1A-28 Engine Control System ECM wiring diagram (4) Characteristics of Circuit If multiple DTC21, 23, 41, and 32 are displayed, the ground wire 1 must be checked. If multiple DTC21, 23, and 41 are displayed, the ground wire 2 must be checked. If multiple DTC21 and 23 are displayed, the ground wire 3 must be checked. Multiple DTC is generated when several troubles (failures) occur. When multiple sensors or switches share a ground, or an open wiring or short occurs on the share power supply or ground, DTCs with respect to related sensors or switches are displayed. If several DTCs are displayed, it is necessary to inspect the shared power supply or ground for open wiring or short.
The harness 1 in above figure is a common ground for the engine coolant temperature sensor, fuel temperature sensor, intake air temperature sensor and intake air pressure sensor. In the event of the open wiring in the wire 1, DTC 21, 23, 41 and 32 are displayed at the same time. In the event of the open wiring in the wire 2, DTC 21, 23, and 41 are displayed at the time. Like this, the case where two or more DTC’s are displayed is the multiple DTC.
3 2 1 ECM Sensor Ground C-1 C-12 C-15 C-9 C-5 C-4 0.5 0.5 0.5 Y/G W/ L/W GRN 0.3 0.5 0.3 0.5 0.3 0.5 BLU/ W/ R/G W/ R/Y W/ RED GRN GRN GRN GND GND GND SIG SIG SIG Engine Coolant Fuel Temperature Intake Air Intake Air Temperature Sensor Temperature Pressure Sensor Sensor Sensor LNW21ALF000601-X DTC Sensor actuator (detection item) 21 Engine coolant temperature sensor Connector not connected, open wiring or short of harness, failure of main unit 23 Intake air temperature sensor 41 Fuel temperature sensor 32 Intake air pressure sensor