How the Combination Relay Powers the Fuel PumpWith the ignition switch in the "Start" or "Run" position, current flows through terminal 86c of the combination relay, the coil of the relay, and terminal 85 of the relay, to terminal 28 of the electronic control unit (ecu). The control relay contacts close in the combination relay. Current then flows from the battery, through terminal 88z and the closed contacts of the combination relay via terminals 88b and 88e to the fuel injectors. Because the engine is not yet running, there is no air flow and the fuel pump switch, located in the air flow meter, remains open.With the ignition switch in the "Start" position, current also flows through terminal 86a of the combination relay and follows three paths: - the coil of the combination relay to terminal 85 of the relay to terminal 28 of the ecu;
- terminal 86 of the relay to terminal 4 of the ecu;
- terminal 86 of the relay to the cold start valve and the thermo-time switch.
Path 1 causes the contacts of the fuel pump relay to close. Current then flows from the positive side of the battery, through the fuel injection in-line fuse, to terminal 88z of the combination relay, through the contacts of the relay, to terminal 88d of the relay, to the fuel pump. Path 2 powers a start signal through terminal 4 of the electronic control unit. The ecu is then allowed to ground the fuel injectors (through a ground wire attached to the right hand side of the intake manifold), allowing the injectors to operate. Path 3 powers the cold start valve through the thermo-time switch (if the coolant temperature is below 95°F / 35°C). The thermo-time switch remains closed and the cold start valve operates, until: - the coolant temperature goes above 95°F / 35°C; or
- the current flow through the heater in the thermo-time switch generates enough heat to open the switch.
With the ignition switch in the "Run" position, current no longer flows from terminal 86a to operate the fuel pump relay. Once the engine is running, air is flowing through the air filter and the air flow meter to the intake manifold. This causes the contacts (terminals 36 and 39) of the fuel pump switch, in the air flow meter, to close. Current then flows from the positive side of the battery to terminal 88z of the combination relay, through the contacts of the relay, to terminal 88a of the relay, to the now-closed contacts of the fuel pump switch in the air flow meter, to terminal 86b of the relay, to the relay coil, closing the contacts between terminal 88y and 88d of the relay, allowing current to flow to the fuel pump. The contacts remain closed and the fuel pump operates until the engine stops or stalls, at which time the fuel pump switch in the air flow meter opens, stopping the fuel pump. Fiat Spider Combination Relay 
Terminal
| Connection | Wire Color (s) |
| 85 | Injection ECU (terminal 28) | White | | 86 | Injection ECU (terminal 4)
Cold-Start Valve (terminal 47)
Thermo-time Switch (terminal 45) | White | | 86a | Ignition switch "start" output (terminal 50) | Red/Black | | 86b | Injection ECU (terminal 20)
Airflow Meter (terminal 36) | White | | 86c | Ignition switch "run" output (terminal 15/54) via fuse "A" | Pink/Black | | 88a | Injection ECU (terminal 10)
Airflow Meter (terminal 39) | White | | 88b | Injector 3 (terminal 41)
Injector 4 (terminal 40) | White | | 88c | Auxiliary Air Valve (terminal 48) | White | | 88d | Fuel Pump | Green/Black | | 88e | Injector 1 (terminal 37)
Injector 2 (terminal 38)
Injection ECU (terminal 29) | White | | 88z | Battery 12V+ | Brown | | 88y | Ignition switch (terminal 30) via fuel injection in-line fuse | Brown/White | Fiat 2000 Fuel Injection Electrical Schematic 
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