Toyomoho, I just read a reply you posted on an older topic with a link to this discussion here: https://www.cargurus.com/Cars/Discus...17828_ds549663
An electrical engineer named James figured out that if your speedometer AND your odometer stop working, (Odometer is blank) and your transmission shifts badly, then this points to the resonator on the speedometer circuit board being degraded from the heat and no longer allowing oscillation. Evidently, the VSS generates a signal which goes to the combination meter (speedometer and odometer) where it get converted to a 4 pulse square wave that is sent to the pcm. This part degrades over the years from the high heat inside the car in the summers. It can sometimes be intermittent when it is hot and start working once the inside of the car cools a little. He said if it was the VSS being bad and not sending a signal to the Speedometer, then the odometer would still be on, just not counting up. So, I located and ordered the little part ZTT-4.00mg. (3 pin Ceramic resonator) You can get them from digikey for under $1 (plus shipping) or they are sold on ebay too. If someone has this problem but can't de-solder/solder parts on a circuit board, then replacing the speedometer would fix it as well. I didn't want to get a used speedo from a junkyard or ebay because it will have the same original part that has either already failed, or will fail in the future depending upon how much heat it was exposed to over its lifetime. James pointed out that this only works if your car's speedometer stops working AND the odometer is blank and your transmission shifts badly. He said that a bad VSS would not make the odometer go blank but could cause the other two symptoms. I also had the CEL light up and got OBDII code P0500 which indicates an issue with the VSS which others reported having too. Everyone that did this fix reported back that it worked perfectly. I already ordered the new Toyota VSS which I will keep as a spare if this cheap and easy fix works for me as well. I am very glad you posted that link in that other thread or I never would have known this. I suggest that anyone who has these symptoms in an older Toyota read the entire thread on the link. Thanks again.

Bill

 

I remember this post. Amazing the resourcefulness of members to dig down to the root cause of a problem and find a solution.

 

Just to update, my resonator arrived yesterday and I pulled the instrument panel and removed the speedometer and unsoldered the old resonator. Some people that posted on the forum posts mentioned in my earlier post said they soldered the new resonator on the back side of the circuit board because the could not reach inside. I used a pair of hemostats and was able to solder it into its original location. It was not easy but with some patience I was able to do it. If the photo shows up here you can see the little blue resonator inside the speedometer. You can't take it apart further to allow easier access to it without messing up the speedometer calibration/action. I forgot to take photos while doing this so I took a screen shot from a youtube video where a guy make the same repair to his lexus speedometer using the same resonator. I put everything back together and, my speedometer now works and my odometer is on and counting up and my transmission shifts normally. I am very grateful that Toyomoho made that post about this cheap, simple but effective repair. According to what I read over there, many dealers do not even know about this and replace the VSS and then when that does not fix it, the entire speedometer costing hundreds of dollars. I am keeping my VSS on the shelf just in case I need it someday. I am very thankful for all the information shared on this forum.

Bill