blinking O/D light
 

Have 2001 Protege w/2.0 and auto trans. 120,000 on odometer . Shifts fine, goes in/out of overdrive ok. No rhyum/reason why O/D light starts to blink. At start of drive or mid of trip to store
Have blinking O/D light . Been told has to do w/tranny. Haven't found many threads on subject. What is cause? Where can I find a code reader for tranny?
What's a DIYer to do?????

update on post ...... drained tranny fluid from pan. refill w/ fresh .Day 3 and no recurring O/D light blinking!!!

Protege 1999 O/D blinks and turn on
 

I have a 1999 Protege LX with Auto Trans. it has 121k miles. When the car is cold, I wanna start the car and when the gear is D the car has a shift and the O/D off light blinks .... I went to a master mechanic and he scanned the car , he said there is no code and fault and everything is fine , he drove and he said there is no worry , he just said that maybe the O/D off button has a problem , and when he was checking the car ,the car was warm and I just have hard shift and jump when the car is cold .... is it possible that is for TPS , Converter , speedometer sensor ? I just have the problem when the car is cold and I put in D and wanna drive ...

When was it the last time you had the transmission serviced? I.E changed the fluid and the filter?

I changed the transmission oil and service 5 months ago , I have this problem just when the car is cold and when I put gear on D and wanna drive I have hard shift but when the car is warm and on the highway everything looks fine, even the mechanic drove it and he said it works well .... TPS , speedometer sensor , and what about O/D off button , he said maybe the button has a problem and doesn`t work well , if he button doesn`t work well , could it cause the shift ?

Well, yes a bad electrical connection at the button could cause a shift problem. The computer decides the shift points depending on whether you are in OD mode or not.A bad contact could appear to the computer as if you were toggling the mode.
There is also a transmission range sensor on the transmission. It also could be involved with an electrical problem.
First make sure these things are correctly connected. Disconnect them and inspect them for anything obvious, like corrosion, blank wires etc. and put them back together.

Thanks for your comments and help , I am student and I don`t wanna pay too much money for service , the car drives well and every thing is fine , even the mechanic drove and test it , the problem is that when the car is cold and in the morning when I wanna start the car I have a hard shift and O/D blinks , so what do you suggest for the first test and check ? Do you agree with the mechanic to check the O/D button ? or connections to the transmission ? the engine light is off and I searched many resources that show the jump and shift when the car is cold , I mean I put the gear on D and then I have shift for the first move .

It's your neutral safety switch. It's on your transmission. Easy to change. 99% of the time the contact's get worn and cause the car to think it's in park or neutral while driving,but since your moving it trigger's the OD light.

Thanks, Orville! I didn't think of this. i will include it in the "Unofficial user's Guide".

I have a 1999 Mazda Protege with 124 K miles on it. It drives well, the transmission is smooth, but when the car is cold and I start and turn it on the o/d off light begins to flash and it starts shifting weirdly. I think the transmission does`t engage and the move is kind of hard , I can't accelerate and I have to pull over and turn it off and start it up again. when I turn the car off and start it again , no more flashing and the car drives well. it seems to be fine and every think world perfect and no OD light until the next episode. The check engine light never goes off. My friend told me you need to change the transmission oil and the last one has a bad quality , the bad oil can cause the OD light ? speed sensor or Torque converter ? the OD button works and no fault …. Any idea ? I changed the transmission oil and filter 9000 milage ago …