Hotline Archive Helps Fix F-250
Occasionally you run across one of those extremely unusual complaints, one that no one ever remembers hearing. Recently, I had just such a call.
The vehicle was a 1997 F-250 7.3L Power Stroke diesel with an E4OD transmission. The complaint was no torque converter clutch (TCC) lockup, and the technician said there was never a code stored in the powertrain control module (PCM).
This vehicle ran flawlessly. The transmission had been rebuilt 50,000 miles prior to this, and again recently, to try to cure the TCC concern. The tech had tried clearing codes and rechecking operation, in case it was a scanner issue. The PCM had been replaced twice, and the solenoid pack and subharness had been replaced as well. He also verified that the stop lamps worked and that the correct bulbs were installed.
Then, for some reason, my "senior moment" started to subside. Something sounded familiar, so I logged onto Identifix Direct-Hit and searched - using "Keyword TCC" for "Models w/same engine package +/- two years." It returned eight Hotline Archives. Amazingly, the second one, authored in August 2005 by - guess who - me (no wonder it sounded familiar) on another 1997 model, had the identical symptom.
On the sixth call, I had asked the tech the elevation of his shop, and he said it was approximately 1,000 feet. Next, I had him check the manifold absolute pressure (MAP) sensor frequency. This was reported to be 111.7 Hz, which confirmed his elevation. When I asked him to check the voltage of his barometric pressure (BARO) sensor while backprobing the dark blue/light green wire for between 4.4 and 4.6 volts at that elevation, the reading turned out to be 0.16 volts. It is likely that only the space shuttle could get a reading that low, so the sensor was replaced.
And so, with the help of that forgotten Hotline Archive from nearly three years ago, the current vehicle also now shifts perfectly. I am proof that no one can remember everything!
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