Solving temperature-related, no-code intermittent failures can be a frustrating experience for the diagnostic technician because the exact level of heat or cold needed to trigger the failure is often hard to duplicate. It's also important to keep in mind that all electronic vehicle components are exposed to temperature extremes and thus are vulnerable to temperature-related failures.

Early in my electronics diagnostics career I had to deal with a 1980s-model Nissan pickup that wouldn't start when ambient air temperatures dipped below 20° F. One shop had already replaced the engine coolant temperature sensor in an effort to solve the problem and, because no data stream information was available on that model of Nissan, I was left with pin-testing individual sensors in freezing temperatures. Unfortunately, the vehicle would start as soon as the ambient air temperature rose above 20° F, so the diagnostic process would be put on hold until colder weather prevailed. Why 20° F had become the threshold temperature needed to trigger the failure, I can't say because I could rarely duplicate the required temperature condition. In this case, the temperature-related failure might have been caused by a faulty winding in an ignition coil or solder joint in the circuit board of a computer, ignition module or air flow sensor.

The Stalling Nissan Quest
This month, I'll present two case studies that illustrate how data collection a...