retrofit auxiliary/parking heater to camper van which has no oem heater installed

[rippelep]

Hello, one of my dreams is to admire the Northern Lights in the north of Europe live, and that with my campervan T6 Transporter 2017 110kw dsg with climatic, which unfortunately has neither auxiliary heater nor water parking heater installed from factory. The first goal of my project is to make it easier for the vehicle to start at very low temperatures. If the heater in the front is warm for driving, that's fine too. I have already installed an air heater, so standing/sleeping/camping in cold environment is no problem. The aim is therefore to retrofit the auxiliary heater and parking heater functionality as close as possible to the original model.
In the meantime, I have ordered cheap used parts from a 2018 T6 transporter with which I can experiment, one directly a parking heater with complete wiring harness and brackets (and I hope with the OEM Software):


and the associated control unit, both from the same vehicle:


A remote control is not necessary for now, because I will live in the vehicle during the intended use and can then operate directly.
Is it even possible to achieve full OEM functionality as auxiliary heaters and parking heaters with home remedies?
Topics include:
provide all the cables that the heating control unit needs accordingly from a car that has no heater installed.
Control of the blower, climatics and at the end the programming of the control units.
I have no problem with creating wiring harnesses, finding and tapping bus lines, etc., I've already done that when retrofitting the multifunction steering wheel and a bus-controlled alarm system. VCDS is available.
I'm just familiarizing myself with the circuit diagrams.

Of course there are a lot of useful information in the threads about retrofit aux heater to parking heater, I read and learned a lot of them, but I have to start somewhat from scratch....
If someone has already done something like this, that would be great, any information would be helpful...
Greetings rippelep

 

[mmi]

complete wiring harness

You got the pumps, too?
The wiring diagram might still be useful...

Auxiliary Coolant Heater Wiring Diagram

12 Jul 2021

Current flow diagrams

• Pauly
• auxiliary heater coolant heater
• VW T6 Electrical Info

as well as for general information

SSP 415 - Supplementary Heaters - Part 1

1 Oct 2022

VW Self Study Program

• Pauly
• VW T6 Vehicle Information

Also useful is Workshop Manual - Transporter 2016> - Auxiliary heater
Either from
Volkswagen AG erWin Online
or a cheap/cheeky copy at Скачивание файла -vw-t6-auxiliary-heater-eng.pdf

 

[rippelep]

pumps? yes, for water and fuel, if you mean those....or are there others?

 

[rippelep]

So, I'm a bit lost with the wiring, hardware is no problem, device disassembled, everything looks good, and everything around it cleaned.

But the wiring makes me crazy, just as an example the control of the V55 pump:

This has two contacts that are not controlled by the heater itself, which must be controlled via the T17p/11 relay. There are several relays in the vehicle (with auxiliary heater) in play, all of which are unfortunately not available in my vehicle.

First J496 Additional coolant pump relay, which is then connected via the relay J708 (Residual heat relay) to the V55 pump as standard. The relay can then also switch the pump via J301 Air conditioning system control unit (Climatic) (that is my understanding of the wiring, might of course be wrong).


What is meant by the Additional coolant pump? Is it the V55 pump, which is then controlled in a cascade via two relays. Or another pump, with which the V55 is then normally synchronized, so to speak, but can also be switched via J301? There are some electric pumps in the cooling circuit, e.g. V488, it would make sense to let the V55 run when V488 is running (for example in the warm up time), since the V55 is looped into the heating circuit and thus possibly would even slow down or stop the flow if not running in that situation:


But, according to the documentation, V488 is controlled by a PWM signal, so no relay is actually necessary?.

Or can a PWM signal switch a relay?

If I look for a wiring diagram for J496:


I wouldn't know how I could switch the relay (165??)

Many questions...

Or I would have to go an alternative (not exactly OEM) way, e.g. if the Webasto is started via the bus, see if there is a signal/voltage on one of the cables of the Webasto and then control the pump via a relay.

