The primary reason is safety. If the wrench touches the chassis while removing the ground, (Negative terminal), no big deal. Do the same when removing the positive terminal while the ground wire is still connected and watch the sparks fly. If the wrench should then weld itself in place, then you have a massive short with the possibility of the battery exploding.

Dennis

----- Original Message -----
From: Jack <john.cook58@VERIZON.NET>
Date: Tuesday, September 21, 2004 9:46 pm
Subject: Q: Battery Disconnect Sequence?

> Ok, I need help.
>
> In several manuals, including a Ford Owner's manual (forgive me)
> and a
> Haynes repair manual, I've noticed that they specify that the negative
> battery cable must be removed first when disconnecting the
> battery.  Why???
>
> What possible difference can it make which terminal is
> disconnected first???
> When I first ran across this, I ignored it as a harmless error by
> someonewho didn't understand electrics, but now I find it in
> "professional"references.
>
> Help!  What am I missing?
>
> //Jack
>