04 XC70 Transmission Service Required - where to start?

[abscate]

Thanks for the follow up ... how old was the battery?

[precopster]

It's all in the detail. mikeamondo is from West Virginia and FrankAZ (last poster) is from Phoenix.

There was no follow-up; just a new post from a guy with the same year of car (not even a XC70)

[FrankAZ]

Thanks for the follow up ... how old was the battery?

Hi. Sorry - yes I should have mentioned that. The battery was six years old. Six years is a very very long time in southern AZ where batteries are tortured by the heat even if they are forgiven below freezing start duties.

The peculiar thing (to me) is that the battery gave the usual outward sign of vitality: sub-second car starting. I suspect that one or more cells were damaged so that the simple old-school electro-mechanical starter still received enough current to turn the engine and initiate a fast engine start, but the reduced voltage from a battery with at least one shorted cell caused misbehaviors in the electronic systems and those became more severe as the internal resistance of the dead cell increased with increasing sulphation of the plates. Eventually the key-on voltage to the electronics was insufficient to support life, and the CAN bus errors were the first visible manifestation.

Readers in more wintery climates would likely notice cold-cranking problems before the battery degrades to the point of causing electronic issues.

I think that the CAN bus errors seen on my Volvo would not be restricted to just my brand/model/year of car and would rather be a function of any automotive electronics. The fist visible symptoms of ABS, Transmission, and other CAN bus related error codes would be as likely to occur on any vehicle, but perhaps more so on a lengthy Volvo model with the battery in the trunk on the far end of a wire gauged for normal use.

In the meantime, one week on, the Volvo is running as eager and reliably as it ever was. Except, now that my wife has enjoyed a couple of weeks using my car as her daily driver there is now talk of a new peppier car in her future.

Frank.