Tin whisker analysis of Toyota's electronic throttle controls

This paper aims to present the results of physical analysis that was conducted on Toyota's electronic engine control system including accelerator pedal position sensors (APPSs). The paper overviews the analyses and focuses on the discovery of tin whiskers found in the accelerator pedal assembly, which are an electrical failure concern.

Analytical techniques such as X‐ray fluorescence spectroscopy, scanning electron microscopy and energy dispersive spectroscopy are utilized to present a construction analysis of the APPS.

The use of a tin finish in the APPS is a cause for concern. Tin finishes are known to produce metal whiskers that are conductive and capable of creating unintended current leakage paths. In the analysis, a significant number of tin whiskers were found.

The methodology discussed in this paper can be implemented to inspect for tin whiskers in the APPSs.

The paper begins a construction analysis of different parts of the Toyota engine control module and APPSs and then moves on to highlight electronics design issues that can comprise the engine control system and cause unintended consequences.