And this is just the first problem I see, similar things with the relay J8 and J493.
I am afraid not just the relays are missing in my car, but also some other cables, fuses….
I believe I have to rethink this project.
So if anyone has an idea.....

And sorry for showing things in german, I did not find the english version for that, and all the other mess

 

[rippelep]

Next steps:
Collected all parts needed for hardware installation:


and in the car:






Preparing the wiring:


Next step: installing the wiring in the car, waiting for the rain stopping.....

 

[rippelep]

next step, maybe the last
all installed in proof of concept state, not final,
metering pump is running, so filled the line up to the heater with vcds
coded with vcds,
state now from software:
-------------------------------------------------------------------------------

Address 18: Aux. Heat (J364) Labels:| 7E0-963-27X-18.clb
Part No SW: 7E0 963 272 B HW: 7E0 963 272 B
Component: STH-T5GP2 003 0009
Coding: 4101
Shop #: WSC 20342 002 104857
ASAM Dataset: EV_AuxilParkiHeateWOST5G2 001013
ROD: EV_AuxilParkiHeateWOST5G2.rod
VCID: 2B0200D4038C4DE20B1-807E
1 Fault Found:
0376 - No Basic Setting
B2010 00 [00001001] - -
[INITIAL OPERATION MISSING]
Confirmed - Tested Since Memory Clear
Freeze Frame:
Fault Priority: 6
Fault Frequency: 1
Reset counter: 105
Mileage: 190419 km
Date: 2025.10.30.
Time: 09:52:37
Parking heater: operating condition: OFF
71
Coolant temperature of parking heater: 9 °C
Coolant temperature: 9 °C
Engine running status: not detected
Fuel level: 71 l
Heating performance: 0 W

That is the state I always get if I remove all errors from the heater, this error will apear directly again.

And for the roof display:
Address 6E: Ctrl Head Roof (J702) Labels:. 7E5-919-037-W2.clb
Part No SW: 7E5 919 037 J HW: 7E5 919 037 J
Component: Dachdisplay H17 0200
Revision: 1010013S Serial number: 521544
Coding: 000102
Shop #: WSC 02759 790 00000
VCID: 38282F98C25AF67A763-806C
1 Fault Found:
01207 - Control Module for Auxiliary Heater (J364)
008 - Implausible Signal
Freeze Frame:
Fault Status: 01111000
Fault Priority: 3
Fault Frequency: 2
Reset counter: 105
Mileage: 190419 km
Time Indication: 0
Date: 2025.10.29
Time: 15:14:37

that error can be deleted permanentely

next:
as I said, Metering pump works,
recirc. pump, relay clicks, but does not work physically, I disassambled it, it runs or runs not dependend from the pumps rotor state. If I move it a little bit it sometimes starts (or not), but that is a problem I can solve (a new pump)
but:

result:

->
VCDS Version: Release 25.3.2 (x64) Running on Windows 11 x64
www.Ross-Tech.com
Address 18: Aux. Heat Labels: 7E0-963-27X-18.clb
Control Module Part Number: 7E0 963 272 B HW: 7E0 963 272 B
Component and/or Version: STH-T5GP2 003 0009
Software Coding: 4101
Work Shop Code: WSC 20342 002 104857
ASAM Dataset: EV_AuxilParkiHeateWOST5G2 001013 (VN75)
ROD: EV_AuxilParkiHeateWOST5G2.rod
VCID: 2B0200D4038C4DE20B1-807E
2 Faults Found:
0021 - Combustion Air Blower
B1384 07 [00001001] - Mechanical Failure
Confirmed - Tested Since Memory Clear
Freeze Frame:
Fault Priority: 3
Fault Frequency: 1
Reset counter: 105
Mileage: 190419 km
Date: 2025.10.30.
Time: 10:00:49
Parking heater: operating condition: System malfunction
71
Coolant temperature of parking heater: 9 °C
Coolant temperature: 9 °C
Engine running status: not detected
Fuel level: 71 l
Heating performance: 0 W
0376 - No Basic Setting
B2010 00 [00001001] - -
[INITIAL OPERATION MISSING]
Confirmed - Tested Since Memory Clear
Freeze Frame:
Fault Priority: 6
Fault Frequency: 1
Reset counter: 105
Mileage: 190419 km
Date: 2025.10.30.
Time: 09:59:41
Parking heater: operating condition: OFF
71
Coolant temperature of parking heater: 9 °C
Coolant temperature: 9 °C
Engine running status: not detecte
Fuel level: 71 l
Heating performance: 0 W

errors cleared
then:

result:


errors cleared.
then:

