Hello, New to the forum hoping for some help. This will be a little long winded unfortunately. The truck is 2001 F550 7.3 has 42,000 original miles. It has a PTO ready transmission. Have owned the truck for several years and it has run flawlessly…and it still does minus the flashing OD light which just started a few weeks ago. I purchased a autophix Ford scanner and pulled code PCM codes po715 and po717. I went in to replace the turbine speed sensor which I found to have the wrong sensor installed and not properly seated. That took a couple days to figure out It had the TSS for a non pto tranny installed in it. I replaced with the proper sensor and it was still flashing the OD light. I tried to have a friend with a shop read codes to see if it would throw a code I wasn’t reading. He has a high end snap on and a couple other scanners all which would not communicate although they will power up. I have checked the TSS connectors, output sensor and the sensor on rear end connectors including replacing rear end sensor. I then put FORScan on a laptop and it read the same codes as my other scanner just to be sure I wasn’t missing something. I tried driving truck with OD off for awhile and it will not flash? After a few minutes after pushing OD button it will flash again. Also when I shut truck down and restart no flashing until I drive it a short distance with the OD on? I have disconnected batteries overnight to clear pcm etc also cleared with scanner? Lost at this point. Any help would be greatly appreciated.

 

Your friend's high-end Snap-On scanner wouldn't communicate via the OBDII port yet your cheapie scanner is able to?

That doesn't really make sense.

-- Dave

 

You have electrical codes for the turbine speed sensor. Most of the time that is due to a wiring problem between the sensor and the PCM, not a bad sensor. Check each of the wires for continuity from end to end, short to power, and short to ground.

 

Couldn’t agree more. My 150.00 dollar Ford scanner and FORScan both read same codes?

 

From the TSS to the PCM plug? Going to need to figure out what pins at the PCM for the TSS. Thanks for the reply’s. Maybe beyond my technical level.

 

That is correct.