I drive a 2002 lancer Es. She is all stock. 4 speed automatic. The fluid looks pretty full as stupid is that sounds. After a drive is a bit spotty on the dipstick around the full mark. Well here's the deal. The tranny shifts fine smooth right into gear. Then at random times the car will jump and just be in 3rd. This happens anytime any speeds. When on the highway doing 70+ mph will downshift into 3rd all by its self. If I place the car in neutral while doing 65mph or so and shut it off. The car will kinda jump a little like its a stick. Once I start it will be okay again for a random time. When this happens If I put the car in park from a stop will be hard on it. Same thing from drive to 2nd. Does have check engine on. I have the codes. Will put them hear as soon as I can. What could this be? Sorry first time posting.

 

I will put money on input OR output shaft speed sensor or both. These sensors are what tells the ecu what both halves of the tranny are doing (ie the side that is connected to the engine and the side that is connected to the wheels), this along with TPS is how the vehicle can determine the best time to shift the transmission.

 

This is the fault code I received. Does this mean the sensor is the issue? Or something more as in short in sensor wiring? I get what it says. But I once had a similar issue with an injector checked all wiring turned out it was just the injector. I just recently acquired this car this issue wasn't mentioned in the purchase.

 

03Lances wanted to also thank you for the quick reply.

 

No problem. I would check the wiring first to be sure its not just loose or frayed wire etc. If the wiring looks fine then your sensor needs replaced here is where it is located:

 

It's the sensor. I had the same issue, the part fixed it.

Be sure to disconnect the battery and reconnect after the installation.

 

Okay I appreciate the responses very much. I'll get the new input Shaft speed sensor. Once installed ill reaville the result. Thanks.

 

I was looking around the fusebox under the hood on the drivers side. Previous owners or so did something weird with all the wires going into the fuse box. U can see where Random fuses are no longer in place and are wired looks to be direct. The tranny fuse appears to be in the proper location. Anywho I was looking through these and as I was doing so battery was disconnected I checked wires that have been customized didn't see any issues with wires. Also I don't know how they should be wired. But they don't have any cuts,breaks or damage to them. I swapped out the horn fuse with the a/t fuse. Hooks the battery back up and started it. Check engine light is off. I have restart before and service light always appears immediately. Which this time it didn't. I sat there with t running for a few minutes. Drive around light never returned after about fives minutes. But the tranny seems to slip into 3rd maybe alittle into 4th. Light again never returned as of now. When the light is on and randomly only has the issues listed in original posting the transmission would shift perfectly through all gears. Safe mode or what not would happen once twice if more at some points but never slipped. Fluid looks to be possibly a bit full. Not sure why but hard to read dipstick hear. Any suggestions?

 

Was a short at the underhood fuse box. Wire routes to the fusebox for the transmission. Was shorting out at times. Explains why she went into safe mode at times. Bumping around would short it out. Want to thank everyone for the advice.