Repairing BBW 46/DBW 46 water heater — VW

The Webasto auxiliary warm water heater is available as an optional extra (M 975) on Transporter syncro vehicles.

Switch for evaporator blower (E111)

1 -
Set buttons for preselecting heater switch-on time
2 -
Set buttons for preselecting heater switch-on time
3 -
Button for displaying time
4 -
Button for instant heating
5 -
Heater warning lamp, green (K11)
6 -
Time adjuster button, forward
7 -
Display panel (illuminated with L56)
8 -
Code numbers for two selectable times of buttons 1 and 2
9 -
Time adjuster button, back
10 -
"In readiness" warning lamp (yellow)

Display of set time

When the button -3- is depressed, the time is displayed on the illuminated display panel -7- until such times as the button -3- is released.

When the button -3- is released:

the time display disappears completely,
or, if a preselected time has been set, this appears for 2 secs.

Setting the time

If 8:88 flashes in the display panel -7- or the time indicated is not correct, the time can be set by pressing button -3- and one of the two adjuster buttons -6- or -9- simultaneously.

Switching the heater on and off (instant heating)

By depressing button -4- the heater can be switched on or off at any time. The heater starts up when the coolant temperature is below 80° C and the heat control lever is against the stop on the right-hand side. When the heater is switched on, this is indicated by a green lamp -5-. If the heater is not switched off earlier, the heating period is limited to 30 minutes.

Preselecting heater switch-on time

By depressing buttons -1- and -2- a start-up time can be preselected within 24 hours.
The heating period is limited to 30 minutes.

Setting the preselected time

Lightly touch button -1- or -2-.

the previously preselected time appears together with code number 1 or 2 on the display panel -7-.
the yellow "in readiness" warning lamp -10- lights up.
the previously indicated preselected time can be altered to the new time required for heater start-up by depressing the reverse -9- of forward -6- buttons.
after 20 secs. preselected time indication disappears but the code number 1 or 2 on the display panel -7- remains switched on.
the preselected time is now activated.
a prerequisite to ensure that the heater starts up at the time required is that the heat control lever is against the right-hand stop and the fresh air blower is switched on to stage 1.

Cancelling the preselected time

By lightly tapping the -1- or -2- buttons the preselected time (activation indicated by the preselected time shown on display panel -7-) can be cancelled.

the yellow "in readiness" warning lamp -10- and the code letter 1 or 2 on the display panel -7- also go out.