A year or so ago I had opportunity to talk with an engineer at MSD, a manufacturer of high performance ignition systems. We were talking about diagnosing electrical problems, and he mentioned that one of the hardest electrical malfunctions he had to diagnose involved heat-shrink butt connectors.
A race car builder was having trouble with intermittent electrical/electronic malfunction on his race cars. The MSD engineer was called on to figure out the source of the problems. Long story shot, he eventually traced the problem to corrosion inside sealed heat-shrink butt connectors the car builder used to connect wires on the race cars.
The thing that drove the engineer daffy was why the moisture-related corrosion was occurring INSIDE the supposedly sealed butt connectors. He finally figured out the source of the moisture inside the sealed connectors when he spent a couple hours watching one of the company’s race cars being wired. He noticed that the worker was holding each butt connector between his lips while he used the fingers of both hands to twist the strands of copper wiring before he installed the butt connector. The worker’s breath was introducing moisture into the connector BEFORE it was heat-sealed.
Mystery solved.
