RedSTi

Hello everyone! I have done quite a bit of searching in the past few weeks about some problems I am having, but I can't seem to find anything that answers what my car is doing. Maybe I'm not using the right key-words or something, so I'm really sorry if there is already a thread fixing this problem. I have a 1998 Lexus GS400 that I recently purchased knowing there was a transmission problem. I wasn't worried about the transmission since I was buying the car for parts, but now I want to fix the car. When the car is running in park, it tries to pull forward a bit like it is in a high drive gear. It doesn't sit still. Neutral is the exact same way as park. Reverse just simply does nothing at all, no driving backward, no driving forward. All the rest of the gears act normal, even in manual mode, aside from the car seeming to be in a lip mode. It doesn't rev past 4000 rpm, and it seems extremely loaded down or like it is bogging, even when raised on jackstands and not driving anywhere. When I first turn on the car, there are no light on the dash, but due to a brake line leak right in front of the right rear caliper, the brake light comes on in the dash. Shortly after that, the CEL comes on and a warning buzzer starts. I'm sure those are coming from low brake fluid since the leak is actually really bad (I need to get that fixed soon). Now for the interesting part. I had read on here that the transmission shift solenoids break a lot on these cars, and so had the previous owner. The previous owner put in all new shift solenoids, a new transmission filter, and new transmission fluid. That didn't fix the problem for him. So after I read that the S1/A solenoid could cause those weird gear problems, I pulled off the pan and checked the solenoid. I took out the S2/B solenoid as well just for reference since that one apparently worked fine. The S1 solenoid read at 12.2 ohms, and the S2 read at 13. Then I checked to see if they kicked out when 12v was applied. Both of them did kick out and retract perfectly fine. While I had the pan off, I checked for codes when the solenoids were plugged in and the car didn't have the CEL on, and there were no codes at all. Which was odd since my other GS400 brings up a code for a bad shift solenoid S3/C. So then I unplugged the S1 solenoid and checked codes again and sure enough, there was a code showing a S1 solenoid malfunction. Plugged it back in, cleared the codes and it didn't pop back up. While I was under the car I noticed that the ground strap that goes to the transmission bell housing was corroded and broken off, so I replaced that thinking it might help, or at least cant hurt. I put the pan back on, filled it with new fluid again, and the car had the same transmission problems, once again with no codes. After the CEL popped up from the brake issues, I scanned it again and it showed 12 Lexus specific codes, all of which were ABS or master cylinder related. (Side question, would those codes come from the brake fluid leak draining the reservoir down to empty? Or do I actually have a bad master cylinder?) I am at an absolute loss as to why the car is acting this way. The only thing I can think of is a bad ECU, but there are no other symptoms that point towards an ECU failure. Do I have a valve body problem in the transmission? I have a spare transmission that I know works that I could put in, but I don't want to go to all that work to find out that wasn't the problem. Does anyone have any ideas? Or threads that may point me in the right direction? Also, someone had mentioned in a different thread about limp modes that swapping ECUs to a known working ECU could help diagnose the problem. I could pull the one out of my other car to check, would that be a good thing to check?<br />Thanks in advance!

eicca

I only have advice on the transmission, but it sounds like the shifter linkage isn't hooked up right. That'd be the first thing I check.

Tuanville

Can you post all the codes?

06GS300Lex

Check engine light codes all lead to replacement of the solenoids.
P0761
P0756
P2757

Tuanville

These aren't the exact codes for your Codes, but its relevant and its for the 3uz-fe transmission. I would follow these procedures to check if its the ecu or solenoids. Here are some PDF that might help you, good luck.

TW99GS300

I agree with this. The indicator on the dash and the actual gear selector switch on the trans is off by 1 or more positions.

Scraape

best post award goes to this guy!! Haven't been able to find this **** anywhere, and i've had dealerships and my mechanic give me the wrong part numbers for the solenoids!!