So me thinks I have everything hooked up right , car drives and shifts great except when i push the overdrive button to go into 4 gear it won't stay in 4 it switches from 3to4 to3 to4 to3 to4 till I push the od button back in and then in 3rd at about 60mph I'm running a little above 3 grand.no good for highway can anyone help me. could this be a bad sensor, I did remove the speedo sensor to use my cable speedo. or maybe if I unhook the wires to my od button will it shift to 4th on its own.unfortunately it is crappy snowy here have not been able to try things. any autos out there with knowledge please help.
over drive on auto tranny
- Thread starter odomd
- Start date
The auto tranny needs the electronic speed sensor to know what gear to go in.......................
The OD button is just a 12v switch to the ECU, to tell the ECU that at 40+mph, its ok to put the transmission in 4th gear. 0v, OD off, 12v, OD on.
It probably shifts from 1st to 3rd in the matter of hitting 20mph also, right? Thats a default failsafe when theres a sensor failure. The ecu reads that your in 3rd gear, at whatever RPM, so on the shift tables, it tells the ECU ok to shift to 4th, but the ECU is also reading zero mph, so goes back to 3rd because it didnt meet the requirements of 4th gear on the MPH table. Endless loop.
There is no fix, except hookup the speed sensor.
The OD button is just a 12v switch to the ECU, to tell the ECU that at 40+mph, its ok to put the transmission in 4th gear. 0v, OD off, 12v, OD on.
It probably shifts from 1st to 3rd in the matter of hitting 20mph also, right? Thats a default failsafe when theres a sensor failure. The ecu reads that your in 3rd gear, at whatever RPM, so on the shift tables, it tells the ECU ok to shift to 4th, but the ECU is also reading zero mph, so goes back to 3rd because it didnt meet the requirements of 4th gear on the MPH table. Endless loop.
There is no fix, except hookup the speed sensor.
I am using the 1j auto. It does shift form 1st to 2nd to 3rd normally and when I punchit it, it does'nt shift till about 5,000 rpm for each gear. Is what you are saying that I either get correct speed with my cable or no speed but 4th gear by putting the sensor back? any way to trick it?
Theres no trick. Its an electronically controlled transmission that needs speed input to the ECU to shift correctly. Do some searching, im not a MKIII expert on how to make your cable speedo work with the a70 electronic setup.
yes, just swap in an aftermarket electronic speedo, or a mark 4 one.
im assuming on your engine set it was from either a TT limited or from a Soarer?
your easiest bet would be to just swap in an electronic speedo, eliminates the somewhat unrealiable cable.
im assuming on your engine set it was from either a TT limited or from a Soarer?
your easiest bet would be to just swap in an electronic speedo, eliminates the somewhat unrealiable cable.
i wouldnt, the higher miles of it and the slight differences might play hell with a soarer ecu, seriously get a spare cluster and see about a electronic speedo, less work then swapping out trannies.
I have a Aristo 2JZ/auto (swap yet finished)... and am going to use the Apexi speed/rev meter (~$160) for a speedo, as well as to remove speed cut, etc. I am positive it has a speed signal output, which may help in your case.
The TT tranny is electronic, so I don't have any use of/for the 7M/MKIII speedo cable.
The TT tranny is electronic, so I don't have any use of/for the 7M/MKIII speedo cable.
My limited understanding is the ECT needs 2 x speed signals that it compares and if either aren't present it defaults to limp mode.