The general trend for the mounting location of powertrain electronics reflects a migration from the traditional passenger and engine compartments to on the engine and transmission. Because of high level for accurate and secure working of electronic control units (ECU), producers established appropriate criteria which must be satisfied during different testing procedures. One criteria is allowed vibration level. In this paper, measurement technique and analysis of vibration level of ECU for passenger car equipped with an up to date diesel engine, is shown. Existing universal measurement equipment is used. For analysis and signal processing, according to methodology and criteria by ECU producer, appropriate software is developed. Also, in this paper, some testing results are given. It is shown, that in prototype design, this way for getting preliminary results of ECU vibration levels is very reliable, fast and not too much expansive.