deepbluesk

I am looking for some ideas on what may be wrong. I have about 164K miles on the 99 RX300 AWD now. Changed the trany fluid & filter twice in the last few years with the correct Toyota fluid.

Just in the last few weeks, it's starting to act up. On occasion, when parked and put into rev to back out of a parking spot, it seems to hang up a bit (almost like the brakes are on), then jumps hard into gear.

I wonder if this is the Beginning of the End for the Trany .... or possibly something else in the AWD system. Any thoughts would be appreciated.

habeeb89

iTrader: (3)

I am thinking it's the tranny going, I would check the filter and drop the pan again. Maybe it's clogged up again?

salimshah

If the hard shift/hang happens on vehicle parked on an incline, I would not worry too much. If it is happening on flat surface, have it checked out.

Salim

JAB

The scenario you describe is exactly what happened to mine. Trans fluid change at 100K; transmission dead by 115K. The occasional delayed reverse engagement was the first hint of impending failure.

Lexmex

Were you also releasing the plug on the front differential to get the fluid out of there?

Although unrelated, when was the last time you changed out the gear fluid on the transfer case and rear differential (that can help the tranny on an AWD system)?

Are you noticing any thing odd in the gear switches when you're driving?

deepbluesk

all flat surfaces...

deepbluesk

Yes, drained the front diff too....

Did the transfer case and rear diff within the last 10K miles (18 mo. ago).

Gear switches when driving seems normal and smooth.

mikey00

Others (myself included) have fixed this problem by removing and cleaning the speed sensors, a fairly easy job. I believe that when the RX trans starts to go a lot of metallic fuzz gets created in the trans. The magnetic speed sensors are the first to pick up this metallic fuzz and provide incorrect readings causing this reverse issue. The speed sensor clean and swap definetly fixed my reverse problem but long term something is failing in the trans causing this metallic fuzz. My trans did eventually die. Here is a link with more info which also has a link to pics and directions:
https://www.clublexus.com/forums/rx-...-not-work.html

Lexmex

I forgot mikey00's experience on the speed sensors.

One thing that I do that I am not sure others do is leave the transmission dipstick open so that heat can escape. I've noticed some improvement with shifting since I started doing that in Mexico and even before I removed the windshield wiper fluid reservoir that is in front of the tranny cooler on the passenger side behind the bumper (just doesn't get enough cooling in my opinion).

deepbluesk

The symptoms described in that thread are exactly what I am experiencing. The first time it happened, it would not go into rev or neutral. I just cleaned the speed sensors, so we will see if that helps. They had a little of that transmission fuzz but not too much.

mikey00

Being that they are both the same, I also swapped their positions while I had them out for cleaning. The thought was that if one of them was going bad the symptoms may change.

deepbluesk

Do you happen to know which sensor deals with Rev/neutral ?

mikey00

No, I don't.
Something else to know is that if one of these sensors fail, you should get a check engine light with a OBDII code pointing to the sensor. There is also a procedure in the service manual for checking out the sensors once they are removed. Problem is the sensors don't go bad. They continue to work properly but the metallic fuzz on the sensor causes incorrect readings resulting in the reverse problem. That's just my theory.

deepbluesk

Just an update.... When I dropped the trany pan a couple weeks ago, I did find some metal slivers attached to all three of the magnets in the pan, which were not there at the last fluid/filter change. Since then, the reverse clunk/lockup only happened once and that was during the re-fill backing out of the garage. Since then everything has been working well. I may check the pan again in 6 months if things continue to operate smoothly. I still think I'm on the path to a transmission problem sometime down the road.