Ok.
On the V1.0 hardware another PMIC is used, there is no dedicated regulator for the SD card communication voltage. GPIO1_IO04 controls a switch between 1.8V and 3.3V.
For me an overlay which sets the pin GPIO1_IO04 to the function GPIO1_IO04 allows me to later control the voltage. (with gpioset 0 4=1 I do get 1.8V).
- Are you sure you recompiled and deployed the device tree overlay?
- What is the output of
devmem2 0x30330038
Max
P.S. I recommend to move to V1.1 hardware as soon as possible. There have been a lot of incompatible changes, among others also additional pullups on the SD interface.