DESCRIPTION
This DTC is stored when the engine switch power source supply line is open or shorted.
DTC No. |
DTC Detection Condition |
Trouble Area |
---|---|---|
B278A |
Engine switch power source supply line is open or shorted. |
|
WIRING DIAGRAM
CAUTION / NOTICE / HINT
NOTICE:
If the certification ECU (smart key ECU assembly) is replaced, register the key (See page ).
PROCEDURE
1. |
CHECK DTC OUTPUT |
(a) Clear the DTCs (See page ).
(b) Recheck for DTCs (See page ).
OK:
DTC B278A is not output.
OK |
USE SIMULATION METHOD TO CHECK |
|
2. |
CHECK HARNESS AND CONNECTOR (CERTIFICATION ECU - ENGINE SWITCH) |
(a) Disconnect the certification ECU (smart key ECU assembly) connector.
(b) Disconnect the engine switch connector. |
|
(c) Measure the resistance according to the value(s) in the table below.
Standard Resistance:
Tester Connection |
Condition |
Specified Condition |
---|---|---|
D25-28 (VC5) - D13-14 (VC5) |
Always |
Below 1 Ω |
D25-36 (AGND) - D13-8 (AGND) |
Always |
Below 1 Ω |
D25-28 (VC5) - Body ground |
Always |
10 kΩ or higher |
D25-36 (AGND) - Body ground |
Always |
10 kΩ or higher |
*1 |
Front view of wire harness connector (to Certification ECU (Smart Key ECU Assembly)) |
*2 |
Front view of wire harness connector (to Engine Switch) |
NG |
REPAIR OR REPLACE HARNESS OR CONNECTOR |
|
3. |
CHECK CERTIFICATION ECU (SMART KEY ECU ASSEMBLY) |
(a) Reconnect the certification ECU (smart key ECU assembly) connector.
(b) Reconnect the engine switch connector.
(c) Using an oscilloscope, check the waveform.
Waveform (Reference):
Item |
Content |
---|---|
Tester Connection |
D25-28 (VC5) - D25-36 (AGND) |
Tool Setting |
2 V/DIV., 200 ms./DIV. |
Condition |
|
OK:
Waveform is output normally (see illustration)
Result |
Proceed to |
---|---|
NG |
A |
OK (for 2GR-FE) |
B |
OK (for 1AR-FE) |
C |
*1 |
Component with harness connected (Certification ECU (Smart Key ECU Assembly)) |
*2 |
GND |
A |
REPLACE CERTIFICATION ECU (SMART KEY ECU ASSEMBLY) |
B |
REPLACE ENGINE SWITCH |
C |
REPLACE ENGINE SWITCH |
Fail-safe Chart
FAIL-SAFE CHART
If a problem occurs in the power steering system, the power steering assist will
be stopped or the amount of power assist will be decreased to protect the system.
Power Steering System
Malfunction
Fail-safe Operation
...
Reassembly
REASSEMBLY
PROCEDURE
1. REPAIR INSTRUCTION
2. INSTALL REAR DOOR OUTSIDE MOULDING
3. INSTALL REAR DOOR LOWER OUTSIDE STRIPE
4. INSTALL NO. 2 BLACK OUT TAPE
5. INSTALL REAR DOOR OUTSIDE STRIPE
6. INSTALL REAR DOOR UPPER WINDOW FRAME MOULDIN ...
Diagnostic Trouble Code Chart
DIAGNOSTIC TROUBLE CODE CHART
If a trouble code is displayed during the DTC check, check the trouble areas
listed for that code in the table below and proceed to the appropriate page.
Cruise Control System
DTC Code
Detection Item
...