both the vss and oss (0500 and 0720 code reasons) can make the trans shift erratically, so, assuming the trans and diff fluids have been changed at 30k intervals since it was new, i'd say to replace both sensors and see if that fixes the problem before worrying about the trans.
tony

 

Ok, thanks. I ordered an output shaft speed sensor. The speedometer has always worked normally; could the vehicle speed sensor still be bad?

 

watch the odometer next time it acts up. if it goes blank and the shifting is erratic then look up my threads on this issue. I had same codes pop up and stumbled upon a thread about the resonator in the speedo going bad. I changed it out and never had an issue. drove the car another 20k or so before selling it. good luck

 

What do you mean by "goes blank?" I have a mechanical odometer.

 

Last time I changed out a Output Shaft Speed Sensor I at least ohmed it out before buying a new one. IIRC it was an open circuit. Was a real easy fix too, and it did fix the shifting issue. Was on a 2000 Dodge Dakota. That was 2-4 years ago, I think. Transmission still shifts fine today.

 

Update: changed the trans output shaft speed sensor. No change in behavior.

To add some more info: the car is, right now, shifting fine in gears 1-3. It does not like to/want to shift to 4th gear. When it does try to shift into 4th, it feels as though the transmission "drags". The vehicle slows a bit, like a manual transmission car on deceleration, and it shifts back to 3rd.

Check engine light remains on.

 

Changed vehicle speed sensor. The little magnetic ring was cracked. First drive, when the transmission was cold, was great. Shifting smoothly, if slowly, shifted into 4th like normal...

Yeah. So much for that. I noticed the car was not shifting down into first when I came to a complete stop. It would leave a stoplight in second gear. I pressed the "PWR"/ECT button, and it then revved all the way out to the redline before shifting in first. It did not appear that the transmission was slipping, though, as the road speed seemed to match how fast the car should be in its gears (about 35-40mph by the time it shifted). Not 100% positive on that, though. I was a little preoccupied in not bouncing off the rev limiter.

When I turned PWR off, it resumed its old behavior; it wouldn't shift into 4th. I was also greeted by a flashing O/D Off light. That did not go away after a restart, but it did go away when I toggled PWR again.

The check engine light has remained on during this process; should I have the codes cleared before attempting any further fixes? Any suggestions overall?

Thanks,
Nate

 

Has there been a resolution? I am having the EXACT same issues and have completed the same "possible" solutions as well as soloniod replacement with no luck.

 

I haven't found a solution, no. I haven't changed anything, but this issue seems to only occur after the car sits for a while and the battery drains. After driving the car around and shifting manually through about a tank of gas, it has behaved as expected. The car now has 267k miles and seems fine. Shifts up and down through all four gears, doesn't slip, shifts firmly but not roughly.

 

While dealing with a minor accident & repair on my 2001 M5, I've been tootling around town in the old Camry. I've noticed the transmission's odd behavior has gotten worse, so I decided to yank out the ECU and see if I could find anything. Maybe a loose pin or something, who knows.

From my research, it seems that the vehicle speed sensor sends a signal to the cluster, which in turn sends a signal to the ECU. The speedometer had never been an issue, and the odometer had always worked, so I guessed that something in the ECU might've gone awry.

Removing the ECU is pretty simple. There's a snap-in panel that goes above the passenger's feet; find an edge and pull down. Above that, two Phillips screws hold the lower dash trim piece in and then it pops off. That exposes the 3 "bullet nose" 10mm nuts at the lower edge of the glovebox door, which simply unhooks and pulls out. There are 5 Phillips screws holding the glovebox itself in place; 3 on the top edge and two at the bottom. Pull the glovebox out, then unclip and remove the wiring connectors from there. Just behind the glovebox is the ECU (big gray metal box w/ two Phillips screws in it). Disconnect the wiring connectors; there are 4 from top to bottom. Then, remove the slightly hidden 10mm nut at the top and to the right on the same bracket as the 2 Phillips. Then undo the two visible screws.

At the bottom of the ECU, undo a 10mm nuts, holding a bracket holding the cruise control module. Move it out of the way. Then, just behind the cruise control module, remove 2 more 10mm nuts, and pull the ECU forward. It will come out with a bracket attached to the back.

