Relay Control System: Fail-Safe

CAN COMMUNICATION CONTROL 

When CAN communication with ECM and BCM is impossible, IPDM E/R performs fail-safe control. After CAN communication recovers normally, it also returns to normal control.

If No CAN Communication Is Available With ECM 

Control part	Fail-safe operation
Cooling fan	Transmits the pulse duty signal (PWM signal) 100% when the ignition switch is turned ON. Transmits the pulse duty signal (PWM signal) 0% when the ignition switch is turned OFF.
A/C compressor	A/C relay OFF
Alternator	Transmits the power generation command signal (PWM signal) 0%

If No CAN Communication Is Available With BCM 

Control part	Fail-safe operation
Headlamp	Turns ON the headlamp low relay when the ignition switch is turned ON Turns OFF the headlamp low relay when the ignition switch is turned OFF Headlamp high relay OFF
Parking lamp License plate lamp Illumination Tail lamp Side marker lamp	Turns ON the tail lamp relay when the ignition switch is turned ON Turns OFF the tail lamp relay when the ignition switch is turned OFF
Front wiper motor	The status just before activation of fail-safe control is maintained until the ignition switch is turned OFF while the front wiper is operating at LO or HI speed. The wiper is operated at LO speed until the ignition switch is turned OFF if the fail-safe control is activated while the front wiper is set in the INT mode and the front wiper motor is operating. Return automatically wiper to stop position when ignition switch is turned ON if fail-safe control is activated while front wiper motor is operated and wiper stops in the other position than stop position.
Front fog lamp	Front fog lamp relay OFF
Horn	Horn OFF
Ignition relay	The status just before activation of fail-safe is maintained.
Starter motor	Starter control relay OFF

IGNITION RELAY MALFUNCTION DETECTION FUNCTION 

• IPDM E/R monitors the voltage at the contact circuit and excitation coil circuit of the ignition relay inside it.
• IPDM E/R judges the ignition relay error if the voltage differs between the contact circuit and the excitation coil circuit.
• If the ignition relay cannot turn OFF due to contact seizure, it activates the tail lamp relay for 10 minutes to alert the user to the ignition relay malfunction when the ignition switch is turned OFF.

Voltage judgment		IPDM E/R judgment	Operation
Ignition relay contact side	Ignition relay excitation coil side
ON	ON	Ignition relay ON normal	-
OFF	OFF	Ignition relay OFF normal	-
ON	OFF	Ignition relay ON stuck	Detects DTC "B2098: IGN RELAY ON CIRC" Turns ON the tail lamp relay for 10 minutes
OFF	ON	Ignition relay OFF stuck	Detects DTC "B2099: IGN RELAY OFF CIRC"

FRONT WIPER PROTECTION FUNCTION 

IPDM E/R detects front wiper stop position by a front wiper stop position signal.

When a front wiper stop position signal is in the conditions listed below, IPDM E/R stops power supply to wiper after repeating a front wiper 10 seconds activation and 20 seconds stop.

Ignition switch	Front wiper switch	Front wiper stop position signal
ON	OFF	The front wiper stop position signal (stop position) cannot be input for 10 seconds.
	ON	The front wiper stop position signal does not change for 10 seconds.

STARTER MOTOR PROTECTION FUNCTION 

IPDM E/R turns OFF the starter control relay to protect the starter motor when the starter control relay remains active for 90 seconds.