I have a 92 Accord LX Sedan Automatic and also having a D4 light issue.

A few weeks ago while driving in D4 it wouldn't shift out of the lower gear. The car would really bog down on acceleration and D4 light would stay on regardless of what gear I selected. If I stopped the car and shift into D1 it would work in that gear but the D4 light would remain on and the same thing in all the other gears. I pulled the TCU cover and noticed some leaking capacitors. I purchased a rebuild TCU (same numbers for a 92 LX Sedan) installed it and everything worked fine. FOR TWO DAYS!

It's now back to doing the same thing as before. Bogs on acceleration D4 wont shift into higher gear and D4 light stays on. I tried to pull some codes but can't get anything. I've read in another site something about a loose ground wire on the firewall but could not understand if they were talking about a 92 Accord. Does this ring a bell with anyone? While it could be another bad TCU it was purchased from reputable dealer who has good luck with their units, is sealed with a one year warranty.

I would really appreciate some help.

 

Pull the back-up fuse in the under-hood fuse box for several seconds to reset the TCM, and see if it goes back to normal at least for a while.

https://web.archive.org/web/20170909...ut4fuseecu.jpg

 

Thanks....and I've tried this a couple of times. It's seems to work only for a few miles and then goes back to the same problem.