I have posted a bit about this on another thread but I really could use some help on this so giving it a shot here. I bought this truck for what I think was a good deal, with knowledge that it had a blinking overdrive light and would occasionally shift out of overdrive. The OFF light has been absolutely random at times and has also gone into a steady pattern of on/off. The truck has right at 100k on it, original paint and interior in fantastic shape, under the hood is immaculate. It does have an ATS built transmission and Commander box under the dash. There may be more mods but I don't know how to recognize them.
So far I have pulled the gear selector apart looking for the chafed wire issue, to no avail. I downloaded FORscan, bought the recommended bluetooth dongel and am getting no codes. I did have a low voltage/start problem that needed a couple of new batteries, had hopes that might of been a factor but no.
So, the problem continues, no codes ever. HELP

 

When you find out what it is make sure you post the answer . Most times its the Speed sensor on the rear axle . Could also be a broken wire leading to it . Look at memory codes . PO500

 

No codes. I'll check the VSS. Anybody here know it there is a test/ohm reading..etc, to test the VSS?

 

Check out this thread. Maybe it'll help you.

https://www.ford-trucks.com/forums/1...ese-codes.html

 

Thanks! I read part of it and will take some time this evening. The baffling thing is that FORscan shows no codes at all.

 

There should be one error code for battery. If not then you might not have chosen the right connection type in your app.

 

Soon after I got my truck in 06 I started having trans trouble . Ford told me a VSS no joy . The problem was intermittent. Ford then said I needed a new PSOM so I ordered a used dash panel . Before it arrived I hooked up my scanner & it turned out ever time I hit a bump in the road my spedo & scanner stopped registering speed . I looked at the rear wiring again. There was a repair to one of the wires . I cut it out and replaced the connection . While inspecting the other wire I found a soft spot that you could stretch the plastic. Turned out the copper inside was completely broken apart but would be OK till I hit a bump and the wire would bounce & loose the connection inside . I repaired that wire too. After that I didn't have the problem again till it got warm this spring ( rebuilt modded trans 5-6 years ago) . I replaced the wiring & plug to the VSS and was good for a while . Problem returned so I replaced the VSS with the old one I had from 06. Problem went away , for a while . Next I looked for a motorcraft sensor , had to settle for a NAPA . Problem went away again , for a while . I didn't replace the PSOM yet . By now the problem was totally random . Sometimes a restart would help .

My windshield has been leaking for a while so I started thinking about the PCM & the PSOM again. ( I am soon going to replace the cab and almost all of the body parts) . The baffling part is it seems to be temp related . When it got colder the problem went away . ( Till one warm day . Mornings it was always fine , just in the evening on my way home from work )One day on the way home I smacked the dash while it was acting up & it went away . Cold weather returned & the problem is gone .I suspect water from the leak got to the PSOM and has an intermediate or corroded connection issue . Through all of this the speedo has continued to work . The only time it didn't was when I had a broken wire .

Since I fix cars for a living I don't have much time for mine . As I sit here typing I am still not loaded with confidence , but I keep doing one thing at a time & will keep doing it till the dang thing is fixed , or I will die of old age .

 

Still wrestling with this. I have the full version of FORscan, what connection should I be using?

 

The issue seems to be fairly random on my truck as well. I drove it a couple of times and it acted up quite a bit. Drove it yesterday for about 35 minutes and thought maybe it was getting better right before the light started fairly rapidly blinking on and off and shifting in and out of overdrive.

 

There's codes stored if the OD light is blinking, maybe your PCM isn't program for OBD2 reading that why you can't communicate with the PCM.

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It's reading the modules that I have programed into it and shows a successful connection. Of course, I could have something wrong, I am a bit of a novice with the more advanced code reading program.

 

Use the communication in the profile
SAE J1850-PWM