1998 Toyota Picnic, 7seater, automatic minivan. This is a USA product for export. I live in Germany and enjoy your show on AFN. Problem; Tach, speedometer & OD indicator whacky. The Trany shifts up almost normal but when I give it a stomp to pass it will shift down at least 1 gear lower than it should causing high revs. Each time the car is started the Tach may show a different RPM and remain so for the day, never changing. The Speedo registers some dumb speed any where from 20-80KmH (also at a stop) and usually remains there for the day. I don’t want to kill the trany so I don’t try a quick acceleration any more. What is wrong with my otherwise perfect car with 200,000+ KM.
The transmission issue sounds normal. When you stomp the gas, the transmission should drop out of OD, and drop a gear, seemingly dropping 2 gears. This is normal, and will not damage the transmission or engine. The ECM will not allow the engine to over-rev.
The other problem is probably a bad connection on the gauge cluster. This will need to be removed and the electrical connections cleaned and coated with a dieletric grease. This type of grease will prevent moisture from causing electrical signal problems and will not conduct electricity. I ad a similar problem with my 2000 Ford Explorer, and doing this fixed my gauges.
BTW, the gauge luster is completely electric. There are no speedo cables or anything else like that to contend with, just electrical connectors. This is just an interface for the ECM to tell you what’s going on with the van and engine.
I tried that at both ends. At the gauge cluster and at the Trany output end to no avail.
Not sure how this car is configured, but most modern cars have a speed sensor that monitors the rotational speed of the transmission input shaft. (and maybe one at the output too) If this is failing, it’s easy to see how it could affect the tachometer and speedometer–this is probably where the information for both comes from. If the transmission is electronically controlled, it may be confusing the transmission computer too, causing it to drop down too many gears.