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Discussion Starter · #1 ·
S60R 2005, at 160,000 miles the original battery died. Now I have a new one, but think that my 4C calibration over time was also lost, because now when I go over a bump, the front end bounces like my shocks are toast. They might actually be toast, but it wasn't happening before the battery died and am wondering if anyone has ever done this and if a SUM recal would fix. Thanks!
 

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Not a bad idea. However, I replaced my battery but haven't done a new sumcal yet. Seems ok to me.
 

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Just replaced my battery and haven't noticed any suspension issues. Feels exactly as it did before the new battery. You have no warning messages on your dashboard? I know there is an accelerometer plug back there near-ish the battery that if unplugged will disable the 4C, making it bouncier. That will also trigger a warning on the dash though.
 

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Everything from your ECU program to all the other programming in your other modules is stored in memory that doesn't need a battery to maintain itself, so your time without a battery can not be the direct cause of any changes, so you will need to direct your investigation elsewhere.

If this battery is much bigger than the old one that may be pushing the back of the car down a little more than before, but the old SUM is still in effect so even that shouldn't be an issue unless you try to calibrate and the rear position sensors are not happy.

As mentioned above, might want to make sure all is well at the rear electronic cluster by the batter since you were just in there.
 

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Discussion Starter · #5 ·
Coincidentally, my front shocks blew out at about the same time. 160,000 miles is pretty generous for fronts, long overdue.
 

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if a SUM recal would fix. Thanks!
Like chicken soup, it couldn't hurt! And, thanks to Chinese piracy, they're practically free. (I always click/do mine twice... sometimes it makes an underhood sound the 2nd time that it didn't do the 1st...) So even if it doesn't fix the problem... (FWIW: 1 experiment I've never tried is to disconnect the rear body accelerometer, but those who have done so report that it causes the rear to bounce up and down as if the shocks are mechanically disconnected...)

My SUM hacking project has led me into the land of unusual DTCs, the likes of which I'd only read of, and always hoped to eternally avoid... I've found that if I get (after I managed to trigger) an 'anti-skid temporarily disabled' msg, that I can clear the DTCs (or not), and the next time I start the car I'll still get that msg, but it will disappear on its own after I've driven 80~100 feet. And 4C will work again. For a few more driving cycles! After that the SUM stops trying, and a re-cal is required in order to re-enable 4C functionality.

I'd never done a re-cal after I had LCA bushings replaced (again) earlier this year. In general, I don't like doing re-cals because that means the SUM has to re-learn (re-adapt), and it learns by making (sometimes painful) mistakes, from which it 'learns', and it seems to be pretty callous when it chooses settings to try... (Since it will re-adapt anyway after the bushing renewal, why not let it start from already-known adaptations?) The bushings now have ~ 5K mi on them, and seem to be in the sweet spot (see, over time, 4C crashes kill the bushings, and that affects how 4C behaves, so the question is: just how badly beaten up were the bushings on Volvo's test caR when the 4C algorithms were finalized?). Anyway, after the re-cal, 4C was performing better than it ever has (...1st re-cal with fairly new LCA bushings, plus stiff sidewalls, which makes more of a diff on lightweight 17" than those heavier 18" wheels...).

IOW, 4C's adaptives seemingly had retained ancient memories of a different 'configuration' (in terms of tires/pressures/bushings/endlinks/etc), and forcing it to start over was beneficial. And since these caRs (bushings and other stuff) change (degrade, or get improvements) over time, I now see it as a mistake to try to never need a SUM re-calibration.

I just leave my headlights off when I do it, so I don't have to screw around with headlight (un-re-)aiming.

BTW: The more I dream of non-malicious 4C behavior, the easier it is to recognize it, and the more it seems like the 2nd driving cycle after a re-cal can be the best that an unhacked 4C ever behaves; after 1 round of adaptation (I shut it off for a minute or 2 after 1 extra-bumpy mile at low/moderate speeds) it's already on the right track, but it hasn't begun maladapting (and learned to torture) yet... (It will permanently lose its way -- join the dark side -- after another adaptation or 2...)
 
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