G50: Hard Shifting Due to Bad Temp. Sensor, A Solution.

[sdkhalsa]

I wrote last week about harsh shifting which I thought was due to a bad transmission temp. sensor.After getting out my VOM, I found this to be the case, with all sorts of changes in values at higher temperature. Rather than spending a lot of time and money to dig out the old sensor, I soldered an adjustable resistor(trim pot) in the wiring just below the TCU cutting the connections with the transmission sensor. Normally, the voltage at TCU Pin #33 runs from 1.5V to .5V(cold to hot). I set the value at .75V(about 850 ohms). This has totally taken care of the shifting problem while at the same time maintained good performance when the transmission is cold. One special note here: I live in Arizona, so the temperature in the morning is almost 80 deg. to begin with. If you lived in a colder climate, this solution might require a different approach. My thought is that in a different season or different climate you might want to adjust the resistor to a different value.

[elwesso]

Very good information... Thanks!

[Q45tech]

Members can trim [not totally substitute] many sensors to correct minor aging problems, AS LONG AS YOU COMPLETELY UNDERSTAND WHAT THE SIDE EFFECTS MIGHT BE.KS, COOLANT, MAF, transmission, Injectors harder and more expensive, fuel pressure harder and more expensive.

Back in Motronic days BMW European car had dip switches to compensate ecu for lower octane gasoline and summer vs winter as the cars moved from country to country.