DTC 78

CIRCUIT DESCRIPTION
The fuel pump speed is controlled at 2 steps (high speed, low speed) by the condition of the engine (starting, light load, heavy load), when the engine starts (STA ON), the ECM sends a Hi signal (battery positive voltage) to the fuel pump ECU (FPC terminal).
The fuel pump ECU then outputs Hi voltage (battery positive voltage) to the fuel pump so that the fuel pump operates at high speed.
After the engine starts, during idling or light loads, the ECM outputs a Low signal (about 9 V) to the fuel pump ECU, the fuel pump ECU outputs Low voltage (about 9 V) to the fuel pump and causes the fuel pump to operate at low speed.
If the intake air volume increases (high engine load), the ECM sends a Hi signal to the fuel pump ECU and causes the fuel pump to operate at high speed.





DETECTING CONDITION AND TROUBLE AREA
*: This indicates items for which "2 trip detection logic" is used. With this logic, when a logic malfunction is first detected, the malfunction is temporarily stored in the ECM memory. If the same case is detected again during the second drive test, this second detection causes the Malfunction Indicator Lamp to light up.
The 2 trip repeats the same mode a 2nd time. (However, the IG switch must be turned OFF between the 1st trip and 2nd trip).
In the Test Mode, the Malfunction Indicator Lamp lights up the 1st trip a malfunction is detected.





WIRING DIAGRAM





DIAGNOSTIC CHART























INSPECTION PROCEDURE