R&R Tech
- Subject: Intermittent jerk at highway speeds
- Unit: 4F50N
- Vehicle Application: 2005 Ford Taurus
- Essential Reading: Rebuilder, Diagnostician, R & R
- Author: Lee Cappen
By listening to the customer, not only can we often learn what he needs but also we sometimes can pick up valuable information that helps us solve their problem. In this instance, listening to the customer helped us find an unusual problem that could have been overlooked, leading to an expensive and unnecessary repair.
The customer brought his 2005 Ford Taurus to our shop with a complaint of an intermittent jerk at highway speeds. The customer had gone through the trouble of documenting the times that this jerk appeared, the temperature at which it occurred and under what driving conditions he was feeling the intermittent condition. He also told me that another shop had recently rebuilt the transmission. I took the time to listen to him and to ask several follow-up questions that would help me correctly identify the problem. It occurred only once every couple of days.
I started my troubleshooting by scanning and found a stored P0715 code, for a turbine-speed sensor (TSS). This gave me a logical starting point. I checked all the wiring and the connector; they looked good. Next, I cleared the code and went on my first drive. Everything checked out great, and during the next two test drives the unit never set another code. I decided to wait until the next day and try it again.
At last, after a 15-mile drive I felt a jerk and the P0715 code returned. I returned to the shop and decided to pull the TSS for a closer inspection. The sensor looked and tested good, and its resistance was well within specifications. I started to wonder whether the other shop could have used an incorrect reluctor wheel for this unit. I remembered reading a bulletin produced by our tech department that told us of several instances in which AX4S and AX4N transaxles were built with an incorrect reluctor wheel. This causes the gap between the wheel and sensor to be either too large or too small.
This particular Taurus had a 4F50N installed in it, as the AX4S was not available in a 2005 Taurus. Could it be that the other shop used an incorrect reluctor wheel? I measured the depth of the reluctor wheel and, sure enough, it was out of spec for a 4F50N. This would have been an easy fix on the older-model Taurus with an AX4N or AX4S because they use the same sensor connector, but because the 4F50N uses a completely different connector the only less-costly option was for me to splice in an AX4S connector (part number 3U2Z-14S411-VBA) from an early-model Taurus. It sure made the customer a lot happier than our having to tear down the transmission and replace the reluctor wheel.
After completing the repair I took the car for several test drives with no issues. We released the car to the customer and followed up with him about a week later, and he told us that the jerk was gone and that he was very happy that we had listened to him and worked together to solve his problem. That’s what it’s all about; a happy customer and one who actually helped us help him. Always take the time to listen to your customer; you just might learn how to help solve the problem more quickly and with less expense for everyone.
Lee Cappen has been with Certified Transmission for more than 10 years. He is the head diagnostician at Certified’s location in Council Bluffs, Iowa.
