I did a search and didn't find the answer I was looking for.

I have a '90 EX, automatic.

Here the situation, with the switch on NORMAL the trans will automatically switch to SPORT mode. To get it to switch back, I have to pull over and turn the car off then back on again. Pressing the button does nothing. It satys is Sport mode. Sometimes, it'll switch back from Sport to Normal by itself.

What would cause the trans to automatically switch from Normal to Sport even though I have not pressed the button? Is there a solenoid that can be disconnected similar to say an american style transmission like a C4 with a transbrake?

Thanks,

 

I got this off another site but this should tell you what to do:

When the A/T control unit senses an abnormality in the input or output Systems, the S indicator light in the gauge assembly will blink at equal intervals and the LED display on the A/T control unit will blink a problem code when the ignition key is turned on.

However, when the Service Check Connector (located to the lower right of the glove compartment) is shorted with a jumper wire, the S indicator light will also blink the problem code when the ignition switch is turned on.

When the S indicator light has been reported on, short the two terminals of the Service Check Connector together or pull the passenger's side carpet down from under the dashboard. Then turn on the ignition switch and observe either the S indicator light or the A/T control unit LED display.

Problem codes 1 through 9 are indicated by individual short blinks, Problem codes 10 through 1 5 are indicated by a series of long and short blinks. One long blink equals 10 short blinks. Add the long and short blinks together to determine the problem code.

Once we know what the DTC is, we can work from there.

 

Thanks sir_nasty. I found the same.

What's different with mine is that the "S" does not blink. It simply goes into Sprot mode and the light goes green. It as though the button was depressed even though I never activated it.

 

does it blink when the ignition key is first turned on? is the CEL light on at all?

 

No, the green "S" does not blink and CEL is not on. The symptom is intermittant. I'll be driving and it'll just switch to Sport, then back to Normal. I plan to change the trans oil with Honda ATF Z71 this weekend. Man, dealer gets $6.60/qt! What's in it that so different then any brand name Dexron III? Even the power steering requires honda specific fluid, which I have used.
Thanks,

 

Is the Honda brand trans fluid the only recommended replacement fluid? Will any others work acceptably?

What does the "sport" setting/button actually do? I haven't driven mine enough to know yet...

 

Shop manual calls for Dexron III. However, every honda owner I spoke with recommends using Honda ATF Z71 trans fluid. There must be additives in it to keep bands and clutches from premature wear. I wish there was a Honda ASE tech online to answer this one. What makes honda's internal clutches and bands different? Maybe they're weaker then american made tranny's and require these additives to keep them together. I admit imports are reliable, as long as you don't modify them. They can't handle abuse.

 

Damn right, They can can take the obuse even if you modifiy them

 

DesertHonda is a Honda certified Master Tech. and says don't use anything but the ATF Z71 fluid... why? no idea... but they can take some fairly serious abuse... There is more than one person on here with a Turbo motor on stock internals and transmission....

 

Honda-brand ATF may not have existed in 1990.

Try jumpering the SCS connector as if you were reading error codes with the flashing check-engine light. Maybe then your "S" light will blink.