I started having problems with my accord's auto tranny not shifting in D4/the light staying on D4 and having to shift manually through the gears so as not to damage the clutch. After looking/asking questions for a while, I found out that it was probably the Transmission Control Module/Unit (TCM/TCU). I've found that the part is over $500 new and am going to replace through used parts but am not sure where the module is at. Is it the unit just below the shifter or where is it at?

I started having problems with my accord's auto tranny not shifting in D4/the light staying on D4 and having to shift manually through the gears so as not to damage the clutch. After looking/asking questions for a while, I found out that it was probably the Transmission Control Module/Unit (TCM/TCU). I've found that the part is over $500 new and am going to replace through used parts but am not sure where the module is at. Is it the unit just below the shifter or where is it at?
Also, for all of those people who have found they have the same problem, I was told that you could do the following to test if the module has failed:

1. Turn the ignition switch on but do not start the engine. If you can shift it out of gear with no further steps, you've found the problem.
2. Start the car and depress the brake, you should hear a click as you do; if not, you've also found the problem.

Also, for all of those people who have found they have the same problem, I was told that you could do the following to test if the module has failed:

1. Turn the ignition switch on but do not start the engine. If you can shift it out of gear with no further steps, you've found the problem.
2. Start the car and depress the brake, you should hear a click as you do; if not, you've also found the problem.

If we do this and "found the problem", what exactly would that problem be?

I'm having the same (or very similar) problem; D4 light on constantly (while others will come with their respective gear well), stuck in gear (2nd I believe). I can pull the main fuse, then everything will work properly, until I turn the car off and back on, the problem comes back. I tried pulling codes, but the light won't flash, it just remains on. I pulled the TCM, opened it up, but no leaking caps or anything; everything looks good.

My TCM did not have any corrosion or leaking caps that I could find either, but it is a very common problem. After I replaced the TCM with a rebuilt one everything worked perfectly. If you really do not think this is the problem try the main relay but I don't think it is the problem because mine only had 2nd and 4th or 1st and 3rd gear as well.

The TCM's run over $500 new or 176 rebuilt factory direct w/warranty (you have to send yours back w/return packaging labels provided). Good luck trying u-pull-its because they were all wiped out at mine. Here's the number of a place in miami Florida who rebuilds them: 1-800-886-9926. To get the part you may have to tell them you own a garage but make up a name and put your home address, trust me, they will not know.

OK not sure if you have found where the computer is but it is under the passengers feet at the front of the floor board behind the carpet. The one on the far right is the transmission computer the other one I believe is the ECU.

Now I am going to ask you about your problem with the car. Did you only have 1st? Mine I can manually shift it into 2nd and it goes no further.

My 1997 honda accord SE whins and drives very slow when in D4. Also,the engine light comes on. My mileage is 132,000, with only one owner could this be a problem with the TCU and will I need to look for a rebuilt transmission?
Any help would be appreciated

adwalton, check for codes:

https://www.askmehelpdesk.com/cars-trucks/faq-how-troubleshoot-repair-maintain-hondas-selected-other-vehicles-46563-6.html#post832012

Change the transmission fluid:

https://www.askmehelpdesk.com/cars-trucks/faq-how-troubleshoot-repair-maintain-hondas-selected-other-vehicles-46563-14.html#post2634481

If the problem persists, assess whether the problem is with the TCM or other.

I have had all the same problems replaced tranny both cv axles all new fluid the only thing I have left to do is change the tcm my light comes on then goes away then it will flicker and a little sluggish I can put it in park and it goes away but I think it's the tcm I own a 92 accord 154000 miles just bought it the previous owner said he had the tranny replaced but it was bad or the person he had do it did not know what he was doing because I pretty much rebuilt the intire drive train so good luck to all of you

Where is the main relay at

I have 1992 honda accord with a new remanufactured computer it still has a problem . It doesn't shift like it should like the transmission is slipping and has no power going to wheels the rpms go up ? Please help me with this problem thank you .

Duke2275, the clutch packs are likely shot and the transmission needs rebuilding.