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kmrobertson3

Help Flat Battery Possible Ecu Goosed

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Hi

I got back to my rav after leaving it 2 weeks to find it has a flat Battery. I manage to get hold of jump leads and another car. Only thing is I didn't leave it charging long enough an tried to start the car and it turned over a couple of times then nothing???

I am now worried I may have fried the ECU. Has this happened to anyone else? Are there any hidden fuses I should check? I defo need a new Battery but if there is no life am I looking at a new ECU?

Any help or pointers greatly appreciated.

Keith

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Hi,Keith.This is the time of year when dodgy batteries start to show.

How old is the Battery and how many miles do you normally drive the car,after starting, before this happened.?

A flat Battery will need charging,with say a domestic charger,for a minimum of 24 hrs.

I would say it is unlikely that the ECU has suffered.

As the only info you list is a Rav 4 with no model type or year this post can only be described as groping in the dark and so it would help the experts on here to give more detailed observations than I can

Del

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Sometimes a really flat Battery can go bad and will not recover. I would remove the Battery (or one terminal) and then fully charge the Battery, preferably with a charger that can recover from a low discharged state. See if the Battery recovers, if not replace it.

Aldi are doing great Battery chargers today

http://www.aldi.co.uk/uk/html/offers/special_buys3_26860.htm

I agree with Crofter, Its very unlikely that you managed to damage the ECU.

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Ahh sorry guys I should have said. I have an 2007 T180 diesel original Battery. The kids left the rear interior light on about 6 months back and I had to get a jump start then and the Battery recovered. I know I will defo need a new Battery this time but its more the fact I got the engine to turn over a few times then there was nothing which leads me to think I've fried the ecu.

Cheers for your responses.

Keith

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As the others have said, it's very unlikely you have damaged any of the ECUs. I'm not saying it's impossible, but take my word for it, the things are designed to take a reasonable amount of abuse and during design validation, they go through far worse tests than the equivaent of a jump start and a flat Battery. There are tests specifically designed to verify that the ECU doesn't corrupt its memory, through repeated resets, which might occur @ low Battery voltage.

Anyway, if there's a fault in the starting system, you may get a flashing amber light on the start button - look for that.

Another thing is that under a flat Battery condition, the steering lock ECU can get confused. In this situation the vehicle will not start. The way to reset it is to make sure the ignition button is in the "off" state first and then open and close the driver's door.

Get the Battery back to a good state of charge first or get a new Battery as deep discharge can reduce a vehicle Battery capacity serverely. Note, this doesn't apply to all lead acid batteries, it's just an unwanted side effect of the way vehicle starting batteries have to be designed to provide the initial hundreds of amps to turn the engine over.

Not getting at anyone, but it's amazing how everybody rushes to blame ECUs. I guess for many it's "witchcraft" and therefore not to be trusted. Yes, like anything else they go wrong, fail and may have an inherent design flaw, but they are generally one of the most reliable things on a vehicle (no moving parts).

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Ahh sorry guys I should have said. I have an 2007 T180 diesel original battery. The kids left the rear interior light on about 6 months back and I had to get a jump start then and the battery recovered. I know I will defo need a new battery this time but its more the fact I got the engine to turn over a few times then there was nothing which leads me to think I've fried the ecu.

Cheers for your responses.

Keith

More a case you have used yer auld Battery's dying breath, Keefo....after 5 years, time to get replaced. Doubt if it even had enough left in it to do anything t'ECU....

Big Kev

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I think it may have been the doner car being connected via the jump leads that caused the spike.

I am defo grtting a new Battery to try so fingers crossed this works. I take onboard about the ignition button light and open close the drivers door and will try that also if need be.

Thanks again guys.

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Never buy a new Battery until it has been trickle charged for at least 12 hours.

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As an aside to this thread, does anybody here replace their Battery before it starts giving grief? What Battery would have been originally fitted to my 03 petrol? There's a yuassa one in there now and judging by the state of the screws on the Battery cover, it's been accessed at least once.

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Hi,Bill.As it seems,to me,to make a change of Battery which is not giving any trouble is another strain on the wallet,so I can't give a yes to your first question.

The oem Battery fitted was considered by many on here to be a little on the small side and opted for the bigger one fitted on the derv powered ones.I did this when I had to change mine.

With a little bit of adjustmemt with regard to the repositioning ot the clamping rods this is do'able.although I thought the leads seemed to be a little strained and added a short copper link on one of mine.

If you are at all worried, a reputable supplier will check you Battery for free,so if you are in any doubt about that reputation try a couple of them

This has been covered in the past so maybe a lookee in the search section may help you.

Del

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What battery would have been originally fitted to my 03 petrol?

I can give you the figures for a 52 plate. Petrol manuals 27Ah , petrol auto 36 Ah and diesel 55 Ah. I have replaced mine (petrol man) with a 68 Ah which as far as I can remember is what Halfords say for the diesel.

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