Guys,

My TCU finally told the whole story. It went into limp home mode, with "S" light solid and stuck in some high gear.

I removed it and found one or maybe 2 leaking capacitors and a burned resistor almost exactly as described here:

1991 Honda Accord Transmission Control Computer Unit Repair

except that mine was in worse shape and the green ink is flaking off under the caps. Does anybody know if I have to find something to "paint" over that layer? It's not bright, exposed copper, but it's definitely caused by the goo leaking out of the capacitors. I wouldn't want to put new components in just to have it short out all over again.

I've attached a pic but it's a little hard to make out due to the glare. It's right where the pen cap is pointing.

Thoughts?

 

A much better picture...

 

You can probably get away with leaving it exposed. I'd bet the the capacitor or resistor failed, and the the paint was eaten away by the leaking capacitor.

Electronic stores like radioshack may have some paint that would meet typical PCB specs.

 

Thanks PA.
Three caps and a pack of resistors at Radio Shack cost me $6.01. Thank God I have a coworker who has more soldering experience than I do. He hooked me up on the Main Relay too. Man I'm gonna owe some Karma after this!

 

You may find soldering to be difficult. The entire board is sprayed w/ a clear varnish, probably urethane. This makes it very difficult to solder unless you heat and scrape the varnish away. The acid from the capacitor has etched away varnish and board mask, and may also etch away the copper.

I had a failure on ECU of 1997 Acura 2.5TL that was caused by leaking capacitor and it etched right through one very tiny copper foil element. It was so tiny that i could not repair, even w/ a very good magnifiying glass. I could see it OK, but my tools (25w soldering tip) were like using a welding torch to solder. They did more damage than repair.

A used ECU is readily available at cheap price if you run into problems.

good luck

 

Woo Hoo!

After component replacement TCU shows no codes, "S" light stays off unless shifter **** Sports Mode button is pressed. Starts in 1st gear and travels through them all.

For the life of me I can't really tell the difference between Normal and Sports modes however. She seems to shift into 2nd at around 17 mph, 3rd at around 27, 4th up around 40 no matter which mode it's in. Shifting is a little harsh too.

From what I've read around here and elsewhere, it's possibly from not using Honda AT fluid. Worth a drain and refill I guess. I still need to check the solenoids for proper readings. They seemed to operate ok when I put power to them. I'll see what others online have to say about harsh shifting. I can totally live with it but I wonder - Do you guys have any other suggestions for causes and testing?

 

Those hondas were known to shift a bit harsher than newer cars.

There is a cable that goes from the throttle body to the transmission that you can adjust. You want to take up most of the slack.

 

^and check the mounts...but I'd check the throttle control cable first.