DTC 74

CIRCUIT DESCRIPTION:
When the ignition switch is turned to ON, the ignition relay is activated and battery positive voltage is applied to terminal B + of the ECU. When the ignition switch is turned to OFF, the ignition relay is de-energized and the power source is cut off. This power source energizes the suspension control actuator, height control valve, relay, indicator, each IC and sensor. Code 74 is set when the ECU terminal B + voltage is less than 9.5 - 10.5 volts. Inspect the ECU, battery, IC regulator (generator), ignition relay, AIR SUS fuse, HEATER fuse and the harness/connectors between the ECU and the battery.