Repairing auxiliary coolant heater -B4W/D4W- — VW

Repairing auxiliary coolant heater -B4W/D4W-
Caution
Before working on the auxiliary heater and/or the fuel system, pull out the appropriate fuses
Current flow diagrams, Electrical fault finding and Fitting locations
.
Note
A manufacturer's plate is attached to the heater unit. This plate gives details of the heater unit type installed in the vehicle: Petrol B4W
Fig.
or diesel D4W
Fig.
The coolant circuit must be bled before testing work and after it is opened
Chapter
Ambient temperature switch
F38
Location: On tow ring bracket, front right.
Only in vehicles with TDI engines.
Switch position -On- at temperatures lower than 5°C.
Switch position -Off- at temperatures above 5°C.
Check the switch states with
vehicle diagnosis, testing and information system
VAS 5051A
; Read measuring value block 08
Chapter
.
Thermal switch
701 959 625
part number.
Removal
Chapter
.
Checking
Chapter
.
Metering pump
V54
Location: In front of the fuel tank, left.
Checking the fuel supply to auxiliary coolant heater B4W or D4W
Chapter
.
It is possible that
metering pump
V54
ticks audibly but still does not deliver fuel because there is air in the intake.
Heater control unit
J162
will then switch off permanently. You should therefore interrogate the fault memory
Chapter
. Erase the fault memory
Chapter
and switch heating B4W/D4W on several times.
Removing and installing
Fig.
.
Check quantity of fuel delivered
Chapter
.
Pre-selection clock
E111
Removal
Chapter
.
Exhaust system
Location: In front left wheel housing.
Removing and installing
Chapter
.
Securing exhaust pipe to heater unit
Chapter
.
Heater unit B4W/D4W
With
heater control unit
J162
.
Location: In engine compartment, left.
Removing and installing
Chapter
.
Dismantling and assembling
Chapter
.
Coolant hoses
Coolant hose routing; connecting the water heater to the coolant circuit
Chapter
.
Circulation pump
V55
Location: Below radiator, front left.
Removal
Chapter
.
Manufacturer's plate for petrol
“B4W”
Note
The most important technical data are shown on upper part of manufacturer's plate.
The date of first use is entered on the lower part of manufacturer's plate.
The year the unit was first put into use must be entered on the
“Genuine spare part”
manufacturer's plate. The heat exchanger of the coolant heaters must not be renewed after 10 years. Legislation in Germany dictates only that air heaters must be renewed.
The manufacturer's plate must be attached at a clearly visible location.
Manufacturer's plate for diesel
“D4W”
Note
The most important technical data are shown on upper part of manufacturer's plate.
The date of first use is entered on the lower part of manufacturer's plate.
The year the unit was first put into use must be entered on the
“Genuine spare part”
manufacturer's plate. The heat exchanger of the coolant heaters must not be renewed after 10 years. Legislation in Germany dictates only that air heaters must be renewed.
The manufacturer's plate must be attached at a clearly visible location.