Transmission Control Unit

I think ive posted this subject on here before, but here it goes again. i have a 91 accord lx, and recently it has been running strange. On certain occasions like today the (S) light is on on the dash, but the button isnt engaged. What is wrong with this thing? Its acceleration is horrible, and it wont speed up much past 50...ive been told it is the TCU, but im not very farmiliar with that part, so any advice is wanted.

Its your TCU. When the "S" light is on the tranny is in safemode, 1st & 3rd gears only and you have to shift manually to get into 1st gear. I just replaced mine on my 90 accord. Buy a rebuilt one and make sure the numbers match. i bought mine on ebay for $225.

how hard is it to install, cuz im not to farmiliar with the transmission. And where does it go?

Very easy to install. Its located in passengerside floorboard (angled part closest to engine), pull carpet back loosen 4 screws and pull panel out, Tcu is on the right and is held in place by 3 - 10mm bolts and will have a number on it that goes something like 28100-PXO-A03-M1, just make sure you get a replacement that has the same number. I may have one that fits your car, PM me.

thanks for the input jary!

i'm not sure that is correct

it means that theres some sort of problem with transmission to be diagnosed - it doesnt nessecerily mean that TCU needs to be replaced.

I am having the same problems with my 91 accord. The speed omoter cuts in and out also, is that related. I have found if I disconnect the battery for 30 minutes to an hour it resets the computer and it shifts fine for a few days but it progresses bact to being stuck in either 1st and 3rd or 1st and 4th. does this sound like the same problem? Is there any way to test the TCU before buying a new one?

yea i didnt mention that my spedometer cuts out too, for a few seconds then comes back. So i guess we have the same problem...

is the tcu. been there, done that. around 75 dollars used. dont pay more than 80 dollars.

do not replace any parts without properly diagnosing what is wrong. u said u were told it was the TCU did a shop diagnose it ???.it is easy for people to say replace this , replace that when they are using other's people money ,,now it could be that u might indeed need a TCU but diagnose first to make sure that way u will spend your money once and properly .............pull out what code the TCU has and post it here ...

I also have had similar problems as above when I first bought my accord.  I changed the tranny fluid and it got better.  There was also a car alarm that was partially removed so I finished removing it.  Today I started having problems again and it has been raining all day so I figure I might have bad ground issues.  The spedometer is not working and after a couple minutes of driving the "S" light comes on flashing.  Does this flashing "S" light mean something specific?  I don't really want to take it to a mechanic for a code reading for $80 if I can just buy a "tcu" on ebay for $80.  Is there a way I can read the code myself?

I also found that a couple minutes after the "S" light comes on flashing, the check engine light comes on.  I also just put a new cv shaft in a couple days ago on the passenger side.  when I put it in I didn't lock the shaft all the way into the tranny and drove about 2 miles and the shaft slipped out of the tranny.  I towed the car back home and put the shaft in properly and everything seemed to be ok until yesterday.  The transmission seems to be shifting smooth and going into all the gears properly but the "S" light flashes on the dash, the check engine light comes on, the spedometer doesn't work or odometer for that matter, and the cruise does not work.

I was looking thruogh the forum and think I found what I needed.  Sounds like it's the VSS.