it ran 14.6 volts and then went back to the 17 so I grabbed another used alternator from my local you pull yard that one lasted about 30 minutes and did the same thing I've checked all
wiring found no issues of broken casing no corrosion no missing grounds does anybody have any ideas


  1. I had a Dodge truck that did something like that, it was the computer that went bad.

  2. my first instinct would be a bad alternator ground or a bad engine ground strap. The engine must have a good ground to the frame and body. Seen it before lots of times

  3. What the others said about this could be true, especially a poor
    ground, assuming that your alternator has the regulator built-in (find
    that out, but it's probably so). You should see a grounding strap or
    two between the engine and the car frame or unibody. Once you find it,
    inspect it (or them, if you have two or more) to see if there is
    corrosion, rust, etc. where the strap (possibly a braided copper
    strap) connects to the engine and the frame/body.

    If it looks suspicious, you can disassemble the connection and clean
    all mating parts, then reassemble, using new bolts/nuts where possible
    if needed.

    You can test for a poor connection with an ohmmeter (volt-ohmmeter).
    You should have a very low amount of resistance (a fraction of 1 ohm)
    between the engine and frame/body. You can also have someone hold the
    connections while you wiggle the grounding strap. The resistance
    should not change. If it does, and especially if it goes into high
    resistance (more than an ohm), you have a problem there at one end of
    the strap. And if you have two straps and this happens with one, the
    other must be bad or it would have made the connection with low
    resistance even if another strap were missing.

    You can get one of the $5 to $10 Harbor Freight volt-ohmmeters
    (VOM's). They have digital readouts and they are easy to use. Get one,
    if you can, that uses "regular" batteries, like AA or AAA, instead of
    a button cell or a strange size as it will be easier to replace a
    standard battery. Make sure you turn off the VOM when you're done
    using it, and never measure voltage in the ohms positions, and never
    measure AC volts with the DC positions (same for current--it's just
    best to not be measuring current unless you know what you're doing,
    but the worst you could do is blow the meter and cause a fire if you
    tried to measure a car battery using the current position across the
    two terminals. Also use the correct range for measuring (always go
    higher rather than lower than what you expect--you can always change
    the range downward if you need to).

    The better meters have auto-shutoff and some of the cheapies do now

    Rather than continue to mess up good alternators, if you can't find th
    eproblem, you might find an honest mechanic (there are some around,
    believe it or not) to find the source of the oroblem but tell them
    everything you tried to save them from destroying an alternator or two
    before they find the problem.