Bertman
New Member
- Messages
- 7
- Location
- Diamond Bar, CA USA
Ok, so my 1992 SC400 has had issues with the trans since I bought her. Hopefully someone here can confirm to me that my issues are in fact related to the notorious shift solenoids.
In open loop operation, the transmission smooths flawlessly. No issues at all.
However, when the engine reaches closed loop temperature, the transmission randomly begins to lug the engine as if the torque converter locks up too early (highway driving and city driving). I have to manually shift down to 2 to have some decent acceleration.
Also, when I accelerate from a complete stop, it occasionally lugs the engine while shifting from 1st to 2nd. Feels as if the torque converter is locking up too early and I then too have to downshift into 2 to be able to accelerate. This occurs with Overdrive both on and off. I also would try to turn off overdrive whenever I would experience these issues to try to get it to downshift during highway driving and it does not disengage. Feels as if the torque converter is still locked up (possibly some sort of fail safe mechanism???)
The Overdrive light would flash when I would experience these symptoms until I adjusted the throttle position sensor. The transmission would also slam hard into Reverse and Drive on cold start ups. I did research on that issue and found out about adjusting the Throttle Position Sensor, which sort of cured my cold start transmission gear slamming. Now ever since I've done that adjustment the transmission has still had its shifting issues, but the blinking Overdrive light is no more. I have checked the ECU for transmission codes but none are ever found.
Other issues are also occasional late 1-2 shifts (revs up to about 3500-4000 rpm before it shifts. ECT PWR is off.)
So my question is, do my symptoms justify the replacement of the shift solenoids? Any steps to confirm that the solenoids are no longer any good (such as checking resistance?)
I'm inclined to open up the oil pan and service the transmission without replacing these solenoids only to find out that the solenoids are indeed toast and have to perform double labor.
In open loop operation, the transmission smooths flawlessly. No issues at all.
However, when the engine reaches closed loop temperature, the transmission randomly begins to lug the engine as if the torque converter locks up too early (highway driving and city driving). I have to manually shift down to 2 to have some decent acceleration.
Also, when I accelerate from a complete stop, it occasionally lugs the engine while shifting from 1st to 2nd. Feels as if the torque converter is locking up too early and I then too have to downshift into 2 to be able to accelerate. This occurs with Overdrive both on and off. I also would try to turn off overdrive whenever I would experience these issues to try to get it to downshift during highway driving and it does not disengage. Feels as if the torque converter is still locked up (possibly some sort of fail safe mechanism???)
The Overdrive light would flash when I would experience these symptoms until I adjusted the throttle position sensor. The transmission would also slam hard into Reverse and Drive on cold start ups. I did research on that issue and found out about adjusting the Throttle Position Sensor, which sort of cured my cold start transmission gear slamming. Now ever since I've done that adjustment the transmission has still had its shifting issues, but the blinking Overdrive light is no more. I have checked the ECU for transmission codes but none are ever found.
Other issues are also occasional late 1-2 shifts (revs up to about 3500-4000 rpm before it shifts. ECT PWR is off.)
So my question is, do my symptoms justify the replacement of the shift solenoids? Any steps to confirm that the solenoids are no longer any good (such as checking resistance?)
I'm inclined to open up the oil pan and service the transmission without replacing these solenoids only to find out that the solenoids are indeed toast and have to perform double labor.
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