Inspection of BCM and Its Circuits
Inspection of BCM and its CircuitsBCM and its circuits can be checked at BCM wiring couplers by measuring voltage and resistance.
CAUTION: BCM cannot be checked by itself. It is strictly prohibited to connect voltmeter or ohmmeter to BCM with couplers disconnected from it.
Voltage Check
1. Disconnect negative cable (-) at battery.
2. Remove BCM.
3. Connect BCM connector as shown in the figure.
4. Check voltage at each terminal of couplers connected.
NOTE:
- As each terminal voltage is affected by the battery voltage, confirm that it is 11V or more when ignition switch is ON.
- Pulse signal cannot be measured by voltmeter. It can be measured by oscilloscope.
BCM connector (viewed from harness side)
As the input signal of the switch described below repeats ON and OFF at every 10 ms as shown in the figure below, measurement of the terminal voltage will indicate an abnormal voltage value. Also, if no signal input/output occurs for 10 seconds or longer while the ignition switch remains OFF, the stand-by current is controlled by reducing its ON time (Sleep mode).
Applicable switch
- Manual door lock/unlock switch
- Door key cylinder lock/unlock switch
- Auto-on headlight switch
- Diagnosis switch
- Windshield washer level switch
Ter. G53-1 - G53-16:
Terminal "G53"
Ter. G54-1 - G54-10:
Ter. G54-11 - G54-22:
Terminal "G54"
Ter. G55-1 - G55-16:
Terminal "G55"
Ter. G56-1 - G56-12:
Terminal "G56"
Ter. G57-1 - G57-2:
Terminal "G57"
1. Reference waveform No.1
Passenger side or driver side door lock actuator UNLOCK signal (2) with manual unlock switch or door key cylinder unlock switch signal (1)
2. Reference waveform No.2
Door lock actuator LOCK signal (2) with manual lock switch or door key cylinder lock switch signal (1)
3. Reference waveform No.3
Keyless entry receiver LOCK / UNLOCK signal
4. Reference waveform No.4
Auto-on headlight switch position signal
5. Reference waveform No.5
Diagnosis switch position signal
6. Reference waveform No.6
BCM CAN communication line signal