4eat Transmission + P0734 code

[Marcelh]

I need some help with my 2005 Baja Turbo with 4EAT Trans

when driving In D mode I get a P0734 code Gear 4 Incorrect Ratio and CEL and Trans overheat lights come on and Cruise flashes

it no longer will shift higher than 3rd gear when this happens, if you clear codes out everything works again, Also if you use

manual mode and shift manually there are no issues, also depends on how you drive as Turbo kicks in at 3,000 rpm and before

you know it it shifts so quick and so forth so I think the car is getting confused, car has 140k on it fluid and filter where just

changed awhile back and level is fine, also if you do full throttle run where shift is higher in RPM's again no issues, no leaks etc.

Any help is appreciated.

Thanks

[silverton]

This is titled P0736, but diagnostics for P0734 is the same.

You will need a scan tool to perform the diagnostics, a basic one with live data display should be able to display these things.

If the value of the accelerator position live data does not increase/decrease smoothly, replace the accelerator position sensor.

If that checks out, lift all four wheels off the ground SAFELY, start the vehicle and drive it in D.  If the speed shown on the live data does not correspond with the instrument cluster speedometer replace the front speed sensor. You can likely do this with a road test, just have someone with you watching the live data and the speedometer.

If that checks out, idle the engine and verify that the speed sensor revolution live data should closely correspond with the instrument cluster tachometer. If yes there is a fault in the TCM, TCM connector/wiring, or the transmission assembly itself. If no, it's the turbine speed sensor circuit.