Transmission slips ‘once in a while’
Such was the case with a 2005 Dodge Dakota that rolled in to our shop equipped with 4WD, 4.7L engine, and a 545RFE transmission. Trucks like these are our bread and butter being located on the border of a big city with lots of farming and commercial operations on the other side. The customer’s complaint was “It feels like it’s slipping once in a while.”
We have a routine for our initial evaluation like everyone else: check fluid levels, scan for codes, test drive, and perform an undercar inspection. While checking fluid levels I noticed this: A new/reman PCM (Figure 1). Possibly not that it is relevant at this point, but something to make note of.
Diagnosing Electrical Signals
I’ve always had been fascinated by technology and electronics, and I can remember the first time I used a scope. It was in my high school auto-tech class, and we were being intro-duced to ignition waveforms using a Sun Engine Analyzer. I pulled my 1968 Barracuda up to this huge machine with all kinds of leads coming off of this big arm that hung over the engine bay, and everyone in the class was overwhelmed by what was going on. It was amaz-ing to me that my teacher could tell that my points (anyone remember points?) weren’t gapped properly and that I had a bad plug or wire on #3 cylinder simply by looking at the electrical signal on the scope.
If You See Something that Looks Wrong, it Very Well May Be
The subject of this article is a 2006 Hyundai Sonata that came into our shop with a no-shift complaint. It was likely in limp-in mode, so in order to get down to the cause of the problem I began with a cursory preliminary inspection.
Analyzing Clues Solves TCC Mystery
The vehicle was a 1995 Ford Ranger 2WD, equipped with a 4R44E transmission. It had originally been repaired by a local transmission shop that had removed the unit and rebuilt it in house, though we had no knowledge of what the original complaint was at the time. After their repair, it would set a P0741 (TCC stuck off), OD light flashing etc. They’d had the vehicle for quite some time but then decided to purchase a remanufactured unit from one of our distributors when repairing the rebuilt unit was unsuccessful. After installation of the remanufactured unit, the same code and symptoms returned. It was then that the vehicle was brought to our shop for diagnosis.
