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2000 Olds Bravada starting problem

Discussion in 'Electronic Repair' started by [email protected], Oct 26, 2013.

  1. Guest

    I now that this is really not the forum for this but I'm hoping that someone can help me.
    My 2000 Olds Bravada wouldn't crank.
    There was 12V present on one of the coil terminals with the key on.
    There is a small module next to the coil with a 4 terminal plug. It
    looks like it's on a heat sink with silicone grease. I don't know if
    this is an ignition module but it also had 12V on one of the
    terminals as well with the key on. I checked all the fuses relating to
    "ignition" and swapped the starter relay in the fuse box in the engine
    compartment with another of the same type but it made no difference.
    When you turned the key to start there was a soft "click" sound like a
    relay, which seemed to come from under the dash on the passenger side.
    Don't know what this is. The starter is oriented so that the solenoid
    switch is inaccessible and therefore it's impossible to get a meter
    onto the coil terminal. I removed the two bolts holding the starter,
    (this is the smallest starter I've ever seen on a car, so at least
    it's light), and I was able to turn it a small amount but the wires
    are so short and up on top I still couldn't get a meter on it. And of course I
    didn't want to try to crank it while it was hanging. That could have been areal
    disaster if it just decided to crank. So I thought that I'd have to
    remove it to test the solenoid coil wire and then bench test the
    starter as well, but I wasn't sure if I could have gotten these wires off. I was really stumped until I called my son.

    Mike came over to take a different look at this thing and he
    realized that you get to the starter terminals by lifting the rubber
    flap in the wheel well. I remounted the starter and we monitored the
    coil terminal on the solenoid while holding the key on, and it was
    dead. So while I was going to get a small alarm battery to put 12V on
    the coil to see if it would energize. Mike double checked the fuses. I
    heard him say: "Dad, I thought you said that you checked the fuses"?
    Well I did check everything that mentioned "ignition," overlooking the
    10 amp fuse that said "crank". That fuse had opened up and it appears
    for no reason. I haven't measured the current through that new "crank"
    fuse but since replacing it the car has been started at least 20 times
    without a problem. So I get the dummy of the month award for sure. But
    it does beg the question what opened that fuse?

    Now I know from dealing with high inrush current circuits in some TV
    sets that we'll sometimes find an open fuse for apparently no reason.
    The theory is that repeated heavy instantaneous loads will sometimes
    weaken a fuse element and then it may fail as in this case for no
    apparent reason.

    Well I thought that this was what might have happened until my wife
    called me from a supermarket parking lot the other day where she was
    stranded with apparently the same symptoms. I picked up a box of
    10 amp fuses along the way and upon arriving found a blown crank fuse
    again. With a new fuse the car started right up and has been OK for
    two days now.

    I have asked her to describe the symptoms and the events leading up to
    them exactly as she remembers them each time this has happened. She
    tells me that in each instance there was no sound from the starter.
    Apparently not even a momentary attempt to crank when the key was
    turned. That suggests to me that what took these fuses out was a dead
    short between the ignition switch (output) and the solenoid wire in
    each case that the key was turned. The problem is that it seems to be
    an intermittent dead short. I have no wiring diagram for the car but
    I’m thinking that 12V must go from the 12V bus, through this 10 amp
    crank fuse, through the ignition switch, then possibly through a relay, andthen to the solenoid terminal on the starter. So if that is correct then perhaps the problem is a chafed wire that could be anywhere beyond the ignition
    switch (output).

    For the time being I’ve showed her how to change the fuse in a pinch,
    but naturally I have to fix this. I’m almost ready to wire a starter
    button with a separate ten amp fuse from the battery right to the
    solenoid. I know about neutral safety switch concerns and so naturally I’d rather not have to but I’m not sure how to find this otherwise.

    Can someone please take a look at the schematic if they have it available and please tell me if I’m correct in my guess as to how the starting circuit is actually configured? And if you have any other ideas I’d appreciateyour input. Thanks for any assistance,
    Lenny
     
  2. John-Del

    John-Del Guest

    If the fuse doesn't blow again, just count it as a vibration\fatigue failure. This happened to me the other night. Get a 2AM phone call, my son is stuck at a gas station in my old 95 Windstar. AAA tows it home, and the battery is almost dead (10 months old), and it's not charging. Because it's original and over 200K miles, I pick up a new one, put it in, and still no charge.

    I found a 15 amp fuse open in the fuse box that fixed it. Looking at it closely, it wasn't burned, just had a tiny open section right at the "hump". I'm sure the alternator brushes had to be near gone, so I left the new alternator in it.

    Your wife's car may have two problems; an intermittent starter solenoid and the random fatigued fuse that blew just to ad interest to the problem.

    John
     
  3. Guest

    There are a lot of wiring diagrams online, if all you care about is
    installing a stereo or alarm. :)
    http://alarmsellout.com/support/diagrams/vehicle/OLDSMOBILE BRAVADA 1991-2004.pdf
    says the starter wire is yellow, if that helps.

    In that direction, you might look under the dash, below the steering
    wheel, for any signs of an aftermarket car alarm installation. They
    often cut the starter wire and splice it to wires from the alarm box;
    the alarm box has a relay in it so it can stop the starter from running
    if it wants to. If this added wire is grounding out somewhere, it might
    be blowing that fuse.

    If you live in or near the big city, the public library (often just the
    main branch) may subscribe to the "Mitchell" auto repair manuals. These
    are the ones that independent shops subscribe to; they are the closest
    you are going to get to a factory manual without paying factory-manual
    prices. They are much better than the typical Haynes, Chilton, etc.
    The catch is that they don't circulate; take some change for the copier
    (or a phone/camera to take pictures of the pages). They may also have
    some online manuals, but print a test page before you print the whole
    schematic; some of the earlier manuals were scanned at as much as 10 dpi
    and you flat can't read the diagrams. Also, take a turn through the
    regular stacks as well; sometimes they have real factory manuals sitting
    on the shelf. Again, non-circulating, but handy.

    If you get really stuck, the Haynes manual you want is #24071 at your
    friendly local auto parts store. (The headline on the cover is Chevy
    S-10 and GMC Sonoma.)
    Usually the ignition switch has one or two big feeds from the 12 V bus
    and everything else is "downstream" of that. This image is for a
    different problem on a '97 Bravada, but it shows how the crank fuse
    gets power (far right of diagram):
    http://www.dewitzdiagnosticsolutions.com/wp-content/uploads/2011/07/97_bravada_fuse_diagram_big.jpg
    (The entire page is at
    http://www.dewitzdiagnosticsolution...tart-no-fuel-pump-1997-oldmobile-bravada-4-3/
    ).

    Matt Roberds
     
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