Mechanics

HOW ???

1991 Toyota Previa • 255,000 miles

I do not know what the problem is, but it is in fact that after the sensor is cleaned idle speed switch gears started earlier than you need. And it does not depend on how I hit the gas pedal. The 2nd gear is switched to 25km/h, third in the 45km/h, 4th in the 75km/h. And before that it depends on how I hit the gas pedal. We changed the idle assembly with a sensor, in place on the used. But the same result. Thank you for help.
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Vali
March 7, 2012.



If you had an earlier question, you should reply to it so that whoever attended to you can response when notification ism received. This would keep the history of what had transpired in one thread for easier reference.

What sensors did you replace?
Is the MIL indicating?


KHLow2008
Mar 7, 2012.
First clean VALVE ASSY, IDLE SPEED CONTROL(FOR THLOTTLE BODY) and then change THROTTLE Assy with SENSOR, THROTTLE POSITION.


Tiny
Vali
Mar 7, 2012.
Is the MIL indicating?

Try the following.

SHIFT POINTS TOO HIGH OR LOW

1. Warm engine to normal operating temperature. Connect voltmeter between terminals "T" and E1 of check connector. See Fig. 8. Check connector is located on driver's side. See Fig. 1.

2. Turn ignition on. Note that voltage changes with throttle opening. If voltage changes with throttle opening, ECT ECU or transmission is defective. If voltage does not change with throttle opening, proceed to next step.

3. Obtain access to ECT ECU. Connect voltmeter between terminals
STP and E1 on ECT ECU with connector installed on ECT ECU. See
Fig. 12.

4. No voltage should exist with brake pedal released. Approximately 10-14 volts should exist with brake pedal depressed. If voltage is not correct, check for defective brakelight switch or wiring circuit.

5. If voltage is correct, check for short or open circuit in wire to "T" terminal of check connector. Check for defective throttle position sensor or wiring.


KHLow2008
Mar 7, 2012.
First thanks for the extended response. MIL light is not lit, and in general all the indicators are normal. Gear changes are very early and all the problem occurred after cleaning. The remaining items will check after work and write the results.


Tiny
Vali
Mar 7, 2012.
Hello. We detect the problem. The problem is in throttle postion sensor connector. Where one of the cables is destroyed. We repair it. But there is have another problem all shifts are normal but in normal condition the rear gear is normal too. But in load car is not going. Thanks


Tiny
Vali
Jun 14, 2012.
I mean in load car is not going to rear, but front gears is normal in load.


Tiny
Vali
Jun 14, 2012.
If you mean you arenot able to reverse when loaded. You need to get the transmission tested. The trans could be slippig. Have you checked the transmission fluid level?


KHLow2008
Jun 14, 2012.
Yes exactly. Reverse gear only works on ground level, while running the car in descent, does not go back to the top with the revers gear. We changed the oil, oil is in level, have changed the whole overhaul kit (seals, gaskets, clutches and discs), but the same result.


Tiny
Vali
Jun 15, 2012.
Something is wrong with the repairs. Get a line pressure test done to check if you have sufficient pressure when reverse is engaged.

Was this the problem for overhauling the transmission?


KHLow2008
Jun 16, 2012.
This problem was to repair. But after repair problem has not changed. And another problem was but it increased after the repair. The car jerks when shifting between gears in a smooth motion. But under hard acceleration is no problem. And it is highly expressed after the 80km/h As if the machine is confused between the gears.I have not checked the pressure, and what could be a problem if the pressure is not normal? Or maybe the problem is not in the gearbox and what that Electonics. Because when we dismantled the gearbox all the details except the clutch were perfect. Thanks for help
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Tiny
Vali
Jun 19, 2012.
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