93 SC300 NOT SHIFTING

1993 Lexus

Tiny

jsandbeck1

October, 20, 2007 AT 8:40 PM

I have a 93 SC300 that I bought as a repairable. Ever since having the battery die for a long period of time the car will not shift by itself. Every time I get to a stop sign or stoplight I have to put it in 1 and then shift it myself. I am wondering if this is something that can be reset or if it is the tranny going out. It worked before the battery going dead which makes me think it is just something that needs to be reset within the computer or something.

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Tiny

TomWoodLexus

November, 3, 2007 AT 10:08 PM

I am currently having this problem with my ES300. But I had a code, it was for the shift solenoids. I ended up finding excessive resistance in the connector at the computer. I took the two pins out that apply power to the solenoids, and I also had soldered the connections, I chinked the connector up before I learned how to take the pins out like a pro, and today it stopped shiting again. Do you have the engine light on with the overdrive light flashing?

Tiny

jsandbeck1

November, 4, 2007 AT 8:15 AM

I have no lights on as far as overdrive lights or check engine lights so it is kind of weird

Tiny

TomWoodLexus

November, 4, 2007 AT 9:39 PM

Hmmm. Ok. Now, when you shift by hand, does the transmission skip any gears? My ES has L 2 and Drive. When I go to 2, my tranny skips second and goes straight to third.

If the other gears work fine and feel good, your problems is most likely the shift solenoids. Either the circuit is faulty, or the solenoids are bad. The way to diagnose this is to test the resistance in the solenoid circuits. You will have to back-probe the ECM for each of the shift solenoids (2 of them) and ground, and your resistance should be around 12-16 ohms. Then check the resistance between the front of the connector, and pierce the wire with the lead one inch down the backside of the connector. It should be 0 ohms. My connector was the culprit for me. Although it is pin replacement that does the trick, and if it is all good, than you need a new ECU. But if you didn't have a code, I wonder is the solenoids are just blocked up with too much particulate matter?

Try some drain and fills too, work the tranny with 2 drain and fills over a few thousand miles, let the tranny get used to the new fluid (seals tend to leak alot with a flush off the git) then after another few thousand miles, go for the flush!

Tiny

jsandbeck1

November, 5, 2007 AT 3:04 PM

I will give it a try and post my results when completed

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