Stop Start

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Dustysweeper
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Stop Start

Post by Dustysweeper »

Stop Start hasn't worked for a while now, because the battery was old and only holding less than 70% charge. The accumulateor reports at 30%. Well the battery finally gave up last week and sent the dashboard into Christmas tree mode. The date on the battery 6.2014, so it done well.

I replaced the battery like for like a week ago and cleared all TDCs, yet still have no Stop Start. The battery is at 96% charge, but the accumulateor is still reporting only 30%. The only codes returned by Diagbox are related to the drivers door keyless entry having an open circuit, everything else is good.

Could it be the accumulateor is faulty?
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GiveMeABreak
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Re: Stop Start

Post by GiveMeABreak »

You have one of the older systems which uses energy accumulators as you mentioned. Later systems have done away with all that and just use the main battery and updated starters.

10 years for your main vehicle battery was pushing the boat out a bit :-D and you've had it roughly twice as long as recommended. With the accumulator capacitor at 30%, I would suggest that you drive the vehicle for a week or 2 normally and see if there is any change, now with the new main battery to see if it makes a difference. It always takes a good 24 hours minimum for the Battery Charge Status Unit to record the new main battery and to calibrate properly.

If there's no change to the charge status off the energy accumulator, then it may well need a replacement if you are bothered with it operating or not - but be warned there are special measures you need to take before removing it, as it must be discharged first using specialist equipment as these still carry quite a belt!

If you are getting a message "Engine Fault: Have the vehicle repaired" and a fault code of P1A9C, then the energy accumulator terminals need to be checked for tightness and if all are in order, the "Reinitialisation of the central voltage maintaining device" procedure needs to be undertaken using the guided procedure in Diagbox.

Ideally if you can run a global test in Diagbox and report any codes, it may help as there are several scenarios why it may not be working and the fault codes may determine what the issue is before replacement.
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Marc
Dustysweeper
Donor 2023
Posts: 56
Joined: 29 Jan 2023, 17:26
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Re: Stop Start

Post by Dustysweeper »

Thanks for your response Marc. Informative as always. 🖖

I've just completed a 200 mile round trip and happy to say that when I stopped at home the Stop Start (eco) kicked in. So it's working. It was an aged battery that stopped it from working just over a year ago. All good now.👍
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GiveMeABreak
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Re: Stop Start

Post by GiveMeABreak »

Great, sometimes these need a little time to calibrate with a new battery, but can also mean some electrical systems don't get enough power on weak battery with everything else going on to work properly.
Please Don't PM Me For Technical Help

Marc