Sensor Chart - Lowrance X-28 Installation And Operation Instructions Manual

(Note: Do not use these sensors in any other combination.)
ST-TBK = 1 speed sensor and 1 temperature display
ST-T BK + TS-2BK = 2 temp sensors and one speed sensor
ST-TBK + TS-2BK + TS-3BK = 3 temp sensors and one speed sensor
TS-1BK = 1 temperature sensor
TS-12BK = 2 temperature sensors
TS-1BK + TS-2BK = 2 temperature sensors
TS-12BK + TS-3BK = 3 temperature sensors
TS-1BK + TS-2BK +TS-3BK = 3 temperature sensors
Here's some sample wiring diagrams:
Two Temperature Sensors
(Water and T-2)

Sensor Chart

or
or
X-38 or X-48 POWER CABLE
TS-12 BK
14