Kdiehm

Hello I am new to this, but I am very interested in learning somethings about my car. I just purchased a 1990 Lexus LS400. I am a woman but know a few things about cars, except this one. I am stumped. It is an automatic transmission and when I am driving the care doesn't seem to want to shift into 3rd or 4th gear. My RPM's register at 4K-5K and the car still won't shift into I believe 3rd. I tried releasing the acclerator thinking it may shift, but the rpms and speed drop and then when I apply the acclerator the rpms go back up. whats going on?

emarknot

https://www.clublexus.com/forums/sc-...placement.html


this comes to mind

deanshark

Is there any codes showing up, meaning is the O/D off light flashing or staying on constantly? If so check for codes, if you get codes 63 and/or 67 then you might want to check out that link and change the solenoids. If not, don't just go changing parts you don't need. You might just need to flush the transmission fluid, not a power flush. This is how; http://www.lexls.com/tutorials/trans...ransflush.html

Kdiehm

Thanks for the info. I have hooked it up to a machine yet, so the codes are unknown at this point. But the O/D light does not flicker or stay on. I just took it for a drive on the highway and opened it up a little bit and it seems to be shifting better. I am wondering because of the O/D button if it is pressed too much over the years if it has a problem staying engaged. I dunno but thanks for the info and I'll check it out.

steve2006

You don't need a code reader on a 1990 LS400 just a bent paper clip and follow the tutorial link below.
The transmission will not shift from 3rd to 4th ( overdrive) until it has reached normal operating temperature so this is not a fault once you get 3rd to engage.

http://www.lexls.com/tutorials/intro/codereading.html

deanshark

Hate to disagree with you but it does go into overdrive while still cold. What do you consider normal operating temp? I can go out on the coldest mornings (in winter) start the car, 20 seconds later take off on the main road and it goes into every gear. Not that I do that all the time, I usually sit for a couple minutes to let the fluids circulate before leaving.

Kdiehm

I used the diagnostic trick and got a code 31 on the engine and nothing on the transmission. I looked up the engine code and it is an air flow meter signal. But I still do not understand what this has to do with the shifting of my car.

deanshark

That code wouldn't have anything to do with shifting. Actually, I've never seen the code 31 come up without also having code 24 along with it. I would suggest clearing the codes, (like it says in that link) and check it again after a couple days to see if it comes back. I think it wont. I still think if you flush the tranny fluid it might take care of your shifting problem. Or have the filter changed and flush it after, it might be the original filter. How many miles on the car?

vaughn37

I read a bad throttle position sensor will cause shifting problems also

Kdiehm

I have one last question...is there electrical problems with this year and model of lexus. My car I have only had a week and drove only in town because of the shifting/not shifting problem. Now I thought I linked it to a short in the dash with the dash light dimmer switch. But then today the car just started to lean a little farther down on the drivers side and it sounded like I had a flat tire. I wonder if this car was a good idea...and suggestions?

PureDrifter

iTrader: (10)

http://www.lexls.com/tutorials/lighting/bulbout.html