Truth can be stranger than fiction. Recently, a regular long haul, over the road customer came in with a ’97 Freightliner and described a concern of “The trailer lights are acting goofy”.
The powertrain control module (PCM), which controls virtually every function of the engine and automatic transmission, depends upon an input signal from the TPS (among other things) to calculate fuel delivery and ignition timing strategy.
Engines have become very reliable in recent years, many reaching over 200,000 miles without major issues. As technicians, we replace a lot more ignition coils than timing chains.
While Toyota and Lexus have always been known as relatively reliable vehicles, they still suffer from ignition coil failures like any other manufacturer.