CEL lit after repaired transmission
 

Had a problem with the transmission of my Honda Civic EX Coupe '96. Returning from work, engine light turned on and transmission did not work. After few minutes parked at my place, transmission worked. Very next day on my way to
work, car ran good but with the light on. Transmission failed again in front of my place of work. Took the car to my regular shop. After some testing, they said a speed sensor and a solenoid need to be replaced so I authorized it. When car was done, 5 minutes on the expressway back home, light came on again but I felt the transmission smoother than ever. Went the following morning to the shop and they reset the light again. Drove to work and light DID NOT come on but returning home it did. Also noticed that it do not switch to third/fourth (not sure which one) gear. What could this be? What needs to be done?

Thanks in advance to help me figure out this situation.

What code?

Don't know the code but I can find out

Code relates to the Torque Lockup and Main Shaft if I'm not mistaken. The weird thing is that yesterday on my way to work, the light turned itself off. No more CEL lit. Is that possible even though overdrive is not engaging?

could be your torque converter on your transmission depending if you are automatic and if you are then i would start looking for a transmission

+1

How is it possible that the CEL went off by itself?

The ecu runs test while driving if it passes the code clears. This dose not mean you do not have a problem It just did not have a problem at that time.

If it is the tork converter lock up code the ecu looks at engine rpm and input shaft rpm they should match if the torque converter is locked. If they do not it codes................. meaning the ecu is commanding the torque converter to lock but is not for one reason or another.

OK, I went to an Autozone and got a free test. Codes were 700 & 740.
Some advice is needed. Thanks!

like we said before your transmission is toast take it out and get it rebuilt or get a new one. If you want to look at the diag you can get a book at www.hondatech.info and run a search for your car. Download load the book. Run the diag it will have you test some wires replaced some solenoids and then have you replaced the transmission in the end anyway.


p0700 is a general code meaning something is wrong with your transmission. p0740 is a more in depth code meaning there is something wrong with the torque converter lock up system. It is a simple system the torque converter is unlocked during accelerations and mid load but when you are cruising it locks the torque converter directly to the motor allowing it not to slip at all. This helps with gas mileage on the highway. No power is lost in the torque converter slipping. If you get the wire diagram you will see that the ecu controls the torque coveter lock up solenoid. So the system consists of the ecu the wires running to the converter lock up solenoid the lock up solenoid and the clutch inside the torque coveter.

For the most part what I have seen is 1 crap builds up on the solenoid screen you can clean it but the code comes back due to your transmission is old and crap keeps building up on it 2 the clutch slips. It is best to just get the transmission rebuild or get a new one. To get all the crap cleaned out of the transmission and start with a fresh clutch.