Strange Transmission Occurrence/Problem (1 Viewer)

[snowsurflax]

Wife has little feet, so not likely the problem. I did search the NHTSA site and found a bunch more instances of this. Kind of scary to read others having exact or very similar problem to what i described. From what I can deduce, likely a malfunction of the TPS (Gee, Toyota doesn't have MUCH history on faulty throttle problems...). But 5 recorded instances (maybe triple unrecorded?) out of 2 milltion 80 LC's built is pretty damn low occurence. Actually found more problems on the '06 M35 I sold to buy this rig and the '10 Mazda5 we drive around most of the time. It sjust that this problem with the LC is extremely rare but very dangerous.

 

[CJF]

Mentioning accelerator cable, the accelator pedal is pretty damn stiff. You really have to mash it to get going.

I'll bet that's the only thing mechanically wrong with your rig.

 

[Tools R Us]

OK, lets apply a bit of logic.

First try this experiment: Hold the brakes, select any gear, try all of them, mat the throttle and hold it, the rig will not move, the motor will rev to ~2000 rpm and the torque converter will stall. Select low range, now the motor has almost 3 times the gear advantage, the rig will still not move. If you keep doing this, the only thing that will happen is the trans fluid will overheat.

If you still don't believe: Drive the rig at say 50 mph, mat the throttle and hold it, fully apply the brakes, the rig will stop and the motor will be revving ~2000rpm. If you were to somehow lock the torque converter clutch, the motor would stall.

The Cruiser brakes are much stronger than the motor. Even halfway maintained brakes will overcome the motor, even at full throttle.

... From what I can deduce, likely a malfunction of the TPS (Gee, Toyota doesn't have MUCH history on faulty throttle problems...). But 5 recorded instances (maybe triple unrecorded?) out of 2 milltion 80 LC's built is pretty damn low occurence. ...

The TPS is a sensor, senses throttle position and reports it to the ECU, it has no mechanism to open or change throttle position.

Later model vehicles are drive by wire, there is no connection between the controls and the motor, brakes, etc, the '80 series is mechanical, the controls are directly connected to the devices. The drive by wire vehicles have had issues, but even then the brakes should always be stronger than the motor.

For what you are explaining to happen, it would need; brake failure, throttle stuck open and trans shift failure, all at the same time? I can see the trans shift failure, the shift solenoids have been known to stick, fail on the '93-94 trans. The throttle could stick, but then repair it's self? The brakes could fail, but then repair them self? The chance of this all happening at once, then fixing it's self, is about the same as me jumping and landing on the moon?

There are lots of "recorded instances" most not investigated, the ones that are, mostly come out as operator error or undetermined. Most likely; the shift failure happened, this can be intermittent, the operator fixated on the shifter, panicked and held whatever peddle down solidly, logic, evidence says it was the throttle. If the brakes were applied, the rig would not of moved, at least not significantly, as reported.

Do a bit of research on the design, operation of the rig, it is an old school mechanical beast. The chance of cascading mechanical failures adding up to what is reported, then self repairing, is close to zero. Believing the story is forgiving, loving, but isn't likely how it happened.

 

[Frankencruiser]

^ Well said tools.

To the op: while events like these are recorded for virtually every vehicle made, they are almost all operator error. Even the batch of "unintended accelleration" events toyota had last year were determined to be operator error. The only thing even remotely possible (as far as I can tell) is a stuck throttle cable.

 

[bsmart82]

OK, lets apply a bit of logic.

First try this experiment: Hold the brakes, select any gear, try all of them, mat the throttle and hold it, the rig will not move, the motor will rev to ~2000 rpm and the torque converter will stall. Select low range, now the motor has almost 3 times the gear advantage, the rig will still not move. If you keep doing this, the only thing that will happen is the trans fluid will overheat.

If you still don't believe: Drive the rig at say 50 mph, mat the throttle and hold it, fully apply the brakes, the rig will stop and the motor will be revving ~2000rpm. If you were to somehow lock the torque converter clutch, the motor would stall.

The Cruiser brakes are much stronger than the motor. Even halfway maintained brakes will overcome the motor, even at full throttle.



The TPS is a sensor, senses throttle position and reports it to the ECU, it has no mechanism to open or change throttle position.

Later model vehicles are drive by wire, there is no connection between the controls and the motor, brakes, etc, the '80 series is mechanical, the controls are directly connected to the devices. The drive by wire vehicles have had issues, but even then the brakes should always be stronger than the motor.

For what you are explaining to happen, it would need; brake failure, throttle stuck open and trans shift failure, all at the same time? I can see the trans shift failure, the shift solenoids have been known to stick, fail on the '93-94 trans. The throttle could stick, but then repair it's self? The brakes could fail, but then repair them self? The chance of this all happening at once, then fixing it's self, is about the same as me jumping and landing on the moon?

There are lots of "recorded instances" most not investigated, the ones that are, mostly come out as operator error or undetermined. Most likely; the shift failure happened, this can be intermittent, the operator fixated on the shifter, panicked and held whatever peddle down solidly, logic, evidence says it was the throttle. If the brakes were applied, the rig would not of moved, at least not significantly, as reported.

Do a bit of research on the design, operation of the rig, it is an old school mechanical beast. The chance of cascading mechanical failures adding up to what is reported, then self repairing, is close to zero. Believing the story is forgiving, loving, but isn't likely how it happened.

+1

Also, unintended acceleration within the drive by wire system does not exist, it is user error.

 

[Tools R Us]

... The only thing even remotely possible (as far as I can tell) is a stuck throttle cable.

Maybe, but, it will only stick in a position where it has been operated. Who would mat the throttle to start the rig and back it out of the drive? Most would only use a small fraction of the available throttle for that, so a stuck throttle at a small opening wouldn't be a big deal.

 

[Frankencruiser]

Yeah, I agree. The more I think about it the more I am convinced that is the only possibility. Like you said, even if the transmission shifted into second with the torque converter locked the brakes would just overcome the engine and kill it. If the brakes failed they wouldn't spontaneously come back, so the only possibility left is no brakes were applied. This has to be a case of operator error.

 

[Tools R Us]

... To the op: while events like these are recorded for virtually every vehicle made, they are almost all operator error. Even the batch of "unintended accelleration" events toyota had last year were determined to be operator error. ...

+1

Also, unintended acceleration within the drive by wire system does not exist, it is user error.

Agree, but there have been a few issues on drive by wire systems (various brands) where they have failed at part or fully open throttle. Still not an issue, simply applying the brakes, turning off the ignition or shifting neutral solves the issue. The "unintended acceleration" thing is a great way to cause drama, get lawyers involved and maybe get a big payday from a big company, all things that some Americans love?