Diagnostic Aids

Enter this CIRCUIT TEST only when directed by CIRCUIT TEST C, CIRCUIT TEST J, CIRCUIT TEST PA, CIRCUIT TEST PB or CIRCUIT TEST PC. To prevent replacement of good components, be aware following non-EEC related areas may be cause of problem: battery cables and ground straps, voltage regulator, alternator and ignition switch. This test is intended to diagnose ECA, power relay, battery voltage and following harness circuits.

• Signal Return
• PWR GND
• VPWR
• KAPWR
• VREF
• Ignition Switch

Fig 1: Power Relay Circuit ID (4.6L)

Fig 2: Power Relay Ckts Terminal ID (Except 4.6L)

1) Battery Voltage Check  Turn ignition on (engine off). Measure battery voltage. If voltage is less than 10.5 volts, recharge or replace battery. If voltage is 10.5 volts or more, go to step 2).

2) Check Continuity Of PWR GND Circuit  Turn ignition off. Wait 10 seconds. Disconnect ECA, and inspect connector pins. If ECA connector pins are damaged, loose or corroded, repair as necessary. Install Break-out Box (T83L-50-EEC-IV), leaving ECA connected. Measure resistance between test pins No. 40 and 60 at breakout box and negative battery terminal. If resistance is 5 ohms or more, repair open in PWR GND circuit. Remove breakout box, and repeat QUICK TEST  . If both resistances are less than 5 ohms, go to step 3).

3) Check For Open Between SIG RTN & PWR GND Circuits At ECA  Ensure ignition is turned off. With breakout box installed and ECA connected, set DVOM on 200-ohm scale. Measure resistance between test pin No. 46 and test pins No. 40 and 60 at breakout box. If readings are 5 ohms or more, disconnect ECA connector, and inspect it for corrosion and damaged pins. Repair as necessary. If fault is still present, replace ECA and repeat QUICK TEST  . If readings are less than 5 ohms, go to step 4).

4) Check Continuity Of SIG RTN Circuit  Ensure ignition is turned off. Measure resistance between test pin No. 46 at breakout box and SIG RTN terminal at self-test connector. If resistance is 5 ohms or more, repair open in SIG RTN circuit. Remove breakout box, and repeat QUICK TEST  . If reading is less than 5 ohms, go to step 5).

5) Check KAPWR Circuit Voltage At EEC Power Relay  Turn ignition off. Locate relay block in engine compartment. Disconnect EEC power relay from relay block. Turn ignition on. Measure voltage between negative battery terminal and KAPWR terminal at EEC power relay connector. If voltage is 10.5 volts or less, check KAPWR circuit between EEC power relay and battery power for open circuit. If voltage is 10.5 volts or more, go to step 6).

6) Check Ignition Circuit Voltage At EEC Power Relay  Ensure EEC power relay is disconnected. Turn ignition on. Measure voltage between negative battery terminal and IGNITION terminal at EEC power relay connector. If voltage is less than 10.5 volts, check for open in ignition switch circuits. Repair wiring, and repeat QUICK TEST  . If voltage is 10.5 volts or more, go to step 7).

7) Check PWR GND Circuit Continuity  Turn ignition off, and wait 10 seconds. With ECA connected to breakout box, measure resistance between negative battery terminal and PWR GND terminal at EEC power relay connector. If resistance is 10 ohms or more, repair open circuit in ground circuit. Repeat QUICK TEST  . If reading is less than 10 ohms, go to step 8).

8) Check VPWR Circuit Continuity  Turn ignition off. Measure resistance between test pins No. 37 and 57 (VPWR) at breakout box and VPWR terminal of EEC power relay connector. If resistance is 5 ohms or more, repair VPWR open circuit between EEC power relay and ECA. Repeat QUICK TEST  . If reading is less than 5 ohms, go to step 9).

9) Check VPWR Circuit Voltage  Turn ignition off. Install EEC power relay. Turn ignition on. With ECA connected, measure voltage between test pins No. 37 and 57 (VPWR) and test pins No. 40 and 60 (PWR GND) and 46 (SIG RTN) at breakout box. If voltage is 10.5 volts or more, repair circuit between ECA and EEC power relay. Repeat QUICK TEST  . If voltage is less than 10.5 volts, replace EEC power relay. Repeat QUICK TEST.