I finally got time to install my tranny temp gauge in the dash of my 1988 Suburban. I noticed under the steering column a little box, it has cooling fins on it and I wonder what it is. It looks like it has been messed with before because it mounts to a clip like thing and the plastic on the box is broken for the mount. I tried to find out what it is in the chilton manual and it just does not have enough detail, sounds like it might be the Engine Control Module ??? Anyway, now I am a little worried because the chiltons manual says not to restore the power to the module when the ignition switch is on because it can cause severe damage to the module. Well I had the switch on because I needed to move the auto trans shifter to get room to reinstall the dash. I forgot to turn it off when I reconnectd the negative battery cable. I wonder where the ECM is, is it the box under the dash ??? How can I tell if the ECM is damaged now ????