Without warning the automatic transmission on 93 Accord started acting up. Vehicle does not accelerate properly, engine revs up but trans acts like its slipping. D4 light is now on steady. Shorted the service connector and got 4 long blinks and 1 short blink on MIL light. Service Manual doesn’t have such a code. How do I interpret???

Car has been very well maintained, trans fluid looks good and red. I hear some fluid noise when shifting between gears???

Car has almost 200K, so if I need a rebuilt transmission that’s fine, but I don’t want to assume it’s toast just yet. Just want to make the proper diagnosis.

 

Is Check Engine Light on also? Code 41 is valid code for O2 sensor heater circuit fault (short or open detected).

Trans codes are flashed on the D4 light, not Check Engine Light.

Suggest resetting ECU by pulling 7.5A BackUp fuse in underhood fuse box for 20 secs. Recheck TCU codes checking for D4 light flashes.

good luck

 

No, check engine light is not on, only D4.

Code 41 is O2 sensor and heater…interesting, dealer just replaced oil pan last week. Wonder if o2 sensor wiring got messed up. Could this affect transmission operation???

I’ll try reseting ECU and see what happens.

 

If you read code on MIL light (Check Engine Light?), then code is Obd1 code. Trans codes are only presented as flashes on the D4 light, same flash code as Check Engine Light.

good luck

 

Good news!!! Pulling the back-up fuse to reset the ECU cleared the D4 light and MIL code. Test drove the car ... transmission is now functioning normal and no codes came back. Thank you for your input I was ready to condemn the transmission.

Does this mean the O2 sensor and wiring needs to be checked???

 

Checked wires/routing and the connectors for the O2 sensor last evening and found no issues. Drove the car about 10 miles without any issues. This morning however it started acting up again. I haven’t verified the code, but I’m guessing it’s the same code 41, problem in the heated oxygen sensor circuit.

So I’ll need to go through the troubleshooting procedure for the O2 sensor. If the sensor shows to have a problem, is this hard to change out? On the EX model it’s located on the exhaust pipe underneath the engine. Do I need the special tool to remove/reinstall?

 

In my experience cod 41 does not cause any detectable symptoms. However, it may be possible.

It is not hard to diagnose or replace.

Diagnose - Disconnect electrical connector and check heater element lines (2) for resistance. If open or short, then O2 sensor must be replaced. You will need a wiring diagram and shop manual to know which wires to test on the released connector.

Replace - You will need a large open end wrench (22mm or 7/8") or special O2 socket (cut out to fit around wire harness). O2 sensor can be tight. It may help to warm the car for 5 mins before attempting to remove.

good luck

 

Things have not gone well on the transmission diagnosis today. I've got a bad feeling about this.

My son drove the car to school today. He said transmission again acting like it was slipping. He got home this afternoon and I had him check for codes with the service connector. Didn’t get any MIL codes but the D4 light was on solid.

Any suggestions what I can check next?

 

Did the MIL turn on while driving, or did the D4 light start flashing?

When you checked for codes, did the MIL turn on and stay on?

 

There were TCU problems on these early 90's Accords. Your symptom of D4 light on full time (I assume even w/ trans selector in something other than 4th gear?) suggests possible faulty TCU. Other symptoms are clicking main fuel relay (under dash).

good luck