Getting the final feature of my project working on my new T4.0 involves hooking up the Teensy SD adapter to the breadboard. The LCD screen works fine until I connect the SCLK of the SD board. These are the only two SPI peripherals on the board. I don't even have to connect MOSI/MISO/CS. I'm not really a hardware guy, I'm a software guy, but this points to the clock signal somehow getting screwed up by this connection.

At first, I thought it may have been introducing too much capacitance from the extra breadboard rail and it was causing the clock signal to not be clean enough. So I took the SD adapter off the BB and hooked it up directly to the pins with jumper wires. The LCD still doesn't work when it's connected.

The LCD I'm using is the ILI9341 that's available on this site.

Unfortunately, I don't own a scope to help me diagnose this. Any pointers for a hardware newbie?