NuclearSC

Hey all, I’m new to the forum. I was a mechanic at Lexus for 2 years and never really got to do much diagnostics, so I’m having trouble pin pointing my issues. I no longer work for Lexus so it’s difficult to get help with diagnosis.

I own a 1st 1992 SC300. It’s the 3 speed auto with overdrive. I’ve had an issue with what I assumed was my transmission at first because it didn’t feel like the trans was down shifting properly whenever it got warm. It has been extremely low power off of red lights but shifts fine after that. It’s only that 1st-2nd gear range I’m having low power in.

Recently I had a situation where my overdrive was kicking off and on violently and it only ever happened once. Just wondering if anyone else has this issue or heard anything about it. Idk if I should look into a new ECU for overdrive or maybe check transmission solenoids.

During the summer it was constantly bogged down when launching from a red light, even with my foot to the floor it just barely got up to speed. But recently since the cold weather is back, it shifts perfectly until it gets to operating temperature.

Sorry if I rambled too much, never posted to a forum especially about cars. I’d appreciate any and all feedback!

scsexy

iTrader: (1)

probly needs a trans... check the fluid level, do a flush or a few flushes and see if it helps.

Duck05

Would not hurt to inspect the ECU as well….. Strange symptoms from the capacitor leaks are common.

KahnBB6

iTrader: (5)

^^ This #1. Then after re-capping the ECU with correct spec and OEM brand caps move on to investigating the transmission if the issue persists. All SC300's and SC400's are at an age where if the ECU has not been serviced with brand new OEM spec and brand capacitors it should be as preventative maintenance.

Tanin Auto can handle this by special request unless you really know what you're doing with circuit boards to desolder, remove the old caps and install the new ones exactly as they came in, noting the polarities. Also if there is any electrolytic fluid that leaked onto the board that would need to be neutralized and removed. Any board traces that get damaged with that fluid need to be repaired with tiny jumper wires.

GAsc300

Hey there,

This doesn’t help much but that’s a lot like an SC400 I test drove this summer. 1992 maybe with 160k . Super sluggish between 20 and 55 mph. Pedal to floor and it took 20 seconds to get to 55 mph. Owner thought it was shift solenoids. I read enough about that to realize it seemed like an over complicated explanation but I couldn’t come up anything better at the time.

Clean Throttle body, clean egr maybe but can’t imagine that would account for too much

Kolbe