DESCRIPTION
This DTC is stored when the engine switch power source supply line is open or shorted.
DTC Code |
DTC Detection Condition |
Trouble Area |
---|---|---|
B278A |
The engine switch power source supply line is open or shorted. |
|
WIRING DIAGRAM
CAUTION / NOTICE / HINT
NOTICE:
Before replacing the certification ECU, refer to Registration (See page ).
PROCEDURE
1. |
CHECK HARNESS AND CONNECTOR (CERTIFICATION ECU - ENGINE SWITCH) |
(a) Disconnect the F79 ECU connector.
(b) Disconnect the F71 switch connector.
(c) Measure the resistance according to the value(s) in the table below.
Standard Resistance:
Tester Connection |
Condition |
Specified Condition |
---|---|---|
F79-28 (VC5) - F71-14 (VC5) |
Always |
Below 1 Ω |
F79-36 (AGND) - F71-8 (AGND) |
||
F79-28 (VC5) or F71-14 (VC5) - Body ground |
Always |
10 kΩ or higher |
F79-36 (AGND) or F71-8 (AGND) - Body ground |
NG |
REPAIR OR REPLACE HARNESS OR CONNECTOR |
|
2. |
CHECK CERTIFICATION ECU |
(a) Using an oscilloscope, check the waveform. Measurement Condition
OK: Waveform is output normally (refer to illustration). Text in Illustration
|
|
OK |
REPLACE ENGINE SWITCH |
NG |
REPLACE CERTIFICATION ECU |
Removal
REMOVAL
CAUTION / NOTICE / HINT
NOTICE:
Make sure to release the vacuum from the brake booster before removing the master
cylinder from the brake booster.
PROCEDURE
1. DRAIN BRAKE FLUID
NOTICE:
Wash off brake fluid immediately if it comes in contact w ...
Problem Symptoms Table
PROBLEM SYMPTOMS TABLE
HINT:
Use the table below to help determine the cause of problem symptoms. If multiple
suspected areas are listed, the potential causes of the symptoms are listed in order
of probability in the "Suspected Area" column of ...