Automagic

Its a sensor issue. The automatic sc's have both a Vehicle Speed Sensor (VSS) and a Transmission Speed Sensor (TSS). That issue with first gear not shifting until you completely lift off the gas and then get back on it is a TSS issue. It also usually causes the O/D Light to flash on and off as well as occasionally when accelerating, say from a stoplight, the car really struggles to get going and the car revs all the way out.

This is happening to my buddy's sc and I just got the new TSS in so within the week im going to be replacing his. I have no idea where the sensor is located. Idk if im going to have to drop the trans or if its easy access like if its on the side of the trans but Im going to give it a shot.

tzxlyd

Were you able to find out where the VSS is located? I am having a similar issue. I did see some YouTube videos that showed this to be a simple fix. No need to drop the transmission. Seems you can get to the VSS either from under the car by removing front tire or from above by removing the intake box. If you have not located it, I plan on trying to get to mine on tomorrow. Once I have located it I will post that information if it has not already been left by someone. Like you I have been having a problem with my speedometer dropping to 0 and my odometer no longer counting as well as my check engine light. Unfortunately, I am now having an additional problem of having to replace my alternator. I already have the VSS and I am awaiting my alternator. Once I have everything I will do the repairs.

tzxlyd

As a follow-up to my earlier post I decided to search for the VSS on my 1997 SC300 after seeing no further information on this thread today. I thought to make it easier I should call the local Lexus parts dept. for assistance. I was told that there is a VSS connected to each of the ABS. While this did not really make sense to me I decided to begin with the front LH of my car. I jacked it up to get under it but I could not find any sensor. I did see something covered by a rubber cap so I decided to remove the cap and I saw a screw with 2 bolts on it. Out of curiosity I removed both nuts and found a black piece of plastic with remains of something that had clearly been broken off at some earlier point. This piece of plastic was not far from the transmission fluid line leading into the transmission. I decided to take a look from above down the transmission fluid line and about 6 inches below the dip stick I saw a blue connector just dangling with nothing attached to it. Clearly, this was weird because it was too far above the transmission to be the VSS so as I studied it more closely I noticed it had two female receptors. I suspected that there was a missing harness that had some how been either removed and left off of the vehicle during a period when my car was serviced. I knew that the VSS had two male pins and was slotted in the exact shape as this dangling blue connector. So I plugged it in and it fit perfectly. This confirmed in my mind that somehow the harness that leads to my VSS had been possibly yank off the car because it was perhaps dangling because it had not been placed back into the connector by a mechanic. I called the local Lexus parts dept. back to get a harness and then explained my discovery. I asked if they could see on the parts diagram exactly where the VSS could feed into the transmission? This led to a lot of head scratching by the parts dept. and I was sent a copy of the diagram because there is no sign of where the VSS feeds into the transmission. The parts dept. decided to consult with some of the mechanics and none of them could figure it out either. I was told to contact the Service Mgr. because the mechanics said they need to see the vehicle to determine exactly where the VSS is housed on the transmission. I contacted the Service Mgr., then left a message but I have not heard back from him yet. Once I find out more about this I will post that information. The absence of the harness and a VSS would seem to explain why my speedometer drops to 0 after driving a few miles and the odometer stops counting -- or at least I hope so. Now I wonder how the speedometer has worked at all without the VSS -- could there actually be 4 speed sensors and my speedometer and odometer are working from the speed of the wheels in the absence of the transmission VSS? More to follow on this mystery.

Automagic

Well i have no idea about any blue connections but I can tell you where the TSS and the VSS are at. Both of these connections will be found on the drivers side of the transmission directly above where the crossbeam is supporting the trans.

tzxlyd

Yes, that is correct -- just jack the car up on the driver side and near the back of the driver door (on the transmission) you will see the area where the VSS is located. I found the VSS on the transmission and I found out about the dangling blue connector. The VSS is where you said and I am attaching the photos that I took of it the next day after my last post (the red rag is the opening where the VSS goes into the transmission and the connector you see plugs into the opposite end -- there is only one bolt so just unscrew the bolt before trying to remove the connector it is easier that way). I ran into another problem with the new VSS -- it would not fit into the transmission. The new part # 889413-08020 that superseded the old part # 89413-24010 will not fit into the transmission. I spent most of the afternoon of 3/11/15 at the local Lexus dealership's parts dept. trying to figure out the problem because I could not understand why the new part will not fit. The parts dept. spent hours trying to find out the problem and ultimately I ended up speaking with the service manager. The service manager got a caliper and noticed a slight difference in the size. However, he stated that he believes there is rust inside of the area where the VSS reads the rotation and suggested that I get a small pipe brush to clean out the area. I have not done that but I have a small round sharpening file that I will probably use to do the same and it will probably help to enlarge the opening enough to get the VSS into the opening. The other issue I was have with the blue dangling connector was resolved because luckily there was a 1997 SC400 being serviced so we were able to go look at it and saw where it was connected on the SC400. I am certain this was the reason for my check engine light problem because it would have been causing oxygen failure problems that would have been reported as O2 sensor problems. I did not get a chance to work on the VSS today because I installed a new alternator and decided to do some much need cleaning up of the engine bay area and the area under the transmission. I will be doing a complete tune-up probably later this year and replace all of the O2 sensors so I thought it would be a good time to clean those areas before my next big repair job. I am attaching the photos of the location of the VSS on the transmission for anyone who has to tackle that minor job in the future.

victorhugo

Ihave a 92 sc300 n my speedometer wont move until 35 mph can this b a transmission sensor or something?

tzxlyd

Victorhugo,
What about your odometer? Is the odometer working (counting mileage) when you speedometer is not working? If both are malfunctioning at the same time, then the problem is most likely your transmission VSS.

RayRay496

Yes im trying to test both speed sensors on my 97 lexus sc300 A/T, cause of a issue of my tranny does not shift out of 1st gear. Anybody have the location of both and maybe some insight.

tzxlyd

RayRay496,
If you take a look at my 3-13-15 post you will see exactly where to find the VSS.