kpopil

I have a 2000 RX300 AWD with 126,000 miles on it. I was driving to work when I noticed my transmission wouldn't shift into overdrive. I was traveling about 60 mph at the time. The car was still going 60 mph but my rpm's were high (between 3 & 4 thousand). It finally shifted and that was that. It did it a few more times so I took it to a shop. They said the transmission needed rebuilt. At an estimate of $2,300, I decided to get another opinion at a transmission shop. I was told my transmission is fine. The mechanic said the fluid doesn't smell burned and it's shifting like a dream. He told me that transmissions are stupid and only do what they're told. He said if the engine isn't right on, then the transmission may not work properly. I have noticed a sound that almost sounds like a squealing noise when I start the engine, only it doesn't go away. And now it sounds as though something is almost ticking. The first mechanic didn't say anything about it. The transmission specialist said he listened with a stethoscope and it sounds like the timing belt might have issues. So my question is, can the timing belt have anything to do with the transmission? And if not, what would cause the transmission not to shift? Is there a sensor or something I should consider looking into? I've heard of the knock sensor causing this but I wouldn't know so I thought I'd ask the experts. And my husband is somewhat mechanically inclined. How hard is it to change the timing belt? Please help.

lexus114

As far as the noise coming from the vehicle,it could be a lot of different things. I.E,water pump,altenator bearing,timing belt tensioner bearing, Could even be your transmission torque converter. As far as the trans. have your husband drain the oil,drop the pan,replace the filter in their (preferable the mesh screen type) and see how things are looking in their. As far as the noise,its like I mentioned above, you may need a shop to try and diagnose that. unless your husband can try and check the things I mentioned. Also, make sure your engine has enough motor oil in it. The not going into over drive could be temperature related, the next time it does this,look at your temperature guage, if its not warmed up enough,it will not shift into overdrive. Are their any instrument panel lights on? such as your check engine light etc.? If your engine light is on,it wont shift into overdrive either. I hope this will help you out,let us know what you find.
rm

kpopil

Yes, the check engine light is on. I did check the oil and it was very low. I hope I didn't do something to the engine. The oil level was low but I had the oil changed about 1,000 miles before I checked the oil. I didn't think it would be low that soon. And since then, I've changed the oil again (just last week at the shop). The guy at the first place I took my car did drop the pan on the trans. He said there was metal pieces and the fluid was burned and I needed the rebuild. That's when I took it to the transmission place.

My husband thinks it may be the torque converter too. I'm going to take it up to Auto Zone today. I'll post the reading when I get home from work. Maybe you can help me with it. And thank you for your help! This forum is great.

AlexusAnja

WAIT A SECOND HERE !!! You have a CEL, and with the transmission shifting strange, you or your husband did not think the two were related? The "check ENGINE light" isn't literal to say it's just an "ENGINE" problem, is the whole mechanical powertrain monitoring, from engine, to transmission to emissions. An oxygen sensor out would trigger the light too.

Also, if you say the first guy dropped the pan and saw there were bits and needed rebuilding...unless he just put the pan back on with the old fluid, of course the second guy would say it's fine because there is fresh fluid in there.

Unless the issue is the "cold temp" shifting that the RX is programmed to do (before reaching normal temp. the computer retards the O/D to help the engine warm up faster) then there is something wrong with the transmission for sure. The low engine oil, or timing belt, will not throw your transmission off.

lexus114

actually,the delayed shift (when cold), is to heat up the converter`s.(gets them at the operating temp. faster) It`s all an emissions thing.

kpopil

I made the appointment with the first shop when the light came on. I had to wait a few days before they could get me in. That's when the transmission didn't shift properly. This is all very recent. I'm not driving it right now so I don't do any damage to anything else. I'm going to run it up to Auto Zone in a bit which is about a mile from my house to see what the code is. The transmission guy had reset the engine light and it stayed off for almost a day but it's back on so I parked it.

AlexusAnja

Hopefully it's not anything major, but the RX300 (unfortunately) has not has a sterling reputation with it's transmission. Knock on wood, mine is about 120K and going strong. Hopefully yours is just that "cold running" in the beginning (you are in Ohio, so you do have real winters) the RX does and the CEL is for something minor.

mikey00

The check engine light being on could be any number of things from a bad sensor to a hose off to a loose gas cap. In fact I know you said you just had the car serviced. It is a common problem that when they lift up the top of the air box to check the air filter the evap hose gets pulled off from below and causes a check engine light. First thing to do is to get the code read which will give an indication of possible causes. That being said, nothing is wrong with your trans. When you have a check engine light the ECU prevents the trans from shifting into overdrive. This is by design. Fix the check engine light and your trans will shift ok. You could reset the CEL by disconnecting the battery or pulling the EFI fuse and you will see your trans shifts ok, until the CEL comes back on. Once this is taken care of, move on to doing preventive maintenance to clean up the trans fluid and pan.

mikey00

I bet it shifted into overdrive just fine until the CEL came back on.

kpopil

I stopped by Auto Zone and this is what the paper says:

OEM Number to Cross: P0768

Definition - Shift solenoid D electrical malfunction- SSV S4
Probable Causes
1. Open or short circuit condition
2. Poor electrical connection
3. Failed SSV S4

What is an SSV S4?

This is the only code it's giving. Any advice?

And Mikey00 - You are correct in that it shifted into overdrive just fine until the light came on.

salimshah

The solenoids actually do the shifting.

Your on board computer has done the diagnosis for you. A mechanic can measure the resistance of the sensor and determine if the sensor is bad or there is a problem with the connectors or the wires.

I can't tell if this sensor replacement is a DIY or not.

Salim

mikey00

The ECM is detecting a failure in shift solenoid D. This is not good. I have never heard of anyone successfully doing a DIY repair on this code. Usually a shift solenoid is not replaced by itself. The whole valve body is usually changed out. The solenoid is part of this valve body. What is ironic here is that it is not the bad solenoid that is preventing you from shifting into overdrive. It is the fact that the ECM is detecting a failure, same as many other ECM detected failures which are more easily fixed, that is preventing the shift. I don't think you will find a shop that will just do the solenoid/valve body repair. Most will want to rebuild the tranny which may be more cost effective and better in the long run. Use the search function in this forum and search for "P0768" to see what others have experienced with this code. Here is one:
https://www.clublexus.com/forums/sho...ighlight=P0768

sktn77a

iTrader: (2)

I would take it to a Lexus dealership and get a second opinion. Usually, the transmission O/D problem is secondary to an engine problem (O2 sensor, coil, etc). If it truly is what the Auto Zone code says, it sounds like an expensive transmission replacement.