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Saturday, June 15, 2013

battery cables reversed on 1994 Lexus

A friend reversed his battery cables and blew some fuses. He also tried to start the car. I've replaced all the fuses I can find blown. The car turns over but will not start. Any suggestions before I tell him to tow it to a garage?


  1. Be ready to purchase an ECM, costly.

  2. Thanks. that's pretty much what I figured but he wanted to check if
    if I might have missed something.

  3. Is there a fusible link that might have burned out? It looks like a
    regular wire. There was a wire connected to the positive battery cable
    connector that ran along the inner fender and then to the firewall. In
    th emiddle of this was a red wire with a connector on each end that
    was aprt of that wire's circuit. It was made so that if it got too
    much current, it would get hot and melt the wires. It acted as a
    slow-acting fuse.

    In my case I caught it fast enough to prevent it from burning out. The
    insulation cover melted for the most part so I wrapped it with
    electrician's tape and it lasted as long as I had the car.

    Assuming that there might be one of these, I would think it would be
    visible somewhere near the battery or running from a power
    distribution block of some sort.

    If it doesn't have one, then you might have fried the ECU or something
    else that prevents the car from starting.

    Does it have power to anything else except the starter circuit? Do the
    headlamps, interior lights, brake lights, radio, wipers, washer, etc.,
    work OK? If they don't, the trouble may be something other then the
    ECU since that doesn't control the lights and accessories circuits.
    Then you could test for voltage at various points along the wiring
    harnesses to see where the circuit no longer connects to the battery
    because of an open circuit. Find where it's open and you may have
    found the problem. It could be a hidden (not easily visible) fuse or
    fusible link.

    If the lights and accessories do work, see if you can find the ECU and
    see if it looks overheated. That's not a sure fire way to tell if it's
    burned up inside, but if it looks like it's had heat applied to it,
    it's a good bet that it is gone.

  4. that's an expensive mistake..oops!