trwpaper

I have a 1991 Automatic Transmission Honda Accord with 210,000 miles that has been working very well for me over the last 7 years that I have owned it. I treat it well, drive it cautiously, change the oil regularly, and want it to stick around for me in the future. For the last two summers, the car would occasionally not start when it was very hot out. After several searches online in forums, reading peoples' responses on their similar situations with similar year cars, and failed attempts of spending money for mechanics to give me corrective solutions I finally diagnosed the problem myself. I purchased a new Fuel Pump Relay (also known as a Main Relay, and several other names) from the dealership after receiving several blown ones from junk yards. I replaced the relay, which is located under the driver's side dashboard, and the car has worked wonderfully since then.
Over the last few weeks, randomly and occasionally, mostly during the first few minutes when I start the car and let it warm up in the morning and sometimes when I am driving it, the Sport Mode light on the instrument panel will light up. The light will sometimes be on when I start the car and other times not be on when I start the car. Sometimes when I start the car, if I am sitting in the car and waiting for it to warm up and the sport light to shut off, the light will flicker back and forth from being on and off and whenever it switches there is a clicking noise coming from it sounds inside the transmission shifting console. Basically the clicking noise is coming from under the transmission shifter between the seats. Usually if I wait long enough, around 5 or more minutes after I start it, the flicking on and off will stop and the Sport Mode light will remain off, so I feel safe to drive the car. On top of this issue, a couple times when I have been driving the car, the light has flicked on, and the car down shifts a gear, because every time the light has turned on I was driving around 50 MPH-ish and it went from 4th/overdrive down to 3rd gear (I have an automatic please remember). After around 30 seconds and sometimes over a minute of continuing driving at 50 MPH at higher RPMs, the light will shut off and the car will shift back into its higher gear and drive normally again.
I have been doing several searches on this topic online and just wanted to get some more opinions before I purchased a part. According to several resources, the car is shifting into a "limp mode". This means it will only remain in 3rd gear, and most people say that it should immediately be brought to a transmission mechanic to be checked out, but I'm in college and money is hard to come by, so I'm hoping I can find a way to fix it myself. Some people say to check the throttle and vehicle speed sensors since they signal to the main computer as an indication of throttle and governor pressure and in turn the computer will command a given shift solenoid to do an up shift, downshift, lock-up or etc. type of response. Other people have said that this is a TCU problem and that I need to replace it soon.
Does anyone have similar experience with these types of symptoms? Please help me out and any advice will be greatly appreciated. Also if I do need to get a new TCU, what resources are available to purchase a cheap one for my car?
Thanks.

Mr Yamada

It is common that when the S light comes on the Trans Control Unit will store a fault code.

You will be able to retrieve the fault code by jumpering the blue 2 pin service connector then turn on the key and watch the S light for a flash code.

I would not recommend that you have the transmission taken apart, as the usual cause of an 'S' light is an electrical problem, not an internal failure of the transmission.

HennessyLane

LOL to much to read but i have the samething go on with my 91 accord it my trans computer water got in it from wet shoes it start of in 3rd sometimes and sometimes it will jump to 3rd went im in other gears.
thing about getting a 93 trans in computer in change in out.

hondadude

I think that Mr Yamada gave you very good advice.

Jumper the BLUE 2 pin connector at the top of the pasenger side kick panel; turn on the key and see if there is a trans code stored. [count the 'S' light flashes]

This is the first step to finding out what will fix the problem.

Or you can just get a bank loan and start throwing part$ at the problem.

Your choice

trwpaper

I have just purchased a new TCU for the computer. One site mentioned to have the speed sensors and solenoids checked before putting the new TCU in. Is this true? and if so how do I go about doing that?

michaelcherry59

I Have a 91 accord an my shift light is staying on, any ideals as too what this could mean, or any advice i need to pass on to my tech I'd hoped someone could lead me to a short cut thanks for any help you can give me,, michaelcherry59@yah00. com

brownje000

Hello Im having the same problem with my 91 lx honda accord I have 254,000 miles on it except my speedometor sometimes dosen't work. I took it to the shop and the person said its one the two sensors Im just going to replace both because im pretty sure the other sensor that is good now will go out later.

takemoney

I also have a 1991 Honda Accord Ex 2.2l A/T with about 140000mi on it.
About a month ago my speedometer stopped working, and thereafter the S light was always blinking. I didn't think much of it, I thought heck who needs a speed sensor, the code on the S light is probably going to be something about you have a failed speed sensor so I didn't bother checking the code. Now I'm not sure how much the transmissions operation relies on the speed sensor properly functioning, and I'm not really sure what happened next, but during the next three weeks, the condition of the transmission steadily deterioated. First there was a low high pitched squealing between frist and second and it would drop off, once you got into third. Then that escalated into a louder semi-grinding noise. At which point I was going to take it into the shop, but was reluctant to pay $100 for them to tell me what I already assumed was happening, that the tranny was [freak]ed. Then I kept driving it of course it steadily got worse...slipping gears, etc until finally today the little bastard wouldn't mate anymore, and it died while driving down the road on the way to a delivery of all things haha. I STILL HAVE REVERSE THOUGH.
Now obviously the tranny is [freak]ed now, more of what I want to know is, do you think it was preventable? Would the lack of a functioning speed sensor destroy a transmission? or was it inevitable?
Also I don't know whether there are any good guides or tips anyone has on doing a tranny swap?
I've already pulled another tranny from a local junkyard.
If you could help me out I would appreciate it.
Thanks.

