Transmission Problem

[Richard]

Thanks for accepting me into this forum. I am from Papua New Guinea.
I have a Mitsubishi Galant 4 cylinder petrol 4g93 engine with F4A42 Automatic transmission. Every time I shift into D the car moves a bit and will shift into 3rd(limp mode) If I don't accelerate and keep the speed less than 10mph it will stay in 1st gear. Reverse works fine and I can shift manually 1st and 2nd. It seems only the 1st gear works in D mode. Someone told me to change the TCU but I want to check on all possibilities first.From where I come from parts are expensive and very hard to source.

[Richard]

No replies yet, I guess I can't get any help from this site than. Might as well look around for other alternatives.

[RedGalant2k1]

Most likely the tcu, you can refer to our knowledge base for additional input also.

[oakrdrs187]

Could be internal transmission failure. How well did you keep up on your maintenance of it?

[Richard]

I bought the car from another person so will have no idea how well he maintained it. All I know is after 2 months of owning it I couldn't get any forward gears one night in a night club. I had to reverse 10km home. A mechanic friend did some work on it, he managed to get 3rd gear(limp mode) working but the reverse stopped working. Another mechanic friend did some more work and managed to get the reverse online, so now I had limp mode and reverse. Unfortunately the clutch plates on the reverse mode wore out so I stripped it down and did a overhaul. I ordered overhaul kit from Transpeed in Hongkong. Now I have reverse, 1st gear, 2nd gear working on manual drive but when on D mode only 1st and 3rd(limp mode) work. Is there anyway I can by-pass the TCU? that's if it's a TCU problem

[Richard]

I bought a new TCU and it's still not shifting. Any ideas people?

[gtx]

You did a complete overhaul? Did the solenoids check out? Valve body good?

[Richard]

Yes I did resistance check on solenoids and they checked out. The valve body has been put together as the way it was removed and with manufacturer spec(hope so). I'm suspecting the cause might be the input/output speed sensors. I did harness check on the sensors and they checked out okay, I will have to run another test using a oscilloscope to confirm. Problem is where to find an oscilloscope. Any other ideas will be very helpful around here please.