Test A2 - Vehicle Battery

Fig 1: Vehicle Battery Circuits Diagram

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
• Ground
• VPWR
• KAPWR
• VREF
• Ignition

1. Battery Voltage Check. Turn key on with engine off. Set DVOM on 20-volt scale and measure voltage across battery terminals. If reading is less than 10.5 volts, charge or replace battery. If reading is greater than 10.5 volts, go to next step.
2. Checking EEC Ground Circuit. Turn key off and wait 10 seconds. Inspect ECA connector and pins. Install breakout box and connected ECA to breakout box. Set DVOM on 200-ohm scale and measure resistance between test pin No. 40 of breakout box and negative post on battery. Also measure resistance between test pin No. 60 of breakout box and negative post on battery. If greater than 5 ohms, remove breakout box, reconnect ECA and repair open EEC ground circuit. Repeat QUICK TEST. If both readings are less than 5 ohms, go to next step.
3. Checking ECA Ground Insolation. Turn key off and wait 10 seconds. Install breakout box and connect ECA to it. Set DVOM on 200 ohm scale. Measure resistance between test pins No. 46 and 40 and between test pins No. 46 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.
4. Checking Continuity of Signal Return 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 signal return circuit in SELF-TEST connector. If reading is greater than 5 ohms, repair open circuit and repeat quick test. If reading is less than 5 ohms, go to next step.
5. Checking KAPWR Circuit. Turn key on with engine off. Install breakout box and connect ECA. Set DVOM on 20-volt scale. Measure voltage between battery negative post and test pin No. 1 at breakout box. If reading is less than 10.5 volts, check KAPWR and VPWR circuits for shorts to ground. Also check KAPWR circuit from EEC power relay to battery positive post for open circuit. Remove breakout box, reconnect ECA and repeat quick test. If reading is 10.5 volts or more, go to next step.
6. Ignition Circuit Voltage. Turn key on, leaving engine off. With breakout box and ECA connected, set DVOM on 20-volt scale. Measure voltage between battery negative post and ignition circuit at EEC power relay. If reading is less than 10.5 volts, check for open ignition switch circuits. Repair wiring and repeat QUICK TEST. If reading is 10.5 volts or more, go to next step.
7. Checking EEC Power Relay Ground Circuit. Turn key off and wait 10 seconds. Install breakout box and connect ECA. Set DVOM on 200-ohm scale. Measure voltage between battery negative post and EEC relay ground. If reading is greater than 5 ohms, repair wiring in ground circuit. Repeat QUICK TEST. If reading is less than 5 ohms, go to next step.
8. Checking Power Circuit (VPWR) At EEC Power Relay. Turn key on, leaving engine off. Install breakout box and connect ECA. Set DVOM on 20-volt scale, measure voltage between battery negative post and VPWR circuit at EEC power relay. If reading is 10.5 volts or greater, repair open in VPWR circuit. If VPWR circuit is okay, repair short to ground in VPWR circuit. If reading is less than 10.5 volts, replace EEC power relay. Repeat quick test.