Hello everyone... the other day after driving home from work, I stopped to do some errands, and when I got back on the highway, I noticed my car was not shifting into overdrive, and my RPMs were staying up very high (around 3100 at 70 mph). Instantly assuming I had the shifting lever in wrong position, I of course checked that, and it was in the OD position.

The car shifts through all the other gears just fine and does not slip at all. What could be causing it to not go into that final gear? Is there a fuse maybe or some other electrical problem? I have only a very mediocre understanding of how automatic transmissions work so bare with me.

Thank you for any help.

 

...the first thing you need to do (after checking the OD cancel switch) is check the trans fluid and see if it is red and clean, or is there a burnt scent to it. Is there a darkness (blackness) to the fluid? get a white tissue and wipe the stick on it. does it leave a soot/ash deposit on the tissue? that would be carbon deposit from burned friction material (4th clutch). If you do NOT have any evidence of carbon, and the fluid is perfectly red and clean, then the problem could be:
OD cancel circuit malfunction
bad OD solenoid
bad wire in the OD solenoid to ecm (ground) circuit
bad speed sensor, or TPS error so that ECM does not engage 4th
etc..

you can test to see if the computer is grounding the OD solenoid with a meter in circuit at the ecm

Read more: http://www.justanswer.com/questions/mom4-wont-automatic-transmission-shift#ixzz0PHhM83O3

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