hi All, I'm going to be replacing switches & other components on my '90 964 and am wondering if I need to disconnect the battery while doing work that requires unplugging parts....ie: ICV, O2 sensor, DME etc.

Thanks much,
alanP

 

For single connectors like ISV and O2 sensors I wouldn't worry about but when you get into bigger things like the DME which requires removal of the seat, or anything fuel related. I'd rather be safe than sorry and disconnect. IMHO

 

Thanks Laker, I didn't want to take the chance of screwing up the computer if I plugged something back in wrong. Disconnecting the neg from the battery would be the ticket.

Slowly learning about these beasts...

alanP

 

There are a lot of wires under the seat and that area also tends to collect water/moisture so there is a greater chance to short something (very expensive) out. When working on anything fuel related (even when I changed the fuel filter) I don't take any chances. One of the reasons to leave the battery connected is so the DME doesn't have re-learn the engine and your driving habits, but if you are going to pull it anyway, that argument is moot.

 

If you unplug (remove) the ECU/DME you MUST disconnect the battery and preferably for 1/2 an hour before you start the work.

 

You can remove the DME without pulling the seat. Reconnecting incorrectly would be difficult (I suppose you could but the broken parts as you try to jam a square peg through a round hole should be a dead give away that something is not right).

 

Just because of the Air Bags, I always disconnect the battery if I'm doing anything electrical. The other things are important as well.