Club 80-90 Forums

Hi folks.
I have a very long-running back project to install a Webasto Thermo Top T BW50 (taken from a T3 Multivan I believe) into my 1986 syncro, as I find the parts.
The bus is now undergoing restoration so I realized that I need to hurry this job along!

A while back I aquired the heater with what looks like most of the tail end loom attached, then later on a NOS 251 963 343A controller from Serial Kombi.
Question is, what else do I need?
Have I got mismatched parts?
Thanks in advance,
Ian

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PS
I am bit concerned that ETKA shows an ECU for the Webasto BBW46, which I do not possess. Those are heavy money from Classic parts!
Some suspiciously clean looking loom plugs here.
I also have the Webasto fusebox and relay.

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I don't work on the water heaters but....
Can't pin down exactly what you have there - id plate shows BW50 yet you say BW46. If it is a BW50 isn't the ecu part of the top of the heater? (under the 4 Philips screwed down area/ID plate )
I have a 12v SG1560 ecu which should be for the BW46 but the white plugs that you show have an extra pair of terminals - one of the plugs is 6 pin (power side) and the other 8 pin on the SG1560. Have you got a loom from a BW46 for a BW50 heater?
That timer may work - depends upon exactly which model you have - OK for BW46! Some may well be W-bus activated if BW50.I may have one of them amongst the odds and ends if needed.

(Very dodgy earth on the fuse block )

Thanks Rick. Yes its a BW50, the wiring all came with it. I havent investigated further tbh.
I wanted to plumb this into the aux heater circuit, with restrictors in the hoses to favour cabin heating over engine coolant but allow for expansion, but this may not be possible.
I realize that I will need some sort of thermostatic device to prevent it overheating if I try to go down that route.
Yes the power supply and earthing is awful!

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One of the plugs may well be for a Telestart connection.

Has anyone got a wiring diagram for a thermotop T BW50?
I've had a hunt around online but can't pin one down.
If someone's got one we should be able to work out what connections Silverbullet needs.

It probably needs at least-
2 power wires.
2 pump wires.
1 or 2 for on/off.
and possibly-
2 for a fuel solenoid.
2 for winter/summer switch.
2 for temperature control knob.
2 for an electric coolant pump.
Hopefully no can-bus.

Is there a part number on that timer Silverbullet?
If we can find a wiring diagram for that too we should be able to match up the wiring between the two.

The timer is for bbw46 - relay type. bw50 uses w-bus not can-bus. Wiring for that is no problem.
I have plenty of manuals but the looms tend to be custom made for the vehicle for the water heaters so need to know the vehicle it came from for certain ( supposed to be T3 in this case but it was the bw46 that was fitted as standard to the T3) to know which manual is required. eg I have manuals for Mitsubishi Space Gear/L400 models.
No temperature control usually on these water heaters as they weren't designed as stand alone heaters.

Thanks again. More info:
I untangled the loom and its got a 02.02.01 manufacturing date, made by Delphi and "DEV:N6149"
This BW50 is 1994, so the loom may be unrelated?
Pics of tail coming off the unit, only 4 wires and the relay/fuse board has the same, plus a couple of skinny ones, red and brown.
Looking a lot simpler now, reckon it might be workable once I have the relevant wiring diagrams for the controller and the heater.
I might need the VW "green knob" cabin thermostat to suit the controller though?

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Ignore that controller that you have there - you need a W-bus one.
Send me your email address and I will get the correct manual off to you. (German only )

Ok. Think I had better try and test this BW50 first. If its dead I will unload the controller or explore another option.

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Once you've simplified the wiring, your timer should function as an on off switch. Your heater will self regulate to some extent anyway. I fitted a DBW46 to mine and used a pipe connector that came with it. It' a sort of double T with a bleed through, that diverts the coolant from the hot feed pipe to your matrix through the webasto and back to the same pipe. if you connect something similar up close to the rear matrix it might give you what you want in terms of priority. You will need some means of activating the fan when used on timer. I think there may be an output from the timer that can activate a relay. It's a long time since I fitted mine and have to revisit it at some point, so my memory is a little sketchy.

That is precisely what I was trying to achieve. Controller simply switches on the heater and likewise a relay for the aux fan.

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silverbullet wrote:Ok. Think I had better try and test this BW50 first. If its dead I will unload the controller or explore another option.

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You won't get it to work with that controller/timer anyway - as I keep saying you need a W-bus one ( see the manual )

Ok ok I get the message!

Out of interest, with which appliances will that OEM controller work?

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BW 46/ DW 46 and most of the earlier than BW50 water heaters.
Thermo Top 90, but not Thermo Top E, C, Z - these are W-bus as are any ST models.
Thermo Top BW 80/ DW80, BW/DW 160,230, BW 2020/DW 2020, BW 300/DW 300, possibly BW 350/DW 350.
Possibly the gas models NGW 300, LGW 300, GBW 300 - not certain about these but not many of these to be seen in the wild.
Possibly DBW 2010/ 2016/ 2020 / 2022 models. + DBW 2010 / 2012 Sensoric models.

You will need to trace the wiring from the ecu on the heater as on old heaters and oem fitments the wiring isn't always true colours to that on the standard wiring diagram. Pin 1 on the 6 pin plug ( x14) on the ecu is the W-bus signal connection which may well be the single connector that you have on the loom ( wiring diagram says black). All the connectors are clean because they were all situated inside the original vehicle ( they are on the inside of the rubber boot/grommet).
The first thing that I do with a heater is strip it and examine motor/combustion chamber and replace as required before I go any further and even attempt to decipher someone else's bodged wiring. I usually then make up a new loom to suit the heater as so many have bad connections all over the place.
You need one of these W-bus controllers: