Test B - Checking Vehicle Battery

Fig 1: Power Relay Circuits

To prevent replacement of good components, be aware that the following non-EEC related areas may be at fault: battery cables and ground straps, voltage regulator, alternator, or ignition switch. This test is intended to diagnose the ECA, power relay, battery voltage and the following harness circuits:

• Signal Return
• STO
• STI
• PWR GND
• VPWR
• KAPWR
• VREF
• Ignition

1. Battery Voltage Check  Turn key on, leaving engine off. Set DVOM on 20-volt scale and measure voltage across battery terminals. If reading is less than 10.5 volts, service or replace discharged battery. If reading is 10.5 volts or more, go to next step.
2. Check Continuity of PWR GND Circuit  Turn key off and wait 10 seconds. Inspect ECA connector and pins. Install breakout box, leave ECA connected. Set DVOM on 200-ohm scale and measure resistance between test pins No. 40 and 60 at the breakout box and battery negative post. If readings are greater than 5 ohms, repair open in PWR GND circuit. Remove breakout box, reconnect components and repeat QUICK TEST PROCEDURES . If both readings are less than 5 ohms, go to next step.
3. Check For Open Between SIG RTN & PWR GND Circuits at ECA  With breakout box installed and ECA connected, turn key off and wait 10 seconds. Set DVOM on 200-ohm scale. Measure resistance between test pin No. 46 and test pins No. 40 and 60 at breakout box. If both readings are less than 5 ohms, go to next step. If readings are greater than 5 ohms, disconnect ECA connector and inspect for corrosion or damaged pins. Repair if necessary. If fault is still present, replace ECA and repeat QUICK TEST PROCEDURES .
4. Check Continuity of SIG RTN Circuit  With breakout box installed and ECA connected, turn key off and wait 10 seconds. Set DVOM on 200-ohm scale. Measure resistance between test pin No. 46 at breakout box and SIG RTN circuit at the Self-Test connector. If resistance is greater than 5 ohms, repair open in SIG RTN circuit. Remove breakout box, reconnect components and repeat QUICK TEST PROCEDURES . If reading is less than 5 ohms, remove breakout box, connect ECA and go to next step.
5. Check KAPWR Circuit Voltage at EEC Power Relay  Turn key on, leaving engine off. With ECA connected, set DVOM on 20-volt scale. Measure voltage between battery negative post and KAPWR circuit at EEC power relay harness connector. If reading is less than 10.5 volts, check KAPWR circuit from EEC power relay to battery positive post for open circuit. If reading is 10.5 volts or more, go to next step.
6. Check Ignition Circuit Voltage at EEC Power Relay  Turn key on, leaving engine off. Ensure ECA is connected, set DVOM on 20-volt scale. Measure voltage between battery negative post and IGNITION circuit at EEC power relay vehicle harness connector. If reading is less than 10.5 volts, check for open in ignition switch circuits. Repair wiring and repeat QUICK TEST PROCEDURES . If reading is 10.5 volts or more, go to next step.
7. Check PWR GND Circuit Continuity  Turn key off and wait 10 seconds. With ECA connected and DVOM on 200-ohm scale, measure resistance between battery negative post and PWR GND circuit at EEC power relay vehicle harness connector. If resistance is 5 ohms or more, repair wiring in ground circuit. Repeat QUICK TEST PROCEDURES . If reading is less than 5 ohms, go to next step.
8. Check VPWR Circuit at EEC Power Relay  Turn key on, leaving engine off. With ECA connected and DVOM on 20-volt scale, measure voltage between battery negative post and VPWR circuit at EEC power relay vehicle harness connector. If reading is 10.5 volts or more, repair open or short to ground in VPWR circuit between ECA and EEC power relay. Reconnect components and repeat QUICK TEST PROCEDURES . If reading is less than 10.5 volts, replace EEC power relay. Repeat QUICK TEST.