kapilhh

I've a 99 Lexus ES 300 that has an automatic transmission. I would like to convert it to manual shift - i.e. use the existing auto transmission, but shift it manually, by switching on/off the solenoids. I am new to working on transmissions, so please advise if it is possible. I got to know that Solenoid 1 and 2 are switched on/off when gears are changed. eg: 1st gear Solenoid 1 is ON and solenoid 2 is OFF, for O/D both are OFF etc. However, my car has 5 solenoids - SL1, SL2, SLT, DSL and S4 (I'll try to attach the diagram here). Is Solenoid 1 and 2 the same as SL1 and SL2? Will I need to control the other solenoids if I have to shift manually? Should I take care of anything else?

PFB

That doesn't sound like a good idea at all. It's a computer controlled transmission. You'll make it not drivable, and probably ruin it.

kapilhh

Yes, it's a computer controlled transmission. The computer gets input from sensors (crankshaft rpm, throttle position, transmission speed etc.) and its output is only through solenoids (I think?!) If I disconnect the connection between solenoid and computer, then it can't control the transmission. I would switch the solenoids on/off manually. I understand that I will get some trouble codes related to transmission. Some of them I may be able to get rid off. eg: If I disconnect the solenoid, then I think there is a solenoid not found or something similar error, when I turn on the ignition. I read online that the solenoid has a 12.5 ohm resistance and since the computer doesn't get it, it gives the error. If I add a 12.5 ohm resistor I may stop the code. There would be other errors since the gears are shifting not based on the algorithm in the computer. I don't know how to get rid of that. But the computer may not be able to take any corrective action without access to the solenoids (correct?). So the car should drive fine, even with these codes.

I'm not worried about making it not drive-able as it already is not drive-able :-)

What other problems do you think I will run into? and the solutions too :-)

ES300NZ

I see what you did there, .. if you do this the ECU will think the g/box has a fault and go into limp mode. (no power, low rpm limit) ...

why not just fit a manual transmission or get another car. really, a smooth auto trans is the best part of this car, it's relaxing to drive.

Why do you want to do this ? what caused you to bother to think about this.

jo8594

If you don't care too much about the car, sure go for it. Never hurts to try something new. I just wouldn't have high expectations that it will work.