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Mark G
Mark G, Retired Toyota Technician
Category: Toyota
Satisfied Customers: 44
Experience:  ASE Master Certified Technician
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It sometimes stays in low. 92 previa altrac LE, I took the

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It sometimes stays in low.
JA: What is the model/year of your Toyota?
Customer: 92 previa altrac LE
JA: Are you fixing your Previa yourself? What have you tried so far?
Customer: I took the bottom of the transmission, removed the shift valves and checked their resistance. They looked good.
JA: How old is the transmission? Have you noticed any leaking?
Customer: It has a replacement pan. the fluid was high for a while
JA: Anything else you want the mechanic to know before I connect you?
Customer: I am now suspecting the engine speed or road speed indicators or the control box. I am not sure of the right code reader for this car.

Read the codes like this.

http://www.ryanjameson.com/toyota.html

Customer: replied 8 months ago.
Thanks,
I printed the table and i will try it tomorrow.
This seems to be an intermittent problem.
When it is occurring the shift indicator light for L stays lighted even when the car is in D.
Does this point to something specific?

That transmission selector switch may be bad.

Customer: replied 8 months ago.
It might be, but when it won't shift up, it lets the engine go back to idle when you let off the gas.
If it is in L then it does the engine braking function.
The path i see is engine speed and road speed sensors to wires to control unit to wires to transmission.
I will try the code readout tomorrow.
Thanks,

If you have the selector in drive then the L should never be lit up.

Customer: replied 8 months ago.
I know, but it happens when the shifting problem happens. I'm thinking that might point to the control box or the sensors. What do you think?

Found another post with your problem from years ago. No solution tho.

Happens on/off for past 4 months. The shift indicator lite shows both "D"
and "L" and will not shift out of first (shifter is in "D").
Lite displays "P" and "L" when turning key on, engine not running.
Disconnecting the connection to the TPS does not change it either (thought
it was known TPS issue with Previa's).
Goes away after a while by itself and all is fine for a while.
Any help appreciated.

And a follow up. Doesn't matter which gear I put it in, it stays in first with the light on
the shift indicator indicating "L" and whatever gear I actually select
(P,R,D,or 2), kinda shows that its in 2 gears at the same time.

With just the key on "acc" (engine off)it also does this.

Once, I was checking the connections to the ECM when this occurred and it
went away for a couple weeks.

I thought I narrowed it down to either the wiring to the TPS or the ECM
itself.

This car is old and that selector switch is simple. Nothing should be lighting that unless there is internal switch problems.

Customer: replied 8 months ago.
Mark,
This is way cool.
The check engine light blinked 27, which is a sub oxygen Sensor error.
What is this?
Could it cause the CPU to not send the shift signal to the transmission?The Oil Level light was also blinking.
It did two groups of 3.
There isn't a 33 in the table you pointed me to.
What do i make of this?
Thanks,

You must have an o2 sensor behind the catalytic converter. What it does is tell the engine computer how the cat is working. No relation to the transmission shifting. The oil level light is referring to the oil level. Did it stop doing that?

Customer: replied 8 months ago.
The O2 sensor error could be old.
I reset the codes by disconnecting the battery.
Now the CEL blinks 10 times and the Oil level blinks once.
I assume this is the no code condition.
I will see if any codes come up, if it fails again.
It is working perfectly now, the shifting is smoother than ever, probably due do the fluid being changed three times in the last year.
I guess the only thing that i would like now is the blinking codes for the 92 Previa.
The Previa was a premium vehicle, and probably has a more sophisticated CPU.
Do you have a reference for them?
Thanks,

10 is starter signal. You can do this instead of the battery.

  • Remove the EFI fuse (15A) for 30 seconds with the ignition switch OFF to clear any codes. It may take longer than 30 seconds, depending on ambient temperature (the lower the temperature, the longer the fuse must be left out).
  • You have a California Previa. I don't have a book on them any more.

Is this what you mean by blinking codes.

http://www.troublecodes.net/toyota/

Don't forget to rate me.

Customer: replied 8 months ago.
The EFI fuse reset worked. Now the CEL blinks, and every 10 blinks the Oil light blinks and if the OD is on the OD Off light blinks as well. I wish i knew more about the errors that they could report.
In any case there were no faults discovered that would be relevant to the shifting problem.
The car is working now, but i am worried that it could fail again, since i didn't actually fix anything.

Does this blinking only happen when you do the jumping of the TE1 to E1. In the diagnostic socket.

Customer: replied 8 months ago.
only when jumpered

I think you are having fun with that.

Customer: replied 8 months ago.
it is fun.
The question is whether I dare drive the van to work. It is 65 miles, so driving home in low is not a thing I want to do. I wish I knew what caused the failure.

I would price a new or used trans selector switch they do go bad.

Mark G and 2 other Toyota Specialists are ready to help you
Customer: replied 8 months ago.
Ok, thanks for your help.