This tells you what cables to connect for what procedure:
https://www.multiecuscan.net/SupportedVehiclesList.aspx
Fiat
500
1.2 8V Magneti Marelli IAW 5SF8 CF5/EOBD Injection (8V) |INFO|DTC|DTC EX|PRM|ACT|ADJ| ELM
Magneti Marelli IAW 5SF8/SDU CF5/EOBD Injection (1.2 8V LPG, 1.4 8V LPG) |INFO|DTC|DTC EX|PRM|ACT|ADJ| ELM
Magneti Marelli IAW 5SF9 CF5/EOBD Injection (1.2 8V, 1.4 8V) |INFO|DTC|DTC EX|PRM|ACT|ADJ| ELM
Magneti Marelli IAW 9GF CF6/EOBD Injection (1.2 8V LPG) |INFO|DTC|DTC EX|PRM|ACT|ADJ| ELM
Magneti Marelli IAW 9GF CF6/EOBD Injection (1.2, 1.4) |INFO|DTC|DTC EX|PRM|ACT|ADJ| ELM
Marelli SELESPEED CFC328 Automatic Gearbox |INFO|DTC|DTC EX|PRM|ACT|ADJ| ELM
Marelli SELESPEED CFC328 CF6 Automatic Gearbox |INFO|DTC|DTC EX|PRM|ACT|ADJ| ELM
Marelli SELESPEED CFC328F Automatic Gearbox |INFO|DTC|DTC EX|PRM|ACT|ADJ| ELM
Bosch ABS 8 ESP |INFO|DTC|DTC EX|PRM|ACT|ADJ| ELM
Bosch ABS 9 ESP |INFO|DTC|DTC EX|PRM|ACT|ADJ| ELM
Continental Airbag (Ep - PROXI) |INFO|DTC|DTC EX|PRM|ACT| ELM A3
Continental Airbag MY12 |INFO|DTC|DTC EX|PRM| ELM A3
Siemens Airbag MY06 (Ep - PROXI) |INFO|DTC|DTC EX|PRM|ACT| ELM A3
TRW Airbag MY12 |INFO|DTC|DTC EX|PRM| ELM A3
Delphi Electric Steering |INFO|DTC|DTC EX|PRM|ADJ| ELM
Delphi Electric Steering MY12 |INFO|DTC|DTC EX|PRM|ADJ| ELM
Service Interval Reset |INFO|ADJ| ELM A3
Service Interval Reset MY12 |INFO|DTC|PRM|ADJ| ELM A3
Service Interval Reset MY13 |INFO|ADJ| ELM A3
Service Interval Reset TFT |INFO|ADJ| ELM A3
Convergence Lauberhorn (Blue&Me) |INFO|DTC|PRM| ELM A3
Convergence Marelli/Microsoft (Blue&Me) |INFO|DTC| ELM A3
Convergence Marelli/Microsoft C3 (Blue&Me Nav) |INFO|DTC| ELM A3
Instrument Panel Marelli |INFO|DTC|DTC EX|PRM|ACT|ADJ| ELM A3
Instrument Panel Marelli MY12 |INFO|DTC|DTC EX|PRM|ACT|ADJ| ELM A3
Instrument Panel Marelli MY13 |INFO|DTC|DTC EX|PRM|ACT|ADJ| ELM A3
Instrument Panel Marelli TFT |INFO|DTC|DTC EX|PRM|ACT|ADJ| ELM A3
Uconnect Radio/Nav 5" |INFO|DTC|PRM|ADJ| ELM A3
Uconnect Radio/Nav 7" |INFO|DTC|PRM|ADJ| ELM A3
Body Computer Delphi (312) |INFO|DTC|DTC EX|PRM|ACT|ADJ| ELM A3
Body Computer Delphi (312) MY12 |INFO|DTC|DTC EX|PRM|ACT|ADJ| ELM A3
CAN Info |INFO| ELM A3
CAN Setup / PROXI Alignment Procedure |INFO|ADJ| ELM A3
CAN Setup / PROXI Alignment Procedure (2014+) |INFO|ADJ| ELM A3
Denso climate control (Single zone) |INFO|DTC|DTC EX|PRM|ACT|ADJ| ELM A3
Denso climate control (Single zone/PTC) |INFO|DTC|DTC EX|PRM|ACT|ADJ| ELM A3
Litronic XENON headlamp (left) |INFO|DTC|PRM|ACT|ADJ| KLELM A3 P12
Litronic XENON headlamp (right) |INFO|DTC|PRM|ACT| KLELM A3 P12
Parking control Valeo |INFO|DTC|DTC EX|PRM|ADJ| ELM A3
Tire Pressure Control (TPMS) |INFO|DTC|DTC EX|PRM|ACT|ADJ| ELM A3
KL - KKL/VagCom/OBDKey interface
ELM - ELM 327 v1.3+/OBDLink/OBDKey interface
A1 - ADAPTER CABLE 1 (green)
A2 - ADAPTER CABLE 2 (red)
A3 - ADAPTER CABLE 3 (yellow)
A4 - ADAPTER CABLE 4 (purple)
A5 - ADAPTER CABLE 5 (blue)
A6 - ADAPTER CABLE 6 (gray)
3-Pin - 3-PIN ADAPTER CABLE
P1 - Pin 1 (for interfaces with pin switch)
P3 - Pin 3 (for interfaces with pin switch)
P9 - Pin 9 (for interfaces with pin switch)
P12 - Pin 12 (for interfaces with pin switch)
P13 - Pin 13 (for interfaces with pin switch)
looks like you only need the OBD2 cable for the engine.