Power Circuits

With ignition off. Disconnect Electronic Control Unit (ECU) connector(s). Use a DVOM to probe ECU terminal connector. Check that battery (back-up power) voltage is present at ECU terminal A3 (White/Blue wire). Turn ignition on and ensure battery voltage is present at terminals A4 and A9 (Red wire). See appropriate wiring diagram in WIRING DIAGRAMS article. Repair circuits as required.