Auto trans dies after short drive?

[irelandmc]

I have a 92 LX auto. I bought it with the same symptoms it's having now, which is that after driving for about half a mile the transmission stops transmitting and 100% slips in all positions.

- Car had this problem when purchased, TCU code 15
- No visible TCU damage, swap TCU with no change in symptom
- No obvious causes/component failures, so I swapped the transmission, including torque converter
- Car ran fine for about 800 miles, but gas mileage was low 20's (stock A1 motor w/new plugs, filters & fresh oil)
- Then it died again. Now I'm back to the starting point.

My next step is painstaking harness testing, but I wanted to see if anyone else has experienced these sympoms and what if any was the resolution?

I wonder why I got 800 miles out of the swap?

Thanks for reading!

[Tishock]

You didn't mention the NM speed sensor, did you check it?

Carefully inspect the A/T speed sensor before installing. Do not install if it shows signs of being dropped or improperly handled

Originally Posted by TECHAUTO
CODE # 15: NM Speed Sensor

NC/NM speed sensor, code 9/15

Symptoms of a faulty NM speed sensor: Located at the end (passenger side) of the transmission on some models, check for code 15 or transmission jerks hard when shifting. Symptoms of a faulty NC speed sensor is the lock-up clutch does not engage. The NM or NC speed sensor (code 9) should be within 400-600 Ohms at 20-degrees C. If they are not within spec replace them. If they are within spec check for a possible short to ground but first unplug the harnesses at the TCU.

How to replace the NC speed sensor:

1.To locate the NC speed sensor on the back of the transmission follow two wires connected to the sensor. The sensor is located on the transmission between the engine firewall and the transmission towards the tire's mud guard on the 90-93 Accord. The NC speed sensor appears to look like a fuel injector (not the best of description.)
2Reach inside with a 10 mm socket wrench and unbolt 1 bolt that holds the speed sensor in place.
3.Carefully twist the speed sensor as you pull it out.
4.Replace the O-ring.

How to replace the NM speed sensor:

1.To locate the NM speed sensor on the front of the transmission follow two wires connected to the sensor. The sensor is located on the transmission between the engine radiator and the transmission towards the tire's mud guard on the 90-93 Accord. The NC speed sensor appears to look like a fuel injector (not the best of description.)
2.Reach inside with a 10 mm socket wrench and unbolt 1 bolt that holds the speed sensor in place.
3.Carefully twist the speed sensor as you pull it out.
4.Replace the O-ring.

http://media.honda.co.uk/car/owner/m...l/400/9-62.pdf

[irelandmc]

I got 511Ω and 505Ω on the sensors that I pulled out with the original trans. I’m going to check the new ones and the harness next time there is time to play with it.

[irelandmc]

Got out to the car's temporary home.

- Verified that code 15 had returned
- Got 496Ω and 501Ω on the nm/nc speed sensors on the replacement (currently installed) trans
- Grounds for both sensors were good

Still need to try cleaning the connections, but the rest checked out.

[lbus9168]

I had that code. i just pulled out the sensor and cleaned it, and then it worked. haha. resistance measured correctly but it couldnt read due to a very small build up of particles. it was only a few specs but it was enough to make it fail to operate. my smyptoms were no where near as bad as yours: at highway speeds the trans would Make the motor float around by about 3-400 rpm.

Also, with regards to your mileage issue, just disconnect your O2 sensor and see if that helps. common failure point. youll get a CEL but mileage may improve.

ive had both of these issues.

if you replace the O2 use a Denso. nothing else, my ntk failed.

[irelandmc]

Thanks for the tips. I'm thinking the mpg problem may be the trans never locking up. I'll try cleaning the sensors.

[irelandmc]

Fml

This morning out of boredom I removed, cleaned (filed to bare metal), and reconnected all of the harness grounds. So far the car test drives perfectly. Filled the tank, so I'll see how the mpgs do here in a little while, but I'm tentatively calling this solved.

Makes sense in hindsight that I might get a few hundred miles out of the cursory wire brush cleaning the grounds got during the swap.

I should have known. Clean your grounds people!