94 Camry Transmission (AT) Erratic Shifting
 

My 94 Camry downshifts at low speed (15 - 25 mph) and high speed (45 - 60 mph). It accelarates smoothly from a stop and as it accelerates and shifts from 1st to 2nd or from 2nd to 3rd it suddenly down shifts and then returns to the current gear.

Start by changing the trans filter, you probably have some debris in there. Also look for metal particles in pan.

I've changed the fluid and filter. I've checked solenoid's #1 and #2 operation in and out of the trans. Both seem to be working good (makes clicking noise when 12V applied). I've checked the wires from the solenoid's connector to the ECM. No short or open found. I've even checked the trans operation with the solenoid connector's of the shift solenoid 1 and 2 and the shif lock soloenoid disconnected. Transmission shifts smoothly. Reconnect the connectors and the erratic operation returns...

If the trans operates OK with the solenoids disconnected it may be a solenoid or a sensor for the trans.

Check solenoid SL.

The adjustment of the downshift cable running from the throttle to the trans.

Throttle position sensor adjustment.

Hows the speedometer operation, OK?

I haven't checked the SL solenoid for proper operation in or out of the transmission. The speedometer has been another problem that I've had for a little longer than the erratic shifting. The speedometer advances when I turn the key to start the engine and it bounces and does not stabilize at the correct speed while driving. I ve already replaced the speed sensor and the speedometer shaft and gear. It still is operating erractically. I've also checked the wires from the speedsensor to the speedometer in the dash. I have been working with the adjustment on the throttle cable and the throttle downshift cable. I haven't looked at the throttle position sensor yet.

Might be the speedometer system. The trans also uses this for operation. Erratic speedometer operation could mean erratic trans operation. May be the reason the trans operates OK when the wiring is disconnected.

to toyomoho - I replaced the speedometer speed sensor awhile back and still had the erratic speedometer. when this erratic shifting problem started, I checked the speed sensor and found the bolt that secures it broken. I bought a new speed sensor and compared the operation and both were the same. Haynes says it should change from 0V - 12V+ 20 times in one revolution of the shaft. Both sensor's changed only 4 times during one revolution of the shaft. I put the old sensor back secured only with the o-ring internal (not able to remove the broken bolt piece). During my adjustments of the throttle cable and the throttle downshift cable the erratic speedometer seemed to change from lots of bouncing to vey little bouncing in the guage. Also, I checked the wiring from the speedometer sensor to the speedometer gauge. No shorts or opens found.

4 cylinder or V6, makes a difference in the trans.

to Joey P - 4 cyl., LE, 4 dr., sedan, 4 spd. w/overdrive. Checked the SL solenoid. Makes clicking noise in and out of trans. Continuing adjustment of the throttle cable and throttle downshift cable. Also adjusted the cable that connects directly to the throttle. Turned it counter-clockwise (backed it off) and I think it changed the shift point (made it higher in RPM range in shifting, 2nd to third, etc.). Still downshifts erratically, mostly at lower speeds, 15 - 30 MPH.

I sent you a private message with a link some info.

94 Camry A140E Transaxle
 

I would be interested in those diagrams if you still have them.

Also - I am getting error code 42 for the speed sensor. The Speedometer is erratic, and so is the shifting. It actually got worse when I put a new Speed Sensor in the car.

I would also like to know if anyone knows what this is referring to:

Disconnect the cruise control ECU and PPS connectors

It is on troubleshooting page 82 for the speed sensor, I attached the pdf for your reference.

Thanks for your help.

More Info
 

Just to add a bit more info:
I took out the Speed Sensor and kept it hooked up to its electronic connector and spun it with a drill. My wife recorded a video of the speedometer as it reacted. It was smooth even at different speeds of the drill.

So how does that jive with the speedometer being erratic when doing a test drive of the car? It is smooth with a drill spinning the Speed Sensor, but erratic when the car is actually driving down the road, (at low speeds around my neighborhood).

Thanks for replying sparkybuoy,

The new Speed Sensor only cost about $13, compared to about $150 so maybe that might be the problem. I will put the old one in to see if it is better.

You mentioned in your earlier post that erratic shifting could be caused by Valve Body to Case O-Ring and/or the 2nd Coast Brake tube seal OR valve body check balls.

Do you think these might be part of the problem, or do you think that because the speedo is erratic that it is not these but the Speed Sensor instead.

Also any idea about this statement that I mentioned above:

Disconnect the cruise control ECU and PPS connectors

It is part of the Troubleshooting procedure for the error code 42 that relates to the Speed Sensor.

Thanks for any help you or anyone else can give.

So I put the old Speed-Sensor back in and it is at least derivable now. However there is still a little erratic movement with the speedometer and corresponding erratic shifting when it gets near the speed that it needs to shift.

Do you guys think that this is the Speed-Sensor, should I buy a new (High Quality One), or could it be something else?