Transmission Codes - action to take?
 

Forgive me if this information is elsewhere. I couldn't find it in the DIY section or here with "Search this Forum".

Symptoms:
My 500 dolla special 1990 Accord shifts as if it's in Sport mode but I don't think it is. It eventually goes into 4th. Plus it seems to not want to kick down a gear when I take my foot off the gas and coast. The previous owner mangled the Sport Mode button and wires so "S" light is not a good indicator.

Diagnostics:

No codes via CEL or S light on dash.

Removed and inspected the 2 sets of solenoids on the front of the transmission. Shift sensor and I forget the other ones name - lockdown maybe. What I can see looks fine.

Removed negative battery cable for a minute and removed 7.5a backup/radio fuse in under-hood fuse box.

The car wouldn't start after these 2 things. It eventually did but that may be a red herring and this is about the Transmission codes.

After a cruise around the block during which it seemed to shift a little better I jumpered the service port leads.

"S" light or LED on what must be the Transmission Control Unit on passenger foot area blinks codes 1, 2, 7, 8. These codes directly correlate to the 2 solenoid valve sensor things I had removed and inspected.

My questions are:
Does the fact that the codes are coming up mean that the solenoids need to be replaced?
Do I need to do some voltmeter testing on the plugs that the solenoids plug into?
Or should I pull the TCU to inspect for damaged components?

Thanks guys,
Rob

Thanks, I just might be. How do I test the ones I've got first?

Well I know what step zero is, which is "go buy a multimeter", but unsure how to test them other than reading the blink codes.

The way I have always tested them is by hooking them up to my bat. and if they click if they do they should be good. But I don't remember the volts they are suposta push out when testing them with the meter....

That's even easier. Just run a wire from one lead in the solenoid plug to the pos and one to the neg, or ground to the block? I can do that.

yeah the pos and neg. on the BAT. NOT THE CAR.

This is the best answer for this problem..and if some one out there knows the volts...please put it in soon as you see it..

WheelBrokerAng :)

The solenoids use 12V. There may be a screen on the solenoid to clean.

good luck

TX, yes there is. Along with the screen, check/clean the solenoids themselves....The below might help as well.

Honda Electronic Transmission Problem- Troubleshoot, Inspection, Repair, Replace.

Then, when was the fluid last changed and what type (Honda DW1 or Z1, I hope) was used.

Then these also can/will build up corrosion at the connectors, so while testing them be sure both sides of the connector(s) are clean.

Thanks for the help. That link is why I took the solenoids off to inspect them when I wasn't getting any error codes, but I guess I mentioned that in a different thread. One thing he doesn't tell you is how to take them apart to inspect the solenoids themselves. He just shows a pic of them in pieces.


Anyway I tested them by attaching power from the battery as suggested and the clicked. The lower ones didn't click as loud but they still clicked. Those are the shift solenoids, correct? Should they act identically to the upper ones?

Thanks Guys

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 knob 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.