1998 v70 Battery Disconnect Problems ?

[MrAl]

Hi,

From what i have read around the web, there might be problems with some systems if the battery is disconnected, then reconnected.

Sooner or later we may have to do this, or maybe the battery might go dead. What do we do then?

Does anyone know what systems will be affected on this car ?

Thanks again

[E Showell]

The radio, for one. You'll need the radio code every time you disconnect the battery.

[obayha]

I have disconnected the battery on my old '98 many many times and never had a problem, except the radio code. Just disconnected it on my '99 this weekend for a welding fun time and started it this morning and drove 50 miles to work, no problem.
I have heard of the system having to relearn by starting out slow, going through gears, and things like that, but never have had to do it.
Shane

[abscate]

Most cars from the 1990s on use some kind of electronic mapping to determine spark advance and fuel injection amounts. These aren't fixed in stone, the car brain actually adapts the map to conditions and driving habits. Disconnecting the battery wipes the map out, at which point the brain uses a default set of parameters for a few hundred miles while it writes a new map.

If you don't drive like NJ, you might not even notice this process.

( sorry about that dig, but my recent I287 was 85 in the slow lane? Seriously)

The electronic approach is cleaner, more efficient, more powerful, longer lived, and probably cheaper to both own and operate than our Parents' Oldsmobile Delta 88

[misha]

Most of members here didn't had problems at all after disconnecting battery.Some of members reported that their cars "learned bad things" after ecu is being reset by removing battery cables.
Volvo instruction manual says that few problems can occur:
-rich or lean running
-stalling,hesitation or stumbling
-harsh or poor shifting(automatic transmission)

Affected vehicles are the ones with Motronic 4.3 & 4.4 management.Personnally...i had always the same problem which occurs after a few days and that's rich conditon.In volvo instruction manual,there is a relearning procedure which can be performed after battery is being disconnected.

[abscate]

Quick addition

If you are contemplating removing seats or anything involving airbags, start a thread here about it and research before starting work.

You can easily end up Paying a 100 use dealer tax if you foul up the air bag or ABS systems.

[MrAl]

Hi,

So i guess what you all are saying is that there could be a time after the disconnect where the car doesnt run quite the same.
Radio code shouldnt be a problem.

Thanks to all who replied

[misha]

Yes...that time is called driving cycle and it needs to be completed to make eventual symptoms disappear.In other words....ecu needs some time to complete injection map gathering new parameters from various engine sensors.

[MrAl]

Hello again,

Oh yes, the ever problematic Drive Cycle. That's nuts too

But what else bothered me is that one site said that the key should be turned on to position 2 i think before reconnecting the battery.
Any idea what that is all about?

[misha]

I would not do that.It is required for newer models for various reasons.