The ICM is the 4-coil base mounting "plate". it tends to crack and cause a misfire - junkyard. Always clean the coil base contacts and the electrical connectors with electronics cleaner spray and make sure the ICM ground cable terminals are clean and tight. Use this to get the plug wires on the correct coil terminals and plugs.
Subscribe the car to www.alldatadiy.com and/or get GM service manuals from eBay or www.helminc.com. You WILL need the manuals, and Haynes or Chilton are far, far too generic.
Automobile(s): White Diamond '03 DHS (with DTS floor shift)
Re: 1995 SLS questions on codes
Originally Posted by jesseothon
Location & difficulty of changing ignition control module?
It's on the rear cam cover. 4 coils (visible in the picture below) are mounted on it . Unplug the 4 electrical plugs (2 on each side). Remove the mounting bolts. One is hidden on the back side and uses the Braille method. Lift it off and set it aside with the coils and plug wires still attached. Mount the new one and then swap the coils (plug wires still attached) to the new ICM in the same positions. Reinstall the 4 electrical connectors. It's that easy.