In early 2013 I have started the tedious process of collecting parts in preparation for the “nut and bolt” restoration of my low mileage 1979 450SE planned for the next 2+ years. To make my life easier, I have bought a mechanically sound, but rotten, 1978 350SE as a donor.
When dismantling the donor I have noticed that its ignition module (a.k.a EZL) casing was corroded beyond repair. Being a curious engineer, with some basic knowledge of analogue electronics, I have decided to donate the part to science in an attempt to reverse engineer the entire Bosch 0227100001B module. Curiosity was one motivating factor, OEM spare part cost at the dealership was another – at the time the module cost nearly 1000EUR!
Truth be told, these modules very rarely fail and there is no shortage of affordable second hand units on sites like eBay. So, why bother? Everybody likes a challenge! Hence, after about two years of very sporadic work on the project, the end result were two perfectly functioning prototypes, built using off-the-shelf components available at any respectable electronic parts supplier for under 50EUR in total.