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  #1  
Old 09-12-2005, 06:10 AM
94svxred 94svxred is offline
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Question about the ECU?

My car sits in the garage , sometimes for a week maybe two before i start it or drive it . So here is the question ,If the battery gose dead and can't start the car! To what point will the ECU reset or in my case there is still a little bit of juice but not enough to start the car?( basicly a dead battery) Is the ECU still working or will it reset? Is this bad on the ECU or should I disconnect the battery when my car sits?
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Old 09-12-2005, 08:51 AM
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If the battery goes completely dead, the ECU will reset. Its not a problem for the ECU. It will relearn the optimizations when you start driving the car again. Takes a few gas tanks.
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Old 09-12-2005, 04:45 PM
oab_au oab_au is offline
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ECU cutoff.

The battery would have to have, no sign of life at all, to cause the ECU to clear. No dash lights, no nothing. It only takes the smallest current to keep the ECU memory up.

My car can spend a couple of weeks in the garage, without the battery going low, may be your battery is 'past the use by date' , or you may have a leak in the electrical system.

Harvey.
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Old 09-13-2005, 02:25 AM
94svxred 94svxred is offline
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Thanks for the replies !
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Old 09-13-2005, 02:32 AM
94svxred 94svxred is offline
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Quote:
Originally Posted by oab_au
The battery would have to have, no sign of life at all, to cause the ECU to clear. No dash lights, no nothing. It only takes the smallest current to keep the ECU memory up.

My car can spend a couple of weeks in the garage, without the battery going low, may be your battery is 'past the use by date' , or you may have a leak in the electrical system.

Harvey.
We just moved recently and the car sat outside for about a month at laest before i tried to start it , due to being very busy with the new house kids and work . It wasn't completly dead (lights come on etc.) just not enough juice left to start her up! So i guess this means the ECU memory is still in tack. Part 2 of my question is then if I dissconnect the battery, How long would it take for the ECU too clear the memory? 30sec.,1hr, overnight????? Just curious
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Old 09-13-2005, 04:49 PM
oab_au oab_au is offline
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Quote:
Originally Posted by 94svxred
We just moved recently and the car sat outside for about a month at laest before i tried to start it , due to being very busy with the new house kids and work . It wasn't completly dead (lights come on etc.) just not enough juice left to start her up! So i guess this means the ECU memory is still in tack. Part 2 of my question is then if I dissconnect the battery, How long would it take for the ECU too clear the memory? 30sec.,1hr, overnight????? Just curious
Yes the memory would still be there under those conditions. Gee I remember reading that somewhere, 1 minuit should do it , but it depends on the amount of residual current, stored in capacitance, in the electrical system. Some say to disconect the battery, and touch the cables together, but this could lead to trouble if it was done wrong. I think it would be safer to disconect the battery, and turn the ignition and lights on, for about 1 minuit, to waste the the system out.

Harvey.
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Old 09-13-2005, 05:17 PM
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It won't hurt to just let it sit overnight with the battery disconnected.
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