dalec1

My transmission overdrive light flashes on and off and will not go into overdrive, additionally, thespeedometer would bounce erratically. At that point I had 1 code, PO500-vehicle speed sensor, which I changed and corrected the speedometer problem, not the OD problem. I again pulled the codes and now I have PO500 vehicle speed sensor and PO720 output speed sensor. Any help would be appreciated.

b3player

I have the same problem. Does anyone know what to replace? And where is the location of the part? Thanks!

jawbone

Symptoms: speedometer, odometer, and cruise control not working, ck eng light on, O/D off light flashing.
tranny not shifting right/slipping out of gear
scan tool found code PO500

found my problem- Veh speed sensor (with speedometer gear) attached to tranny. located on top of differential (sensor installed at slight angle -directly below throttle body) Be aware there are two speed sensors on this V6 eng. ( I don't have the part numbers in front of me but one cost approx $100 (2 wires)and the other one cost approx $200 (3 wires)) I needed the $200 (3 wire)sensor.
What I found at first when I pulled the sensor was the sub assy gear teeth broken - this part can ordered from either Lexus or Toyota ( camry or es300 uses the same part # for the sub assy gear and also for the sensor)
(Note : the sensor does not come with the new gear teeth...gear is sold separate about $35.00)
I figured because the teeth were missing off the gear assy that the gear was no longer spinning which I figured was causing the sensor to fail. So I only replaced the gear assy at first..BUT...this didn't fix my problem. ( my symptoms reappeared after about 10 miles after replacing gear) Turn out My problem was the sensor itself was also bad. If you'll notice there are three screws on top of the sensor electrical connector. I removed the screws and pulled the connector off and found inside a broken magnetic pickup ring.washer broken. This magnetic pickup was my problem. I replaced the speed sensor , cleared the trouble code and my problem is fixed.

jchrisf

Good Info Jawbone Was your tranny not going into overdrive too?

jawbone

Yes my tranny was not going into overdrive, It was slipping out of gear causing my rmp gage to ramp up....not good.....I was able to drive (limp) home by pushing the the O/D button on the side of the shifter and that prevented the car from trying to go into overdrive or slipping.

b3player

Thanks for the replies. I got a sensor that was around 100 something, but it was not the one I needed.

Toyota sent me a picture of the other that is available. Is this the one that is needed?

If so, RockAuto has them a whole lot cheaper than Toyota / Lexus.


Thanks!


PICTURE OF SENSOR:
http://www.kennethgrice.com/Speed Sensor.pdf

jawbone

Hi bplayer,
I mentioned in my first post that you needed the 3wire $200 sensor.
Your Pdf looks like it but I can't say for sure. I did however go to Rockauto.com and searched and found the part number you need.
It is Part # SC149 (standard motor products Inc). You can see a perfectly clear photo of this sensor by doing a search by part number or you can search by vehicle. in your case follow this tree- part catolog,lexus,1994,es300,transmission-automatic,speed sensor....there it will show two sensors you need the sc149. good luck ...sorry I didn't include the part number in my first post...(Rockauto has great prices (i never heard of them), I paid approx $240 at toyota)

b3player

Hi, thanks jawbone!

I thought I found a good deal when I found the price on Rock Auto.

But I found a better price!

http://www.directauto.com/product-ex...T_Speed_Sensor

$39.95

I found the OEM number for the speed sensor on the drawing Toyota sent me and typed it in google. I found the speed sensor on directauto.com (link above) listed as a Toyota Camry speed sensor. (Uses same as lexus)

It is outrageous what the dealership and some parts houses markup their prices to.

So a great thing I have learned from all of this, is to ask Toyota for a drawing of the part if you don't have access to the part or book and search the net by OEM number!

Thanks again Jawbone!

b3player

Hi. Here is an update on the transmission problem. This second speed sensor did not fix the problem either. I went to a guy who specializes in electronics. I wanted to be sure before I tried to get a transmission. He found at that my ecu was bad. I got an used very cheap compared to over 900 bucks for a new one. The transmission now works like it is new. I hate I bought 2 speed sensors.

brownies8

I believe I may have the same problem. Where did you find a used ecu? How did you get it installed?

b3player

I got it from junk yard/salvage yard. Try eBay or you can search for parts at salvage shops near you
at car-part.com

Choose computer box engine for part name on car-part.com

Some say tested or rebuilt!

