From digest.v7.n1230 Tue Mar 3 11:04:41 1998
From: Bill Wessale <wessale_at_iwl.net>
Date: Tue, 03 Mar 1998 07:24:02 -0600
Subject: Opening ECU on 535is
I assume you've already removed the ECU from the car. If not, it's
located above the glove compartment. It hides behind a
decorative plastic cover held on by a "rubber band" that stretches
across the top. After taking off the plastic cover, just remove the two
bolts that hold the ECU up against the underside of the dash. Depress
the clip that holds the cable connector onto the ECU and wiggle the
Once you have it out of the car, you'll see that the metal cover is held
on by about 8 tabs. Just pry these tabs up and pull the metal cover
You will then see two boards stacked on top of each other. Pry the
boards apart on the end that has two plastic posts between the boards --
each post will snap apart. Then at the other end, depress the plastic
tabs that lock into the board from the under side, and wiggle the board
back off the bracket that it sits on.
Open the two boards -- like you would a book -- and you will see the
PROM chip. It's the only chip that sits in a socket instead of being
soldered onto the board.
Count the pins, reassemble and install and you're back on the road.
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