I have these codes as well as shift range inhibited on my 03 duramax. Please help I am way out of warranty.
P0700
Transmission Control
Module (TCM) Requested
MIL Illumination
ECM, TCM
DTC P0700 in Automatic
Transmission - Allison
or
DTC P0700 in Engine Controls -
6.6L (LLY)

P0708
Transmission Range (TR)
Switch Circuit High Voltage TCM DTC P0708 in Automatic

Check the wiring harness at the passenger side of the alternator. There is a sharp edge that wears into the harness which can cause a short.:cool:

NSBU switch is probably bad.

Is it hard to replace?