b3player

Oh I got it installed by a mechanic who works on import cars. Just check yellow pages. He had a garage at his house.

jjfncom

my transmission in the mornig takes 15 second to engage this when cold how long will it last? any solutions to it what can be the problem I have 100K on my Lexus 300ES 1994

melvinhine

overdrive light coming on 1994 gs300

dwinbolt

*My e-mail address is DWinbolt@yahoo.com. Please put something in the title so it doesn't go to spam. please contact me with questions.* Bought the car 5 years ago. I have been dealing with these circumstances since on my 1994 es. I work for a Toyota dealership and have access to repair information. nothing in the repair manual has been particularly helpful. all repair information directs a person to diagnose and repair for a speedo that is completely inop, and we all know that this is a fleeting issue. After I bought my es and experienced the warning lights, transmissions searching and rpm "flare: (transmission slipping), I got with my parts man to look for potential problems. Just to bore everyone, I will tell you all how the circuit works. The speed sensor is located on top of the transaxle housing towards the fire wall side of the transaxle. It It is not on the high point of the housing, but is actually down low. it is bolted to the transaxle by one bolt, and connected to the harness by a 3 pin connector. The speed sensor runs directly off the "final drive gear". I creates a weak voltage a/c signal. It is a curving up and down signal. The signal is sent TO the speedo head, where it is converted to a square wave a/c signal, that operates the speedo needle and and sends a signal to the ecm. Possible causes include, but are not limited to, the final drive gear, the speed sensor gear, the speedo head, the ecm, wiring and connectors in between the components.......now, back to the parts search. The first thing that my parts rep and I found was an old document, from Lexus showing an updated part number for the ecm, in connection with a TSB concerning this problem. I had the parts number in my billfold, but I can't find it. If you want the updated part number, call you local Lexus dealer, or if you can give me a day or 2 I will send you a snap shot of my computer. We found no part number changes for speed sensor or speedo head.
we all know the buying the ecm from Lexus would be cost prohibitive, if it is even available any more. the Toyota equivalent part is not the same. I spent years scouring local junk yards looking for the ecm with that part number. I found one, replaced my ecm, no check engine lights, life was good for about 6 months. then the symptoms returned. I know that computers can be left with old data and the require good battery voltage, so I have checked the battery AND have drained the the ecm capacitors. This is done simply by disconnecting the battery cables, yes both of the, then connect a jumper wire between the vehicle cable ends, NOT the battery terminals.Leave the jumper wire onf ro 30- 60 seconds. This will drain the capacitors and return the ecm to "full learning mode" This should be done whenever ANY efi component is replaced. Took my years to find this out, it is NOT published by Toyota/Lexus ANYWHERE. . Recently when diagnosing with my Toyota scan tool hooked up to the car, the pattern of symptoms seemed to be happening during engine warm up, just about the time that open loop/closed loop conversion occurs. The engine coolant temp sensor and throttle position sensor are wire in the same circuit. My conclusion was that if the coolant temp sensor was going open, or shorting out, that the TPS would send incorrect information to the computer and cause shift issues. OBD II Toyota/Lexus logic states that "an open circuit, or a short will set a code, and when it sees the malfunction 2x, the "check engine light" will come. Watching my scantool I never saw a the coolant temp figure waver. Subsequent drives show my symptoms can occur at any engine coolant temperature. I have never set a code for engine coolant temp too high or too low. My only codes are po500 and po720, both speed sensor codes. I will be shortly ordering a speed sensor and replacing the one in my car. the car has 213,000 miles on it and the speed sensor is probably the original on one. At this time I am flip-flopping on my decision as to whether to to buy the high priced part or buy a cheap one. I have ALWAYS put my repair money in Toyota/Lexus parts when possible. The Lexus part is nearly $400.00. Doesn't seem cost effective. Rock Auto ranges in price from about $15.00 to $160.00. NAPA IS ABOUT $150.00. I have discussed this with my (3) shop formen, we all conclude that the one moving/wearing part in the system is the speed sensor, and possibly the final drive gear When I replace the sensor, I will check for abnormal play in the speed sensor between the sensor housing and the speed gear, and I will also try to move the final drive gear around looking for abnormal play, and however unlikely I will look at all the gear teeth for wear, breakage....I will keep this car until it drops, so I want to fix it!.....My wife LOVES this car!.....Stay tuned for more information, and again feel free to e-mail me