The idle control unit is it the compartment at the rear of engine compartment. It is a black box a little bigger than a pack of cigarettes.
The PC (printed circuit ) board is inside. As to whether the job is DIYer approved its hard to say. You can do a lot wrong resoldering the board. If you overheat the chip its history. If you aren't delicate enough you may connect a number of circuits into one joint. This will let the smoke out (bg).
Owner 24 bay BSC
Bosch Master, ASE master L1
26 years MB technician
[This message has been edited by stevebfl (edited 04-21-2000).]