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XC90 '02–'15 General Forum for the P2-platform XC90 model |
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The simplest things……Views : 1242 Replies : 16Users Viewing This Thread : |
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#11 |
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Last Online: Today 00:00
Join Date: Apr 2011
Location: Belfast
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It does work if you're having issues such as those posted by the OP. Pulling fuses and unplugging certain components with the battery connected or the ignition on can corrupt multiplex systems. Touching the cables together forces the modules to start from scratch the next time they are energised. Providing the software hasn't been corrupted (unlikely), this procedure can be quite effective.
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#12 |
Me ? Surely Not!
Last Online: Apr 25th, 2024 19:48
Join Date: Jul 2010
Location: 2007 Volvo XC90 D5 Geartronic. South of Hadrians Wall.
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I agree which is why I clearly stated follow the procedure in the handbook.
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“Do the right thing. It will gratify some people and astonish the rest.” – Mark Twain 😊 2007 Volvo XC90 D5 SE Geartronic |
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#13 | |
Bungling Amateur
Last Online: Yesterday 23:45
Join Date: Aug 2014
Location: Beverley, East Yorks
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- Software is held in non volatile memory (nvm) in modules and cannot be corrupted or changed by power cycling. - The suggestion touching the battery + and - cables together whilst the car has no power to force a deeper restart is fanciful. With no power to the car, processors are not running, nothing is monitoring, no heartbeat or communication on the buses, it's a hocus pocus theory - To the contrary, if there was any residual power in any system after the battery has been disconnected (i.e. a charge stored in large smoothing capacitors on module power supplies), you run a completely unnecessary risk of damaging the electrics by creating a zero ohm short circuit between the supply and ground feeds, which could result in a momentary but significant power surge and a back EMF spike If you really feel the need to try this suggestion - connect a resistive load between the +ve and -ve terminals such as a tail light or interior light bulb - on a 1980's car (with logic arrays rather than microprocessor controls) it may have occasionally made a difference but not on a modern Volvo. If you’re still going to challenge me and promote it as a solution - give us a technical explanation as to how it makes any difference…. Find a post on here where someone has corrupted software on a module and it had to be reloaded?
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2011 XC90 D5 Executive 2003 C70 T5 GT 2012 Ford Ranger XL SC 1977 Triumph Spitfire 1500 1976 Massey Ferguson 135 Last edited by Tannaton; Jul 3rd, 2023 at 09:30. |
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#14 |
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Location: Belfast
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There's nothing cobblers about it. At no point did I say that software WOULD be corrupted. I mentioned that it was unlikely. What I did say was that multiplex systems can be corrupted, or rather behave in a way that you otherwise wouldn't expect them to when interruptions are introduced. Draining residual power (and we're talking very small amounts here) can and often does fix spurious behaviour in automotive applications. It is something I wouldn't recommend doing on more modern vehicles as there's an increased risk of causing damage to the electrical systems.
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#15 |
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Last Online: Yesterday 17:00
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Location: Chichester
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Car started just fine this morning and the On Call Service Required message has gone, so all good.
Question though...can anyone explain why the car just decided to start? It may help to know that I put my Ctek charger on it for a few hours before trying yesterday evening, but personally I would think that's not relevant as the Varta battery is only a couple of months old and I drove 550 miles last Friday. As ever, thoughts welcome! ![]() |
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#16 | |
New Member
Last Online: Jul 6th, 2024 10:26
Join Date: Feb 2023
Location: Lincoln
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My bet is you have the same corrosion causing slightly high resistance. Thus, the ctek gave your battery the extra boost it needed when the battery terminals were loose. Mine struggled to start unless I fully did up the terminals until I got rid of the high resistance. Good news is yours is starting without problems now. So I wouldn’t worry. But if you get problems starting in the future, check the main cables in the engine bay by the fuse box and main earth post. Chances are a good clean and you will be all good again. |
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#17 |
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Last Online: Yesterday 17:00
Join Date: Apr 2011
Location: Chichester
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Funnily enough……car is currently reporting engine service required, brake assist service required and an anti-skid issue.
Could it all just be grimy connections? |
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