Speedo and Flashing Overdrive Light issues

Knowing that things get forgotten rather quickly, I had better relate my experiences now! The first thing I noticed was that the speedo which is electrically driven on my 1993 Super Custom had brief periods of not working at all, both speed and odometer/trip meter. The brief periods of non-operation became longer periods and eventually became complete non-operation apart from just a few k's at the start of a journey when everything was cold. It was obvious that the build-up of temperature was a contributing factor.

I checked out various contributions on this and other forums and there seemed to be a consensus that the PCB on the back of the speedometer itself was the most likely cause of the problem. Contributors talked about burned tracks on the PCB and corroded tracks on the PCB, these being caused by leakage of the electrolytic capacitors. I removed the speedo several times and progressively dealt with overheated tracks and replacement of capacitors. No corrosion was noted. On my second last time to refit the instrument cluster, I attached a test cable to the sensor input to the speedo. To this I connected an analogue multimeter. On starting the engine, I noted a voltage of approximately 10 volts indicated. On allowing the vehicle to move forward slowly, I noted the voltage went to 0 volts. Rolling further forward, it was back to 10 volts and further forward still, 0 volts again.

On the road, the multimeter averaged the voltage at 5 volts simply because the needle was unable to move quickly enough between 0 and 10 volts! Alas, even with multiple removal of the instrument cluster, cleaning and soldering tracks (and even bridging of suspect parts of a track with wire) along with replacement of capacitors - DID NOTHING AT ALL to solve my problem. I have no doubt that what I have done will help to make the speedo more reliable for a few years to come.

Back to the readings on the multimeter. During the time speedometer was working properly, (usually for no more than about 5km) the multimeter showed approximately 5 volts (unless I was waiting at traffic lights or a pedestrian crossing - where it might have been showing either 0 volts or 10 volts). When the speedo stopped, the voltage changed to approximately 7 volts and it no longer made any difference whether the vehicle was moving or not. There was no longer any fluctuation in the voltage shown - it was just 7 volts all the time.

Having tried everything else, I had to blame the Vehicle Speed Sensor (speedometer sensor) which is fitted to the rear end of the gearbox extension. I made no attempt to remove it from the vehicle - I just ordered a new one! I checked the internet using the original TOYOTA part number and discovered there was at least one part supplier that was equipped to import original parts from Japan into Australia. The name of the company is AMAYAMA. I checked the part within their website and the price came up as $121.30. I clearly anticipated there would be charges additional to that price to cover freight and the like. I phoned my local TOYOTA dealer parts department and was told by a guy that I know that the part was available in Australia and that the retail price was $414.00. On hearing that, I went back to the internet and initiated a parts inquiry for the sensor. The company got back to me within a couple of days and the price was given as $151.36 including handling and freight and Australian GST. It took a couple of weeks for the part to arrive and it was dead easy to fit. The problem is now history - no more speedo issues and no more flashing overdrive light!

Oh yes, the flashing overdrive off light. Even though the speedo was not working most of the time, I continued to drive the vehicle and try not to go faster than other cars on the road! Usually within 10km or 30 minutes of the speedo stopping working, the overdrive light would begin flashing. I understand that the flashing light indicates a problem with the gearbox or the information it is getting from the sensor via the instrument cluster. I noted that changes-up sometimes seemed to be delayed - but they were manageable. The performance of the vehicle was not compromised to any real degree. The replacement of the Vehicle Speed Sensor has completely eliminated that problem as well as dealing with the speedo issue. One website stated clearly that if there was a problem with the speedo AND the transmission, that the problem was clearly the speed sensor. But then, so many people have aired what they did to fix problems involving the speedo and the overdrive light. It seems I had to do it my way!

I have presented the above, not as a fix for the problems of others necessarily, but what I did and my findings in the process of fixing the problem.

Thanks so much for sharing...I have smae problem exactly, except trany fluid is coming up the cable...which I understand is an internal o ring in the gear driving speedo cable? So should be an easy fix. Thanks again