Test B: EEC-V Power Relay

NOTE: After each service or repair procedure has been completed, reconnect all components. Clear DTCs and repeat QUICK TEST procedures to ensure all EEC-V systems are working properly and DTCs are no longer present.

This system test is only intended to diagnose the following components and circuits:

Vehicle Wiring Harness Circuits: Vehicle Power (VPWR), IGN START/RUN, Battery Positive Voltage (B+) & Power Relay Ground
Power Relay

1) Check VPWR Circuit Resistance

Turn ignition switch to OFF position. Disconnect Idle Air Control (IAC) solenoid harness connector. Disconnect scan tool. Disconnect power relay. Using a DVOM, measure resistance of VPWR circuit between IAC valve harness connector and power relay harness connector. See Fig 1 or Fig 2 . If resistance is less than 5 ohms, reconnect IAC valve and go to next step. If resistance is 5 ohms or more, repair open in VPWR circuit between power relay and IAC valve.

Fig 1: Identifying Power Relay Circuits (Except Tribute)
Courtesy of FORD MOTOR CO.

Fig 2: Identifying Power Relay Circuits (Tribute)
Courtesy of FORD MOTOR CO.

2) Check Voltage To Power Relay

Ensure ignition switch is turned to OFF position and power relay is disconnected. Using a DVOM, measure voltage between negative battery terminal and B+ terminal at power relay harness connector. Note voltage measurement. Turn ignition switch to ON position. Using a DVOM, measure voltage between negative battery terminal and IGN START/RUN terminal at power relay harness connector. If either voltage measurement is 10.5 volts or less, repair open circuit. If both voltage measurements are more than 10.5 volts, go to next step.

3) Check Ground Circuit To Power Relay

Using a DVOM, measure voltage between ground terminal and B+ terminal at power relay harness connector. If voltage is more than 10.5 volts, replace power relay. If voltage is 10.5 volts or less, repair open in ground circuit.
NOTE: A break in step numbering sequence occurs at this point. Procedure skips from step 3) to step 5). No test procedures have been omitted.

NOTE: VPWR fuse No. 111 (15-amp), feeds HO2S heater, SSR (air pump relay) and WOT A/C cutoff relay circuits. VPWR fuse No. 112 (10-amp), feeds Coil On Plug (COP) and ignition transformer capacitor circuits. For fuse locations, see WIRING DIAGRAMS article.

5) Check Power To VPWR Circuit Fuse

Remove and inspect other VPWR circuit fuse that goes to components supplied by power relay No. 2. Replace fuse as necessary. Turn ignition switch to ON position. Using a DVOM, measure voltage between negative battery terminal and both VPWR circuit fuse harness connectors from power relay No. 2. If both voltage measurements are more than 10.5 volts, repair open between fuse and component. If both voltages are 10.5 volts or less, turn ignition switch to OFF position and go to next step. If only one measurement is more than 10.5 volts, repair open in VPWR circuit between fuse and splice.

6) Check VPWR Circuit Continuity Between Fuse & Power Relay No. 2

Disconnect power relay No. 2. Using a DVOM, measure resistance of VPWR circuit between power relay No. 2 and either fuse harness connector. If resistance is less than 5 ohms, return to step 2) and perform checks for power relay No. 2. If resistance is 5 ohms or more, repair open in VPWR circuit between power relay No. 2 and splice.