29.2.2.3 SDA and SCL Pins
Selection of any I2C mode with the SSPEN bit set forces the SCL and SDA pins to be open-drain. These pins must be configured as inputs by setting the appropriate TRIS bits.
Important: Any device pin can be
selected for SDA and SCL functions with the PPS peripheral. These functions are
bidirectional. The SDA input is selected with the SSPxDATPPS registers. The SCL input is
selected with the SSPxCLKPPS registers. Outputs are selected with the RxyPPS registers. It
is the user’s responsibility to make the selections so that both the input and the output
for each function is on the same pin.