weinerface

I tried deleting my other post but I cannot figure out how, sorry for the double post I just wanted to fix the title.

Hi all!

so my 92 SC400is having some major issue and I cant figure it out

car starts and runs and drives perfect for the first couple miles. Then no matter what gear or speed it seems like the transmission throws itself into 1st gear. (RPM goes to 5k+, loss of power until i slow down to 10mph or so) at this point it will drive but will not change gears and will only go 10-15mph or so.

Heres the tricky part...a

If I shut the car off and wait 10 seconds I can turn the car on, put it in drive and it shifts and drives fine for another few miles then does the same thing. (I can repeat this for as long as I need to)

Tried:
1. replacing ECU with a working one from a friends daily driver (same model and ecu part number) = same symptoms
2. No transmission error codes present,
3. CEL shows #13 RPM Signal no2 fail = could this be it?
4. checked fuids = all is fine
5. O/D on and off as well as "L" and "2" gear = same symptoms
6. reverse works at first then stops working when the tanny does its thing but works again after restarting car.


This is driving me insane! at first I thought it was the capacitor leak issue, ruled that out i think. now the CEL #13 code makes me thing it would make sense considering it has to do with my RPM. but then again other people have that code and dont have my symptoms. There is a clear cut recognisable pattern of symtoms to my issue, but no matter how much I search or look I cant find anyone with a resolution or even an idea what it is.....

any help would be greatly appreciated!

SC400slide

iTrader: (11)

How many miles? Any rodents living in the engine bay or firewall? They'll chew through wiring harnesses like they're going out of style.

weinerface

200K miles
no rodents i practically live in the engine bay lately with all the work ive been doing...unless im a rodent ...lol

im thinking its either the shift solenoid or the error code. although neither problems produce these symptoms for others. the car was working fine, so its something recent that has gone awry....im lost...im so hesitant to take it to mechanics because I almost ALWAYS get ripped off especially living in las vegas, and being as I just moved here last month I dont even know a soul out here to ask for help...

SC400slide

iTrader: (11)

Is it running rough at all at any time? Code 13 usually refers to either a Cam position sensor or that the timing belt skipped a tooth...wouldn't explain the tranny issues though.

Read this: https://www.clublexus.com/forums/per...pm-signal.html

Your RPM could be completely different than the trans issues. What colour is the ATF?

weinerface

my timing bet is really worn and cracked, i have the belt i just havent had the time to change it, from what ive read its a pretty crappy job.

the ATF is red and when it does shift it shifts nice and smooth no issues at all. and the idle used to drop and make the car die when I wouls stop when I first got the car but new plugs fixed that it idles fine now.

i did notice a tear in the jacket on one of my plug wires. i just got back from picking up a new set of wires im going to swap them out although I dont suspect it will fix the issue.

weinerface

put on new plug wires (already did plugs last week) no change
.....figures lscowboyls isnt around anymore :/

weinerface

no one has heard of this before? thats crazy to me lol. i cant wait to figure this out and contribute a little here

I had a mechanic look at it early this morning. they basically said tranny is lunched yet couldnt explain the symptoms (to me thats not good enough to warrant replacing the whole transmission) not yet at least. me best idea is its something electrical im spending the day retracing the harness from the ecu to each of the components hoping to find something.

worst case and I do need a new tranny, i know they are cheap so thats not an issue, i tried searching but all i can find is tutorials on swapping for a manual. (not a fan of manual transmissions, i have my reasons) does anyone have a link for just straight swapping an auto tranny for another anuto tranny? not that big of a deal just nice to have pictures lol.

weinerface

****UPDATE*****

Per the toyota transmission service diagnosis manual i disconnected the harness connector to my transmission solenoids. basically making the transmission a half a** manual transmission. i can now shift perfectly from L=1st. gear....2=3rd gear....D=overdrive...got it up to 85-90mph no problem plenty of power tranny shifted like a damn champ! I was also able to downshift without a problem.

only one issue remains. when i come to complete stop "sometimes" it will stay stuck in first even if I shift it to another gear. if i keep it in "2" at a full stop, its obviously a slow takeoff but i can get up to speed and shift up no problem, if it does stay in 1st gear i can literally throw it in neutral cycle the ignition throw it in gear and i can shift like normal again.

im so close to fixing this, just hoping this puzzle pieces can help someone help me figure it out.... im even willing to put up a reward for the person who helps fix this....

SC400slide

iTrader: (11)

https://www.clublexus.com/forums/per...placement.html
^Have you not tested/replaced the solenoids yet?

weinerface

solenoids was one of my next steps. i drove it extensively last night to really get a feel for the transmission, after a while i think i can tell there might be something slightly different. lets say i drive from a stop and get into 3rd gear and just druise for a while....ONCE IN A WHILE it will feel like it slips into neutral (car revs but literally no power) however i can literally put it in neutral cycle the ignition put it in drive and keep going.......neutral safety switch? stop switch? tranny really is effed?

so ive gona out a few times now and found that it only does it when im in a gear higher than 1st and i come to a stop quickly... (i.e. coming to a stop sign) kind of leads me to think the torque converter? but everyone I asks says thats the last thing that would fail.... im not so sure


i strongly think its something elecrical i just havent been able to afford a new multimeter yet.

at least my car is semi drivable now, just not very healthily lol im going to replace the slenoids as soon as i can.

Also, if it was my solenoids to begin with would I be getting a code for that?

weinerface

so after having the solenoids disconnected and reseting the ECU i dropped the ATF fluid from the pan and it was dark. (it was cherry red few days ago) i refilled with a couple quarts to replace the fluid in the pan and now it shifts PERFECT and has not got stuck in gear one time. maybe the filter? was thinking maybe its like the fual pump on my old camaro, everytime i would stop it would die, the screen on my fuel pump was clogged when i would stop it would jam it up and the car would die but start right back up.

grabbed a new filter and gasket, gonna replace it today and check the fluid color again.

(so far its more fun shifting my car manually without a clutch too lol)

Im sure this means my trans is gonna blow up in the next couple weeks, Im sourcing one locally for $200.... I will keep an eye on it and see what happens.

just wanted to update and put in a big thank you for the help!

any additional ideas would be appreciated of course lol

SC400slide

iTrader: (11)

Something else I did forget to mention is that how crucial it is to fill the transmission up with the vehicle running at idle. The TC must be able to circulate the fluid throughout the entire case of the tranny...if you're not doing this, chances are it could be your issue. I burnt up a tranny before because I didn't fill the tranny with fluid whilst running the engine. Make sure you are running the engine as filling.

Good luck!

weinerface

wtf? now this i did not know.....ok i will do that today. thanks so much!

SC400slide

iTrader: (11)

Now that I think about it, it might not be as necessary to do so because the tranny was never 100% drained of fluid. It still would be a good idea though.

weinerface

**UPDATE**

ok so i dropped the pan (full on expecting to find a metal mess) replaced the filter and added new fluid. reconnected the solenoid harness. guess what?

no metal (a little glitter but nothing dramatic at all!) drives fine now. im going freeway testing tomorrow to check for sure, but car shifts fine now and i even drove it hard for a minute and no slipping, no getting stuck in gear, just driving like normal. I cant believe it was the damn filter....

thnank you so much for your help! next its onto this damn code 13 CEL. (my timing belt is worn to hell so im pretty sure thats it)