Darwin Upton
Darwin Upton
Not What It Seems. Illusions
You have undoubtedly heard the phrase “Everything is not always as it seems”? That can hold true to many things in life. Harry Houdini made a lot of money creating illusions and misconceptions. And the field of fixing transmissions is an all too common problem area for misconceptions, that can cause you to lose money. […]

Taking a Bite Out of the Drac
No, not the nocturnal dude with the cape and fangs. We’ll be looking at the “Digital Ratio Adapter Controller” (DRAC). That’s a mouthful, so we’ll be saying DRAC from now on. Another name sometimes used in wiring schematics is “Vehicle Speed Buffer.” It was used on most GM vans and light-duty trucks built from 1988 […]

Being Neutral, the Allison NSBU Switch
What we’ve known as the Neutral Safety Switch has changed over the years and has had various names such as the Park Neutral Position Switch, Internal Mode Switch, Range Sensor, and a host of others. Some are on the outside of the unit, some are on the inside, either by itself, or it may be […]

Rise of the MAF
From the beginning of the electronic era, we’ve been chasing inputs and outputs as root causes for failures. In this case, we’ll talk about how no line rise can cause the 3-4 clutches to burn in a 4L60E. Here’s the customer complaint: The driver gets in his truck, gets ready to take off, and puts […]