Schematic for 98 SL2? 10 amp body fuse blows

Discussion in 'Saturn S-series' started by Mikey, Oct 12, 2008.

  1. Mikey

    Mikey Guest

    I have a 1998 SL2 and the 10 amp body fuse blows. Tried a 20 amp
    (danger!) and it immediately blew, too.

    The dome light doesn't work, is it on that circuit? The side towards
    the switch behaves like a switched ground connection:
    0 ohms in the 'on' position.
    20-25 ohms in 'door' position.
    open circuit in 'off' position.

    The other end of the dome light shows a couple ohms to ground. All
    of this is with the bulb removed.

    Seems like a short to ground somewhere.

    Are there any schematics online? I have the Hayes manual and it gives
    a general guide for a 94, which doesn't really help. I need connector
    locations and wire colors.

    Any ideas?

    Mikey, Oct 12, 2008
  2. Mikey

    navaidstech Guest


    looks like you have a short to the ground somewhere between the fuse
    and the dome bulb. This fuse also provides power to the MAP lights as
    well as your trunk light.
    All three should be affected by your problem. Finding it will be a
    heck of a project. YOu might get lucky by measuring the resistance
    from the orange wire to ground on all three lights, whichever is the
    lowest will indicate that the problem is near there.
    Wires normally travel in bundles, I can't see the problem occurring
    there. However, I would try to trace the wires as they leave the
    bundle and head to their final destination...quite possibly the
    insulation has been rubbing against a passthrough hole, exposing the
    wire to car's body.

    Good luck

    navaidstech, Oct 17, 2008
  3. Mikey

    Mikey Guest

    I'll try tracing the wires. The main library for the area has the
    official Saturn manual, the giant one that costs $$$ and it had some
    good info.

    The instrument panel body fuse feeds the three lights you mentioned
    along with the door lock switches (which also don't work) and the data
    link connector.

    Here's the bit that seems iffy: The wires come off the back of the
    fuse panel, all are orange and the manual gives the location of each.
    If I could take the wires off each circuit could be checked
    separately. There is a bolt on the back of the fuse panel. Does the
    fuse panel come apart?

    Another possibility is a "fox and hound" circuit tracer. The "fox"
    generates an audio or RF signal and the "hound" picks it up. Anyway,
    I'll poke around this weekend and see what's going on.

    Mikey, Oct 17, 2008
  4. Mikey

    navaidstech Guest

    Fox and hound might work but you have to be careful as RF from one
    wire might induce into wires next to it and you will end up with a
    signal all over the place.

    The fuse panel does come apart but I suspect putting it back together
    would be quite a challenge it it's build the same way as the underhood
    junction box. UHJB has a network of interconnections inside and I
    wouldn't even touch it with a 10 foot pole....I might wrong though -
    the fuse box might be built differently.

    If you have sharp DVM probes, you might be able to pierce the
    insulation of the wire and trace them that way.
    navaidstech, Oct 19, 2008
  5. Mikey

    Mikey Guest

    Spent some time over the weekend. Took off the door lock switches and
    trunk light to get to the wires. A check with an ohmmeter gave the
    same (low) value to ground everywhere. Somewhere around 2.5 ohms.

    I took off the rear deck cover to get to check the wires back there
    for cuts (there were none) and cleaned the splice pack connections.
    After that the resistance to ground was ~1.5 ohms, definitely less
    than before. Perhaps the short is to ground in the back of the car?

    Next plan: Take the 6 orange +12 wires from the body fuse. One at a
    time, cut the wire, check resistance to ground for that portion of
    theh circuit, and if good, put in an inline connector.

    If it's a short to ground, follow it. If it can't be followed leave
    it disconnected and tape it up. My guess that just one of the six
    wires has a short.

    Fox and hound usage: What is needed is one that does inductive
    coupling and can detect current flow. The ones that use RF and
    capacitive pickup probably won't do it. Too bad most look like they
    use capacitive pickup.
    Mikey, Oct 21, 2008
  6. Mikey

    navaidstech Guest

    There is one more method that would quite accurately pinpoint the
    location of the problem and it's using a device called a TDR (Time
    Domain Reflectometer).
    We use it at work all the time to pinpoint problems in RF transmission
    lines. It can, quite reliably, tell you how far from the end of the
    line to look for a short, open or what have you. Unfortunately it's
    beyond the budget of an average backyard mechanic.

    In any case, good luck. Keep me posted what you find. I'll be more
    than interested to learn where the problem was.
    navaidstech, Oct 24, 2008
  7. Mikey

    Mikey Guest

    We had some nice weather and I found out where it is...

    There are 6 circuits off the body fuse. I cut them one at a time and
    added an inline connector. The problem was with the driver side door
    lock switch. It is now disconnected and everything else works OK.

    Next job is to take the seat out and follow the wire bundle under the
    carpet and to the door. Or perhaps take the outside door panel out
    and start from that end. My guess is that it is in the door or where
    the wires go into the body - that's where they move the most and it is
    an intermittent problem.
    Mikey, Nov 2, 2008
  8. Mikey

    navaidstech Guest

    I was wonderign what was happening with your endeavours.
    Good stuff, you're almost there.
    navaidstech, Nov 5, 2008
  9. Mikey

    Mikey Guest

    Kid took the car to college. No more work on it until Thanksgiving
    Mikey, Nov 5, 2008
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