tranny issue?
12-02-2009, 12:44 PM
#1
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tranny issue?
hey guys, im not new to the site, have been on here for awhile now, but just made an account.
i have a 91 3.0 sr5 4runner. its auto, and seems to possibly need pressurized or something? im not sure what it needs or if infact the tranny may even be going out, but it shifts randomly in and out of overdrive while on the high way, sometimes when i floor it, it takes what feels like minutes to downshift, and other times downshifts when i dont want it too, and it doesnt have too.
thirdly, it is either 2nd or 3rd that until the runners fully warmed up will not shift past the first 2, or 3 gears. any help or suggestions? thanks
i have a 91 3.0 sr5 4runner. its auto, and seems to possibly need pressurized or something? im not sure what it needs or if infact the tranny may even be going out, but it shifts randomly in and out of overdrive while on the high way, sometimes when i floor it, it takes what feels like minutes to downshift, and other times downshifts when i dont want it too, and it doesnt have too.
thirdly, it is either 2nd or 3rd that until the runners fully warmed up will not shift past the first 2, or 3 gears. any help or suggestions? thanks
12-03-2009, 05:27 AM
#3
Registered User
Howdy neighbor, welcome! I would check the Engine Coolant Temp sensor, the Thermostat, and the Throttle Position sensor.
The engine coolant needs to be 158F in order for the computer to allow the tranny to be in O/D. If your thermostat is stuck even partially open, or the ECT temp sensor is not reading correctly, the computer may take the tranny out of O/D. This may happen more often on the highway as the increased airflow cools the coolant. Keep in mind that having a truck that will not shift into O/D until warm is completely normal. If however it takes a extended period of time for the vehicle to shift into O/D check those two items.
As for the delayed downshift, check the Throttle Position Sensor. If the computer is receiving inaccurate TPS info, the shift points may be off. The TPS could simply need re-adjusting, or it may be faulty.
The Thermostat can be checked visually of course. I have seen some Toyota OEM thermostats that had the jiggle valve stuck into the thermostat valve not allowing the thermostat to close fully.
The ECT can be checked with a multimeter. There is a graph availible for different resistance readings that you should see with corresponding temperatures.
The TPS can also be checked with a multimeter. You should see a steady voltage increase with an increase in throttle opening.
There is a sticky to a FSM up at the top of the page. It should have the info you need to test the ECT and TPS sensors.
I don't think you have a mechanical problem with the tranny. This would be evident by slipping during gear changes, or certain gears not working at all. I did not see that in your description of the problem. If an electronic tranny shifts erratic, but the shift points are firm and positive, the problem is generally not mechanical, but electrical.
The engine coolant needs to be 158F in order for the computer to allow the tranny to be in O/D. If your thermostat is stuck even partially open, or the ECT temp sensor is not reading correctly, the computer may take the tranny out of O/D. This may happen more often on the highway as the increased airflow cools the coolant. Keep in mind that having a truck that will not shift into O/D until warm is completely normal. If however it takes a extended period of time for the vehicle to shift into O/D check those two items.
As for the delayed downshift, check the Throttle Position Sensor. If the computer is receiving inaccurate TPS info, the shift points may be off. The TPS could simply need re-adjusting, or it may be faulty.
The Thermostat can be checked visually of course. I have seen some Toyota OEM thermostats that had the jiggle valve stuck into the thermostat valve not allowing the thermostat to close fully.
The ECT can be checked with a multimeter. There is a graph availible for different resistance readings that you should see with corresponding temperatures.
The TPS can also be checked with a multimeter. You should see a steady voltage increase with an increase in throttle opening.
There is a sticky to a FSM up at the top of the page. It should have the info you need to test the ECT and TPS sensors.
I don't think you have a mechanical problem with the tranny. This would be evident by slipping during gear changes, or certain gears not working at all. I did not see that in your description of the problem. If an electronic tranny shifts erratic, but the shift points are firm and positive, the problem is generally not mechanical, but electrical.
01-02-2010, 07:59 PM
#5
might read this
http://www.toyotaholics.com/support/...sp?TOPIC_ID=19
http://www.toyotaholics.com/support/...sp?TOPIC_ID=19
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