From there, it's easy to open up the ECU itself; it's just another set of 4 Phillips screws. One side of the ECU was sealed by a Phillips screw covered in solder, but the other side pulled off with 5 Phillips screws.

Here's what I found inside the ECU:

It appears whatever capacitor this is has puked all over the circuit board. I'm guessing that's not great for the long term reliability of whatever this controls. Does anyone know what this does?

 

I went to my local LQK Pick Your Part junkyard and grabbed two ECUs.
One matches the OE Toyota part number exactly (89661-33420) (VIN JT2GK13E6S0086786).
The other doesn't (89661-06200), but comes from a 1995 V6 LE Automatic Camry (VIN 4T1GK12EXSU088425). The circuit board has a more brown color to it.

Are the part number differences important? The two ECUs appear nearly identical:

You can see in those photos that the green-er (Japanese?) ECU has already puked from both of its capacitors, which makes me want to use the brown-er (American?) ECU.

What do you folks think? Should I just repair the ECU I have? Or can I use the non-numbers matching ECU? I would appreciate any insight you have.

 

They make “RECAP” kits to replace these aging capacitors, so if you’ve got desoldering/soldering skills you can replace them yourself. The leaking dialectric from that capacitor is a failure mode and the circuit will not perform as designed. The dialectric will also eat through the conformal coating and burn through the thin electrical traces printed on the printed circuit board (PCB). This is also a hard failure mode and makes the pcb economically unrepairable. The color difference is nothing to be concerned with, different suppliers and manufacturers use different colored circuit boards as well as different colored conformal coatings. As far as the part numbers of the ECM is concerned you MUST use the original part number or the official Toyota “superseded by” part number for your EXACT VIN#. You can get these part numbers and availability from your local Toyota Parts department. When our Toyotas get to this age, I periodically go to the pick-n-pull and grab several as they’re usually around $25 each. I open the ECM and physically inspect for leaking capacitors before I leave the yard with them. Another option is to go with a company that specializes in remanufacturing and testing these ECM’s at a much higher price, usually $200-$300 or more, but most have a fairly short warranty period, typically a year or so.

 

They make “RECAP” kits to replace these aging capacitors, so if you’ve got desoldering/soldering skills you can replace them yourself. The dialectric will also eat through the conformal coating and burn through the thin electrical traces printed on the printed circuit board (PCB).

As far as the part numbers of the ECM is concerned you must use the original part number or the official Toyota “superseded by” part number. You can get these part numbers and availability from your local Toyota Parts department.

Is there an easy way to find the “superseded” part numbers? In BMW land, where I’m much more familiar with websites and diagrams, I can pull that up in <10 seconds.

 

I have some mild soldering skills. This board looks pretty easy to me.

 

You’ll want to use very good lighting and high magnification to ensure the traces have not been etched away by the dialectric. You must first clean the leaked dialectric with a small acid brush and 100% IPA to ensure that an adequate inspection can be performed. A solder sucker, copper wicking braid and a small chiseled soldering iron tip will be needed.

 

btw, the 1990’s saw rapid improvements being made by Toyota in their ignition and engine control management circuits with rapid changes sometimes within the same model year, and all of it is controlled by the ECM. That’s why you can’t just use “one that’s close” to yours.

 

Did some of my own research. According to this page, the ECMs I have are both "supercessions."

1995 Toyota Camry Sedan LE (VIN starts with J) 3.0L A/T Engine Control Module. Electrical - 896613342084 - Genuine Toyota Part

Engine Control Module. Electrical. 1995 Toyota Camry Sedan LE (VIN starts with J) 3.0L A/T. Genuine Toyota Part - 896613342084 (89661-33420-84, 8966106200, 8966133420)

parts.toyota.com

I'm not familiar with the Toyota Parts website. Am I reading it correctly in that 89661-06200 is newer than 89661-33420?

 

If your ECM part number that came out of your Camry ends in xxxx84 or xxxx-84 than your computer had been replaced already at least once. That’s why I stated you need to call the dealer and talk in person. If it was replaced by someone other than you, you can’t bee 100% sure that the previous person used the correct part or correct superseded by part.

