overdrive light flashing - Ford Powerstroke Diesel Forum

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post #1 of 8 Old 03-18-2008, 03:24 PM Thread Starter
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overdrive light flashing

The other day on the interstate the tachometer started to vibrate a little and drop some but I did not notice any loss of power and then the overdrive light started to flash and will not stop even after shuting down and restarting.
I have noticed a slight difference in shifting (not as smooth) and when parked and running I tried unplugging the tachometer sensor and the OD light stops flashing but when I drive about 100 feet with it unplugged the OD light began to flash again.
Could the tach sensor be bad?
Thanks in advance
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post #2 of 8 Old 03-19-2008, 03:29 PM
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Is the ABS light on too? When the OD off light flashes, that means the transmission is in "Limp mode". The computer is not getting a signal from one of the sensors (usually the tach sensor or ABS sensor), so it goes into limp mode which firms up the shifts quite a bit so as not to cause harm to the transmission. Since you noticed some weird tach symptoms, I would say the tach sensor is bad. In my case, the ABS light was on too and that meant the ABS sensor on the rear axle was bad. $12 later, problem solved.

Derek
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post #3 of 8 Old 03-19-2008, 06:03 PM
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Youve prob thrown a code, go somewhere and have them look to see what is says, then fix it....

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post #4 of 8 Old 03-19-2008, 06:19 PM
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when mine did the same thing at 120K i just drove it, i knew what the code would be, a good friend of mine is a ford mechanic at the dealer and he said drive it, itll go out either way and well i got to 205K b4 i replaced it and the trans had some left at 205K too

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post #5 of 8 Old 03-19-2008, 06:23 PM
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mine has done that once and it shifted from 3 to 4 at a low rpm when it should have stayed in 4th. it done that till i shut her down then everything was fine. not trying to jack the thread just had a similar thing happen and have not had an answer for it

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post #6 of 8 Old 05-12-2008, 02:46 PM
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Ive got almost the same symtoms. Where is the RPM sensor located? Did you get yours fixed?

-Chad
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post #7 of 8 Old 05-12-2008, 03:31 PM Thread Starter
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Try a new TPS

I am not sure if I solved the problem but it has been driving alot better. I bought a Throttle Postion Sensor from Autozone for $28. I hooked it up just like the old one and I had to find the right postion where the O/D light didn't blink. The light has stopped blinking and it shifts much easier although I am not sure at what RPM it shoud be shifting at, right now it is around 2000.
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post #8 of 8 Old 05-16-2008, 08:04 PM
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Have you tried the abs sensor on the rear end??? I have had a few of these with the little flasher and it has always been the abs sensor.
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