THEFT DETERRENT / KEYLESS ENTRY ENTRY AND START SYSTEM(for Start Function) B278A Short to GND in Immobiliser System Power Source Circuit
DESCRIPTION
When there is a short to GND in the power supply for the transponder key amplifier of the engine 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 | Short to GND detected in the power supply of the transponder key amplifier of the engine switch (VC5 - VC5) (1 trip detection logic*). | ·
Harness or connector ·
Engine switch ·
Certification ECU (smart key ECU assembly) |
DTC Output Confirmation Operation:
With the shift state park (P) and the electrical key transmitter sub-assembly held near the engine switch, an engine start operation is performed by pressing and holding the engine switch when the transmitter battery is depleted. |
*: Only output while a malfunction is present.
| Vehicle Condition when Malfunction Detected | Fail-safe Operation when Malfunction Detected |
|---|---|
| Engine cannot be started when transmitter battery is depleted by holding electrical key transmitter sub-assembly near engine switch and pressing and holding engine switch with shift state park (P). | - |
| DTC No. | Data List and Active Test |
|---|---|
| B278A | - |
WIRING DIAGRAM
CAUTION / NOTICE / HINT
- NOTICE:
- ·
When using the GTS with the engine switch off, connect the GTS to the DLC3 and turn a courtesy light switch on and off at intervals of 1.5 seconds or less until communication between the GTS and the vehicle begins. Then select Model Code "KEY REGIST" under manual mode and enter the following menus: Body Electrical / Entry&Start. While using the GTS, periodically turn a courtesy light switch on and off at intervals of 1.5 seconds or less to maintain communication between the GTS and the vehicle.
·The entry and start system (for Start Function) uses the LIN communication system and CAN communication system. Inspect the communication function by following How to Proceed with Troubleshooting. Troubleshoot the entry and start system (for Start Function) after confirming that the communication systems are functioning properly.
·Before replacing the certification ECU (smart key ECU assembly), refer to the Service Bulletin.
·After repair, confirm that no DTCs are output by performing "DTC Output Confirmation Operation".
PROCEDURE
Using an oscilloscope, check the waveform.
| *a | Component with harness connected
(Engine Switch) |
*b | Waveform |
- OK:
Tester Connection Condition Tool Setting Specified Condition N162-10 (VC5) - N162-6 (AGND) Engine switch off, electrical key transmitter sub-assembly not in cabin, within 30 seconds after engine switch pressed 2 V/DIV., 200 ms./DIV. Pulse generation
(See waveform)
- Result:
Proceed to OK NG
OK
for 7GR-FKS:
for 1GD-FTV:
NG
Disconnect the N156 certification ECU (smart key ECU assembly) connector.
Disconnect the N162 engine switch connector.
Measure the resistance according to the value(s) in the table below.
- Standard Resistance:
Tester Connection Condition Specified Condition N156-7 (VC5) - N162-10 (VC5) Always Below 1 Ω N156-7 (VC5) or N162-10 (VC5) - Other terminals and body ground Always 10 kΩ or higher N156-11 (AGND) - N162-6 (AGND) Always Below 1 Ω
Reconnect the N156 certification ECU (smart key ECU assembly) connector.
Reconnect the N162 engine switch connector.
- Result:
Proceed to OK NG
OK
NG
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 N162-7 (VC5) - N162-11 (AGND) Engine switch off, brake pedal not depressed, 30 seconds or more after driver door opened and then closed Below 1 V
- Result:
Proceed to OK NG
OK
for 7GR-FKS:
for 1GD-FTV:
NG