Test B: EEC-V Power Relay: Testing

1) VPWR Check At Fuel Injector Failed In Test C: Check For Open VPWR Circuit

Turn ignition switch to OFF position. Disconnect fuel injector harness connector. Disconnect scan tool. Disconnect PCM power relay (PCM power relay No. 1 on LS and Thunderbird). Using a DVOM, measure resistance of VPWR circuit between fuel injector harness connector and PCM power relay cavity. See Fig 1-Fig 3 . If resistance is less than 5 ohms, reconnect fuel injector and go to next step. If resistance is 5 ohms or more, repair open in VPWR circuit between PCM power relay and fuel injector.

Fig 1: Identifying Power Relay Circuits (Escape, Focus, Sable & Taurus)
Courtesy of FORD MOTOR CO.

Fig 2: Identifying Power Relay Circuits (LS & Thunderbird)
Courtesy of FORD MOTOR CO.

Fig 3: Identifying Power Relay Circuits (All Others)
Courtesy of FORD MOTOR CO.

2) Check B+ & IGN START/RUN Voltage To PCM Power Relay

Ensure ignition switch is turned to OFF position and PCM power relay is disconnected. Using a DVOM, measure voltage between negative battery terminal and B+ terminal at PCM power relay cavity. Record voltage measurement. Turn ignition switch to ON position. Using a DVOM, measure voltage between negative battery terminal and IGN START/RUN terminal at PCM power relay cavity. If both voltage measurements are more than 10.5 volts, go to next step. If either voltage measurement is 10.5 volts or less, turn ignition switch to OFF position. Check B+ or IGN START/RUN circuits for open. Check condition of related fuse(s) or diode. If okay, repair open in affected circuit. If fuse is blown, check IGN START/RUN or B+ and VPWR circuits for short to ground before replacing fuse.

3) Check Ground Circuit To PCM Power Relay

Using a DVOM, measure voltage between chassis ground terminal and B+ terminal at PCM power relay cavity. If voltage is more than 10.5 volts, replace PCM 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: PCM power relay No. 2 (also referred to as COPS and HO2S relay) supplies VPWR to 2 separately fused circuits. To determine fuse locations, see WIRING DIAGRAMS .

5) LS & Thunderbird VPWR Check Failed: Check Fuse
Remove and inspect suspect VPWR fuse to component where VPWR check failed. If suspect fuse is okay, go to next step. If suspect fuse is blown, check VPWR circuit for short to ground between blown fuse and appropriate component. Repair as necessary and replace VPWR fuse.

6) Check For Power To Other VPWR Circuit Fuse Connected To PCM Power Relay No. 2

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 PCM power relay No. 2. If both voltage measurements are more than 10.5 volts, repair open between fuse and component where VPWR check failed. 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 10.5 volts or less, repair open in VPWR circuit between fuse and splice.

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

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