Bad battery or Bad immobiliser

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by pgc100, Jun 12, 2012.

  1. pgc100

    pgc100 Junior Member

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    I have an Optima Yellowtop and I have turned SKS off for troubleshooting.

    There are times when I open the doors get in and everything is dead. A few seconds later, the lights come on, I hit the start button and it fires right up. My Radio gives me a voltage check goes from 12V to 14.2V. I measured cold battery voltage this morning and it was 12.6V.

    Sometimes, I pull to a stop, put in park hit the power button to shut off as I pull the fob from the ignition holder, the car powers itself back up. I end up holding the key in my hand and the car running in accessory mode. The CD player cycles and the clock resets to 1:00.

    I pull to a stop, put in park hit the power button to shut off and it goes dead.

    I come back to the car, open the doors, very faint bulb but car won't start. I suspect in this situatution that I got out of the car, walked away and the car has started up into accessory mode and drained the battery. At this point I connect the car to a Battery I have started carrying round with Jump leads. This boots the 12V system and allows me to start the car.

    All I can think off is that I have a big short to ground somewere or a bad immobiliser.
     
  2. qbee42

    qbee42 My other car is a boat

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    Most likely you have a bad battery or a bad connection. Check the ground strap from the battery, then check all of the connections.

    Tom
     
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  3. fuzzy1

    fuzzy1 Senior Member

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    That would be an 'open' to ground, not a 'short'.

    I'd reiterate Qbee's suggestion to check the battery connections. Your symptoms are vaguely similar to what I had on a new car decades ago, with dealer-installed AC. The first several times, jiggling various things in the engine compartment got it going. Then I noticed the ground strap to the engine block was loose. It had been removed during the dealer work, but when replaced the bolt was only partially threaded in, never fully tightened.

    Unfortunately there are many places where a similar bad connection could cause this problem.
     
  4. Patrick Wong

    Patrick Wong DIY Enthusiast

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    As Tom indicated, a loose battery cable is the most likely. Three places to check: the positive terminal connector at the battery, the negative terminal connector at the battery, and the negative cable at the body. The OP should visually inspect all three places and tighten the associated hardware. If any corrosion is seen, for example at the body, the parts should be disassembled, cleaned, then reassembled and tightened securely.
     
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