Hi Everyone,

I have a 91 Honda Accord LX. The “S” Light was intermittently coming on and downshifting the transmission. Now the “S” Light won’t go off and the transmission won’t go out of 3rd gear. Here is what I have done so far:

- Jumped the service check connector, no error code given
- Removed the 7.5A Backup fuse for 1 minute and replaced
- Disconnected and reconnected the positive battery terminal
- Unplugged and inspected the Transmission Control Unit – no visible damage apparent

Any other ideas? I have minimal mechanical/electrical knowledge – please be specific. Thanks for your help!

 

UPDATE

I bought a TCM on ebay for $142 and swapped it out with the old one. Problem solved!

 

What is a TCM? I have the same problem on my 91 accord!

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by aharrison06 &raquo;</TD></TR><TR><TD CLASS="quote">What is a TCM? I have the same problem on my 91 accord!</TD></TR></TABLE>Transmission Control Module

 

It is located in the floor under the glove box. Pull up the carpet and it is on the right side of the metal housing. The Engine Control Module (ECM) is on the left side of the housing.

 

if the s light is green....thats the sport button light baby

 

Thank yall very much!!!!

 

Hi, I also have a 91 Honda Accord and my light won't go off. I know nothing about cars just found this because I don't feel like being ripped off again, so I googled car diagnosis. Anyway my question is, I noted you said you bought a TCM what is the name of this part so I can try to price it and is it something I could put in or is it a difficult part

 

Go to ebay and search for a Transmission Control Unit for your model car. It is critical that you you get the serial number off the old TCM so you get the right part. Match up the serial number with the serial # on the new unit on ebay before you buy it. Swapping out the old unit is not that difficult. My earlier post has the location. You will need a metric socket (can't remember the exact size - possibly 10 mm?) and an extension for your ratchet. Once you have the housing off, unplug the 2 wire bundles going into the unit and install the new one. Here is the description on my unit - IT MAY BE DIFFERENT ON YOURS.

AT Control Unit
28100-PXO-823-M1 3LX
Lot No. 1603U
OKI Telecom

Good luck.

 

One more thing, the housing has 2 modules, the ECM and TCM. The TCM is on the right side.

 

Hi, I have a 91 Honda Accord as well and the "S" light is on and off at random. The shift lock stops working at the same time the "S" light is on. Are these both controlled by the TCM or do I have two problems? The TCM was replaced by the privies owner from a salvage yard.

 

sounds like the TCM. you can have your rebuilt for 100 bucks if you cant find a replacement.