Power Distribution Relay: Description and Operation
Functions of the combination relay N10, N10/2
1. Triggering the flash pulse for the direction indicators
2. Triggering the flash pulse for the hazard warning flashers
3. Recognizing failure of a bulb in the direction indicators without trailer
4. Recognizing failure of a bulb in the direction indicators with trailer
5. Controlling the wiper system
6. Controlling and monitoring the rear window defroster
1. Triggering the flash pulse for the direction indicators
Voltage is supplied to the combination relay N10, N10/2, terminal 49 by fuse 6, terminal 15 through the hazard warning light switch S6 from position 1 of the ignition/starter switch S2/1 or of the glow/starter switch S2/2. The functions of left or right turn signal indicators can be activated at the combination switch S4.
The combination switch is connected via terminal 49a to the switch contact of the turn signal switch S4s1 in the combination switch. The electronics of the combination relay activates the turn signal pulse as soon as the circuit of the left-hand or right-hand turn signal lights is closed to ground via the switch contact of the turn signal switch S4s1. The turn signal lights are actuated via terminal 49a by the combination relay with a uniform current pulse sequence and flash.
2. Triggering the flash pulse for the hazard warning flashers
As operation of the hazard warning flashers must also be assured when the car key is withdrawn, the position of the ignition/starter switch S2/1 or of the glow/starter switch S2/2 is of no significance. When the hazard warning switch S6 is operated, voltage is supplied to the combination relay N10, N10/2, terminal 49 by the fuse 4, terminal 30.
The electronics of the combination relay activate the flash pulse as soon as the circuit of the left-hand and of the right-hand turn signal lights is closed to ground via the switch contact of the hazard warning switch. All the turn signal lights are actuated via 49a by the combination relay with a uniform current pulse sequence and flash.
3. Recognizing failure of a bulb in the direction indicators without trailer
The electronics of the combination relay N10, N10/2 is equipped with a monitoring stage which monitors the flash current in order to recognize a fault in a bulb.
The monitoring stage is designed to monitor two bulbs. The fault in a bulb reduces the flash current by about half, this is detected by the monitoring stage which doubles the flash frequency as a warning.
4. Recognizing failure of a bulb in the direction indicators with trailer
If the car is equipped with a towing device, terminal 1 of the combination relay N10, N10/2 is connected to terminal 5 of the trailer recognition control unit N28/1.
The combination relay recognizes that a trailer is connected by means of this link and the monitoring stage adapts to monitoring three bulbs. The failure of a bulb when towing a trailer also increases the flash frequency as a warning.
5. Controlling the wiper system
The combination relay N10, N10/2 controls
- the wipe-wash operation with wiper off delay
and
- and the intermittent wipe of the wiper system.
The operations of the wiper system are activated with the combination switch S4. The wiper motor M6/1 is actuated directly via the combination switch S4 in two stages for continuous wiping.
From position 1 of the ignition/starter switch S2/1 or of the glow/starter switch S2/2, voltage is connected from fuse 15, terminal at the combination switch S4, the wiper motor M6/1 and combination relay N10, N10/2 for operating the wiper system. The operations of the wiper system can then be activated at the combination switch.
Wipe-wash operation with wiper off delay
The wipe-wash operation is activated with the washer switch S4s4 in the combination switch. Voltage is connected to terminal 86 of the combination relay N10, N10/2 and to the washer pump M5/1 through the closed switch contact of the washer switch.
For wipe-wash operation. voltage is connected through the washer switch S4s4 to the electronics of the combination relay N10, N10/2 and the washer pump M5/1. The washer switch must be operated for a longer period for the wipe-wash mode. The wiper motor and the washer pump then operate during the entire period the switch is operated. Once the washer switch is released, the wiper motor is actuated by the combination relay for wiping the windshield which may still be wet, for a further three sweeps of the wipers.
Intermittent wiping
For intermittent wipe, the wiper control at the combination switch S4 must be in position 1, intermittent wipe switch contact S4s7 closed. The intermittent wipe is activated as soon as the switch contact S4s7 is closed and voltage is supplied to the electronics through terminal J of the combination relay N10, N10/2. The wiper M6/1 is operated with a uniform current pulse sequence through terminal 31b of the combination relay. Each current pulse produces a sweep of the wiper.
6. Controlling and monitoring the rear window defroster
Switching on and switching off of the rear window defroster R1 is controlled through the combination relay N10, N10/2. The load current for operating the rear window defroster is switched by fuse 16, terminal 30 through terminal 30 of the combination relay and the power output terminal 87 to the resistor of the rear window defroster.
The rear window defroster can be switched on with the rear window defroster switch S14 from position 1 of the ignition/starter switch S2/1 or of die glow/starter switch S2/2. The switch is designed as an on/off push-button switch.
In switch position On, voltage is supplied by fuse 8, terminal 15R through terminal E to the electronics of the combination relay. The electronics closes the circuit between terminal 30 and terminal 87 and at the same time actuates the LED function indicator of the rear window defroster as soon as the switch is released.
The rear window defroster is switched off automatically by the electronics after an on period of 15 to 20 minutes. It can also be switched off before this on period has elapsed, however, with the rear window defroster switch. In the Off position, voltage is switched from fuse 8, terminal 15R through terminal A to the combination relay.
The electronics in the combination relay monitors the battery voltage and the voltage supply through the ignition/starter switch S2/1 or the glow/starter switch S2/2 when the rear window defroster is on.
The rear window defroster is switched off automatically as soon as the ignition/starter or glow/starter switch is in position 0 or if the battery voltage drops below 10.6 V.
If the rear window defroster is switched off because of insufficient voltage, this is indicated by the LED function indicator in the rear window defroster switch S14 flashing. The rear window defroster is switched on again automatically as soon as the battery voltage has increased by 0.8 to 1 V beyond the cut-off level.