hbk6a99

I am going through the same problem with the Sport Light. I took it this morning to my mechanic shop and one of his guys didn't even look and already assumed it was the transmission but the owner of the shop told me that he would look at it today and hopefully I hear it is the TCU and not the transmission.

nappysol

Mr Yamada is right on point pull the code(s) before you start throwing parts at it. As I stated in another post the same thing happened to me on my 91 DX with 256xxx. The first thing I did BEFORE I started to ask questions was to pull the code. The only code stored was 17...VSS. I replaced and no problems since. My local Honda dealer wanted $157 for sensor and O'Reilly sold me one for $82. It took me approx 15 minutes to install.

WebDawg

listen its the vss the speed sensor or the TCU usually id try the VSS aka speed sensor first. get it on ebay. I did worked great.

WebDawg

its alot less on ebay and works great

mazjanjua

I have 1991 ex honda accord 4 drs car,some time it does not start,mechanic tune up,problem remain same,mechanic changed all distributer with coil,a few days it was good then a problem add-during driving driving turn off,mechanic changed main relay,both problems are still there.
If the ignition time engine light turn off then it start or with the left foot hit side 2 time on board then engine light turn off and start.
During driving push accelerator it turn off.
Some body advice me what i should do?

When it is runing all mechanics says no problem in car?...............

craiger28

I had the same problem and jumped the blue connector, got the code from the "S" light blinking and replaced the TCU with a good used one form the salvage yard with the same part number. After I replced the TCU it worked, and shifted fine.

John Bennett

My 1991 Accord experienced similar problems. I replaced the bad components in my Transmission Control Unit. All is well now.

Here is a web page I made describing how to fix the TCU...

http://people.consolidated.net/etrid...ordtcufix.html

Hope this helps!

tina harper

I took my son's 91 accord for a safety inspection the other day and when we picked it up my son said that it was acting funny just pulling off the lot. all was fine before the inspection. now the s light comes on and it will not shift into gear after starting until you put the key in the slot on the gear shifter and then put it in neutral before starting the engine. it acts as if it is in a lower gear upon take off as it is very sluggish.
I am wondering and I am going to check the passenger side of the car to see if it looks as if the carpet had been pulled back to the unit under. could there have been a switch of a bad unit for our working unit? seems a bit fishy to me that it started acting up as soon as we left the inspection.
I am not electronic savvy to do the work that you did, so not sure what to do if the part is messed up

vedha

john bennette's link gives the diagram and My car had the same
problem I replace capacitor and the resistor gear shifting problem
is solved for my surprise the honda dealers gave me wrong info.
I went to radioshack and spend only 3$, its already 2years now still working.
But the only problem I have now is my speedometer wont work
but stays at 10 m/h always as soon as I start the car hope some one will give some idea. I have changed ecu and tcu. the speed
sensor but still mwont work. any idea friends.

tina harper

thanks for responding. I am looking into some options to replace the tcu. I found an internet place that has rebuilt tcu's for about $140 which is better than the quote I got from a friend of mine who works in a honda dealership parts dept. - $500 for a tcu. I don't know if it is a new one or refurb. Hard to imagine that it is new for a 1991. My friend said another part needed replacing, I think a diffuser? which would cost $36 It has to do with why it wont come out of park when started.

vedha

got to junk yard you may get it for 50 or 60 or pay 140 sure it works fine you dont need a new part for a old car my friend

John Bennett

I doubt the workers at an inspection station would have the inclination, skill, or time to swap out your son's TCU. They may have tried to hook up some type of electronic emmisions data recorder to the car's electronic system and messed something up.

Quickie oil change places have been known to mistankenly drain out a car's transmission fluid and double-fill the engine oil. I know several people this happened to.

tina harper

The safety inspection was done at a garage with auto mechanics and not an oil change place or quick inspection place. Thanks for the info. When I get a day off of work I am going to spend some time on this.

tina harper

tina harper

We took the tcu out by following John Bennett's directions and found the exact capacitor was leaking. Found a replacement, not exact but 25v, replaced and reinstalled. The s light doesn't blink any more it is now staying solidly on, but the gear shift still will not come out of park unless we use the key in the shift lock slot and moving it to neutral before starting. One thing I forgot to mention was that his brake light was on for a secondary light being out which we didn't replace but the light was off when we picked it up after the safety inspection,(guess the guy replaced the bulb) any chance this could cause a problem with the gear shift not engaging?
Thanks John Bennett for great instructions on the TCU. Cost me 50 cents plus the drive to the store.

WebDawg

I think their is a sensor around the brake pedal. It has to sense that the brake pedal is depressed for it to be taken out of park. Also I think that their is a deal in the shift unit itself that unlocks the shifter electronically when the brake pedal is depressed.

TCU's can be found at junkyards but a DIY fix is pure win.

Nice.

xfiles2012

Hello guys i have had that same problem with my wifes car. You just need to remove the tcu from rt floor panal. Look at the copasadors and transisters. Look for leeking or burnt. Go to Radio Shack to replace. Fixed mine for $3.00. Email me for more info. xfilesmg@yahoo.com