03 S80 Gear Select Malfunction post trans rebuild

[Mark27]

Hello All,
I had to rebuild my 4t65e for the second time. I finally finished assembling the transmission and completed the installation. When I tried to start the car, it would not start and all I heard was a click and the “check engine” blinked approximately 8 times. I further noticed the gear select knob indicator was in “R”everse instead of “P”ark, the actual gear it was in. The display on the instrument cluster also indicated the car was in reverse. I then tried to put the gear select in “N”eutral and it indicated the car was in “D”rive. I should mention the display briefly read 1 when I placed the gear select in geartronic mode but it displayed “D” again when I shifted out of it and returned. After shifting the knob through the different gears a few times, the gear select will only indicate “D” when in geartronic mode.

I then proceeded to remove the gear select cable from the transmission since I had to replace it (used part from online salvage site) when the original broke during the removal process. I manually placed the transmission select to the park position (last position in the direction of the fire wall). Both the gear select and instrument cluster again indicated the car was in reverse. In summary, regardless of what gear is chosen, the gear select indicator indicates the transmission is either in “R” when the gear is really in park or “D” in all other gears including geartronic. Any thoughts on why this is occurring or what could I have done incorrectly during the rebuild process. In addition, any trobleshooting suggestions?
Also the safety feature that prevents key removal when the car is not in park functions as expected. The key can be removed when the gear select is placed in park although it indicates it’s in reverse.

Thanks for any help and best regards

[MyS40T4]

It sounds like a mismatch between the gear selector in the gearbox and the position of the gear selector in the car.

This could be a cable issue or the more scary option is an internal selector switch issue. Given you changed the gearshift cable, the old adage "check the last thing you did" applies I think!

To test the gear shift cable, set the gear shift in the car to neutral and disconnect the gear shift cable at the gearbox end, and if you can, experiment with locating neutral manually with the selector lever on the gearbox. It should be the second position from one end [i.e. P(end)>R(1)>N(2)]. I think this will be verified on the dashboard gear selection display. I'd do all this with the cars front wheels off the ground so that when you try to start it, it doesn't go anywhere (it shouldn't, but just in case). Once you've figured where neutral is, try and start it and see what happens...If this all works then it's something with the cable...

A gearbox gear selector switch issue will be harder to fix as you might have to disassemble the gearbox...

Hopefully this helps??

Cheers,

Chris

[Mark27]

Thanks Chris, unfortunately it's a gearbox issue. The internal mode switch (range switch on shift detent plate) is out of correct position. I will have to remove and dismantle the gearbox again,which is no fun on the east coast during the mid summer