DESCRIPTION When there is a
short to GND in the power supply for the transponder key amplifier of
the power switch, the certification ECU (smart key ECU assembly) stores
this DTC. |
DTC No. | Detection Item |
DTC Detection Condition | Trouble Area |
Note | | B278A |
Short to GND in Immobiliser System Power Source Circuit |
A
short to GND in the power supply of the transponder key amplifier of
the power switch (VC5 - VC5) detected. (1 trip detection logic*) |
- Power switch
- Certification ECU (smart key ECU assembly)
- Wire harness or connector
| DTC output confirmation operation:
- With the shift lever in P and the electrical key transmitter
sub-assembly held near the power switch, a hybrid control system start
operation is performed by pressing and holding the power switch when the
transmitter battery is depleted.
|
- *: Only output while a malfunction is present.
Vehicle Condition and Fail-safe Operation when Malfunction Detected |
Vehicle Condition when Malfunction Detected |
Fail-safe Operation when Malfunction Detected | |
Hybrid
control system cannot be started when transmitter battery is depleted
by holding transmitter near power switch and pressing and holding power
switch with shift lever in P | - | Related Data List and Active Test |
DTC No. | Data List and Active Test | |
B278A | - | WIRING DIAGRAM
 CAUTION / NOTICE / HINT
NOTICE:
- When using the Techstream with the power switch off, connect the
Techstream to the DLC3 and turn a courtesy light switch on and off at
intervals of 1.5 seconds or less until communication between the
Techstream and the vehicle begins. Then select the vehicle type under
manual mode and enter the following menus: Body Electrical / Smart Key.
While using the Techstream, periodically turn a courtesy light switch on
and off at intervals of 1.5 seconds or less to maintain communication
between the Techstream and the vehicle.
- The smart key system (for Start Function, HV Model) uses the LIN
communication system and CAN communication system. Inspect the
communication function by following How to Proceed with Troubleshooting.
Troubleshoot the smart key system (for Start Function, HV Model) after
confirming that the communication systems are functioning properly.
Click here 
- Before replacing the certification ECU (smart key ECU assembly), refer to Registration.
Click here
- After performing repairs, confirm that no DTCs are output by performing "DTC Output Confirmation Operation".
PROCEDURE |
1. | CHECK CERTIFICATION ECU (SMART KEY ECU ASSEMBLY) |
(a) Using an oscilloscope, check the waveform.
|
*a | Component with harness connected (Power Switch) |
- | - |
HINT: Perform this inspection on the power switch side. Measurement Condition: |
Tester Connection | Condition |
Tool Setting | Specified Condition | |
G117-10 (VC5) - G117-6 (AGND) |
Power switch off, electrical key transmitter sub-assembly not in cabin, within 30 seconds of power switch pressed |
2 V/DIV., 200 ms./DIV. |
Pulse generation | OK: The waveform is similar to that shown in the illustration.
| OK |
 | REPLACE POWER SWITCH |
|
NG |  | |
| 2. |
CHECK HARNESS AND CONNECTOR (CERTIFICATION ECU (SMART KEY ECU ASSEMBLY) - POWER SWITCH) |
(a) Disconnect the G40 certification ECU (smart key ECU assembly) connector.
(b) Disconnect the G117 power switch connector. (c) Measure the resistance according to the value(s) in the table below.
Standard Resistance: |
Tester Connection | Condition |
Specified Condition | |
G40-7 (VC5) - G117-10 (VC5) |
Always | Below 1 Ω | |
G40-11 (AGND) - G117-6 (AGND) |
Always | Below 1 Ω | |
G40-7 (VC5) or G117-10 (VC5) - Other terminals and body ground |
Always | 10 kΩ or higher | |
G40-11 (AGND) or G117-6 (AGND) - Other terminals and body ground |
Always | 10 kΩ or higher |
| NG |
| REPAIR OR REPLACE HARNESS OR CONNECTOR |
|
OK | | | |
| 3. |
CHECK CERTIFICATION ECU (SMART KEY ECU ASSEMBLY) |
(a) Connect the G40 certification ECU (smart key ECU assembly) connector.
(b) Connect the G117 power switch connector. (c) Measure the voltage according to the value(s) in the table below.
|
*a | Component with harness connected
(Certification ECU (Smart Key ECU Assembly)) |
- | - |
Standard Voltage: |
Tester Connection | Condition |
Specified Condition | |
G40-7 (VC5) - G40-11 (AGND) |
Power switch off, brake pedal not depressed, 30 seconds or more after driver door opened and then closed |
Below 1 V |
| OK |
| REPLACE POWER SWITCH |
| NG |
| REPLACE CERTIFICATION ECU (SMART KEY ECU ASSEMBLY) | |