 

Ok, so -84 would be a reman'd part?

Based on the numbers below the part number, I would guesstimate that 89661-06200 is a newer part.

 

Here are the ECMs I have on-hand. Neither has been installed. The ECM with the matching part number also has corroded/failed capacitors.

 

Do you happen to have a J-VIN Camry? One that was manufactured in Japan?

 

You “may” find, and I mean the possibility may exsist, that they are interchangeable with US Camry ECM’s in the superseded versions but no guarantee. One of my Camrys is a J-VIN and the ECM went out (leaky cap) on the ignition ckt lines and I ran into this problem just last fall. While you may get the engine to actually run with a simple swap, differences in ignition, engine control and transmissions could make the car undriveable.

 

For sure. I don't want to damage anything else, of course, which is why I asked here

 

Good luck! And please post a follow-up after the repair as many folks are having the same issues now that these 90’s Toyotas are starting to fail electrically, esp the ECM’s.

 

Thanks, will do. This problem has been vexxing. It's particularly frustrating as no mechanic ever wants to actually diagnose problems - they always just want to change out the transmission -_-

Which is why I do mostly my own work. I go to Costco for tires, and a local shop for alignments, and that's about it. Up to and including my M5's engine rebuild.

 

Note that this thread is 3 years old, haha.

 

For anyone curious, these are 10uF 50V capacitors. Commonly available -

EEU-FC1H100LB Panasonic Electronic Components | Capacitors | DigiKey

Order today, ships today. EEU-FC1H100LB – 10 µF 50 V Aluminum Electrolytic Capacitors Radial, Can - 1000 Hrs @ 105°C from Panasonic Electronic Components. Pricing and Availability on millions of electronic components from Digi-Key Electronics.

www.digikey.com

10uF 50V Electrolytic Capacitors - Pack of 10

We like capacitors so much we made a kids' show about them. They're super handy and it's really helpful to have a variety lying around to pick and choose ...

www.adafruit.com

 

Bought a recap kit + 4 more 10uF 50V capacitors.

 

get a good "solder sucker" and temp controlled iron. Use high quality rosin core electrical solder, Kester is a good brand and non-RoHS LEAD solder is best.

Pay close attention to POLARITY (+/-) as electrolytic (EL) caps only go in one way. Don't overheat traces or they can come off board and you'll need to replace them with wire.

ALL EL caps this old need replacing, good luck!

 

get a good "solder sucker" and temp controlled iron. Use high quality rosin core electrical solder, Kester is a good brand and non-RoHS LEAD solder is best.

Pay close attention to POLARITY (+/-) as electrolytic (EL) caps only go in one way. Don't overheat traces or they can come off board and you'll need to replace them with wire.

ALL EL caps this old need replacing, good luck!

Yeah, I can’t wait until all the slightly more modern circuits in my BMW start to blow, ugh.
I don’t think leaded solders are common in California, but admittedly, I bought some rosin core solder years ago and haven’t looked too closely since then.

 

Hmm. Not sure this is salvageable.

 

Alright, so I tested this ECM before putting it in my car/messing with the capacitors, and got a P1600 code - ECM Batt malfunction. Car ran fine, though, and shifted into all gears fine.

I figured, well, good enough time to practice my soldering and get my process down before attempting to repair the OE ECM. Here's the result:

Yes, it's ugly. And yes, I probably put too much heat into the PCB. It's probably not as durable as OE.

But it works! Transmission seems to be shifting fine (and it wasn't this morning), and though I still have a P1600 code, since that was there before I started, I'm calling that a win.

Now that I have a much better feel for what the heck I'm doing, I'll perform this repair on the OE ECM from the car. Its corrosion damage is much lighter.

 

I have spare capacitors plus a rebuild kit from BlendDoor.com, so I'll tackle the failed capacitors first, then go for the other ones on-board that haven't failed yet.

 

Update - transmission feels like it's shifting smoother than I've felt since I started driving it in 2014. Quite impressive. Still have a P1600 code, so I am going to repair the factory ECM and put it back in.