Battery swap - now my odometer is freaking out!

[Rowag]

Hi guys. RennTech is the reason we purchased a Boxster (thanks to everybody!) And the tips (particularly Tool Pants') have been invaluable. I'm hoping that somebody can come through once again...

Our '98 Boxster had a battery dropped into it a few years ago, and it was starting to go reach its end-of-life with slow starts, etc. So I run on down to the local Battery Source store, and they had one that fit fine and had good CCA, etc.

They disconnect the old, and hook up the new. Somewhere during the process a second guy hooks something up to the cigarette lighter -- a trickle charger I assume so the radio and other electronics won't lose settings.

Once the new one is in the car starts up great and strong, except that now the odometer is freaked out. It (and the speedo) are set to km/h instead of mph, and it's reading "999999". So I flip it back to mph by holding the clock adjuster to the left, and now it reads "599999".

As much as I would love to own this thing until it has a half-a-million miles on it, it really only has ~22.3k on it. I've got a DMV records, etc. to back that up, and even a mileage reading from a tire shop the day before, but what I need to know is how does this get changed back? From what I've read here it sounds like the dealer can program an older Boxster's odometer with the PST2, but I'm not sure. Is it likely that I got lucky and perhaps just blew a fuse that caused this?

Thanks for reading. I obviously want to get this corrected ASAP -- the low mileage is a huge part of the resale value of this car, so if I have to spend the $$$ to fix it I'd rather get it corrected now while my proof-of-mileage is fresh.

Edited December 10, 2006 by Rowag

[Tool Pants]

Bet it looks like this....

[Rowag]

Bet it looks like this....

Thanks Tool Pants -- you got it. Any ideas? Or at least a hypothesis of what happened?

[Tool Pants]

Try this. Disconnect the negative cable with the key in the ignition. Then turn key to position 1, and then turn key to off position. Then hook up negative cable.

[Rowag]

Try this. Disconnect the negative cable with the key in the ignition. Then turn key to position 1, and then turn key to off position. Then hook up negative cable.

:notworthy: :notworthy: :notworthy: :notworthy: :notworthy: :notworthy: :notworthy:

That did it!! You've officially knocked 577,701 miles off of our Boxster, which I think monetarily speaking equates to about $162,328 or so. I think I definitely owe you a beer or 12.

We've put about 20 miles on the car since the fiasco (it's reading 22,298 at the moment), and it definitely has those logged. If you don't mind answering this question: what do you think happened? Is mileage stored in the ECU, and the odometer just got freaked out because it had a charge (from second guy's trickle charger) while the main battery was disconnected? I'm rather curious.

By the way, the Boxster's battery connection cables are SERIOUSLY tough. I can't help but think that in other lesser cars at 8 years old the crimped ends would be fraying, needing to be replaced, etc.

[Tool Pants]

It has nothing to do with what was stuck in the lighter. The guys that replaced your battery did nothing wrong.

Sometimes it just happens when the battery is disconnected, then reconnected. At our work on cars days over the years we have disconnected 100s plus batteries on various Boxsters. No problem. Then about 2 years ago the 999,999 deal happened after we pulled the battery on Patrick's car. First time I have seen in person this so I took pictures. Did the "fix" and the display went back to normal.

I have no clue why it happens sometimes or why the fix works.

The mileage is stored in the instrument cluster, not the ECU.