GF83.70-D-4215H ZUH Control Unit, Component Description

GF83.70-D-4215H ZUH Control Unit, Component Description
MODEL 906.111 /113 /131 /133 /135 /153 /155 /211 /213 /231 /233 /235 /253 /255 /611 /613 /631 /633 /635 /637 /653 /655 /657 /711 /713 /731 /733 /735
- with CODE (HZ9) Heater booster, diesel

MODEL 906.611 /613 /631 /633 /635 /637 /653 /655 /657 /711 /713 /731 /733 /735
- with CODE (HZ5) 10 kW warm water auxiliary heater with timer







20 Heater booster unit
N33/2 Warm water auxiliary heater 2 control unit

Location
The warm water auxiliary heater 2 control unit is integrated in the heater booster heater unit, which is located at the vehicle underside between the left vehicle rocker panel and the vehicle tank at the level of the B-pillar.

Task
The warm water auxiliary heater 2 control unit is the master control unit for the heater booster (ZUH) system. It controls the following functions:
- Monitoring signal from temperature sensor (N33/2b1)
- Monitoring signal from flame sensor (N33/2b2)
- Monitoring signal from the overheating sensor (N33/2b3)
- Actuation of blower motor (N33/2m1) of ZUH combustion air blower
- Actuation of glow pin (N33/2r1)
- Actuation of metering pump (M46/4)
- Actuation of circulation pump (M13/4)
- Actuation of the red or yellow light emitting diode (LED) integrated in the stationary heater switch (S46/10)
- Fault shutoff in the event of exceptional operating conditions such as flame-out, undervoltage or overvoltage or failure of internal coolant temperature detection
- Fault shutoff and fault interlock in the event of overheating
- Communication with the warm water auxiliary heating control unit (N33/3), with code (HZ5) 10 kW warm water auxiliary heater with timer or with code (H12) Warm water auxiliary heater

To do this, the warm water auxiliary heater 2 control unit reads in the following components:
- Temperature sensor
- Flame sensor
- Overheating sensor
- Stationary heater switch
- Warm water auxiliary heater control unit, with code (HZ5) 10 kW warm water auxiliary heater with timer or (H12) Warm water auxiliary heater

Moreover, the warm water auxiliary heater 2 control unit reads in the following messages from the related components via the Controller Area Network bus class B (interior) (CAN-B):
- "STH_ZHZ_EIN (heater booster function is activated)" from warm water auxiliary heating control unit, with code (HZ5) 10 kW warm water auxiliary heater with timer or (H12) Warm water auxiliary heater
- "T_MOT (engine coolant temperature)" from the coolant temperature sensor (B11/4) via the instrument cluster
- "T_INNEN_KLA" (interior temperature)" from the interior temperature sensor (S98b1), with code (HH9) Regulated air conditioning (Tempmatic), via the KLA control and operating unit (S98)
- "TEMP_SOL (specified temperature value)" from the KLA control and operating unit

After evaluating the input signals, the warm water auxiliary heater 2 control unit actuates the following components for the control of the heater booster heater unit via discrete lines:
- Blower motor of ZUH combustion air blower
- Glow pin
- Metering pump
- Circulation pump

Moreover, the warm water auxiliary heater 2 control unit places the following messages for the related components on the CAN-B:
- "ZHZ_EIN (heater booster switched on)" to the DBE control unit (N70), with code (LD0) Dome lamp with reading lamp at driver/front passenger, to the warm water auxiliary heating control unit, with code (HZ5) 10 kW warm water auxiliary heater with timer or with code (H12) Warm water auxiliary heater, and to the KLA control and operating unit
- "ZHZ_ZWP_EIN" (switch on heater booster for additional water pump (circulation pump))" to the warm water auxiliary heating control unit, with code (HZ5) 10 kW warm water auxiliary heater with timer or with code (H12) Warm water auxiliary heater, and to the KLA control and operating unit