I can hear the coolant pump relay clicking on.

relay off click.
again:
Heater:
Thursday,30,October,2025,09:07:41:38875
VCDS Version: Release 25.3.2 (x64) Running on Windows 11 x64
www.Ross-Tech.com
Address 18: Aux. Heat Labels: 7E0-963-27X-18.CLB
Control Module Part Number: 7E0 963 272 B HW: 7E0 963 272 B
Component and/or Version: STH-T5GP2 003 0009
Software Coding: 4101
Work Shop Code: WSC 20342 002 104857
ASAM Dataset: EV_AuxilParkiHeateWOST5G2 001013 (VN75)
ROD: EV_AuxilParkiHeateWOST5G2.rod
VCID: 2B0200D4038C4DE20B1-807E
3 Faults Found:
0021 - Combustion Air Blower
B1384 07 [00001001] - Mechanical Failure
Confirmed - Tested Since Memory Clear
Freeze Frame:
Fault Priority: 3
Fault Frequency: 1
Reset counter: 105
Mileage: 190419 km
Date: 2025.10.30.
Time: 10:05:00
Parking heater: operating condition: OFF
71
Coolant temperature of parking heater: 9 °C
Coolant temperature: 9 °C
Engine running status: not detected
Fuel level: 71 l
Heating performance: 0 W
0130 - No Flame Detected
B1389 F3 [00001001] - During Test
Confirmed - Tested Since Memory Clear
Freeze Frame:
Fault Priority: 3
Fault Frequency: 1
Reset counter: 105
Mileage: 190419 km
Date: 2025.10.30.
Time: 10:05:00
Parking heater: operating condition: OFF
71
Coolant temperature of parking heater: 9 °C
Coolant temperature: 9 °C
Engine running status: not detected
Fuel level: 71 l
Heating performance: 0 W
0376 - No Basic Setting
B2010 00 [00001001] - -
[INITIAL OPERATION MISSING]
Confirmed - Tested Since Memory Clear
Freeze Frame:
Fault Priority: 6
Fault Frequency: 1
Reset counter: 105
Mileage: 190419 km
Date: 2025.10.30.
Time: 10:02:45
Parking heater: operating condition: System malfunction
71
Coolant temperature of parking heater: 9 °C
Coolant temperature: 9 °C
Engine running status: not detected
Fuel level: 71 l
Heating performance: 0 W

The heaters blower seems to be defective (or something in his context, wiring?)

I than made a blockmap (as mmi always mentions) from 18 and the roof display,

the data are looking not bad, also the glow plug resistance seems normal?
IDE06616-MAS05030,Glow plug with flame monitoring-Resistance,0.272, Ohm

I will disassemble the heater again, checking all wires specially for the blower,
but I have no idea to go on......

blockmap:
blockmap heater

 

[TALLANDREW]

Wow that’s impressive.

 

[rippelep]

many ups and downs in my project
just an example: the water pump I bought did not work. Waited 5 days for a new one (cheap for the proof of concept thing). In the webasto manual is noted: if pump is dropped dont use it anymore. And what happened? It smashed to the ground, causing a very very little damage internally, just if under pressure, which then flooded the electric with water.
So now again waiting for the next pump....

But other things are good, disassembling and cleaning the blower made it work again, its running integrated in the car(with the engine running also to prevent overheating due to the missing pump), after clearing all errors with the webasto testsoftware and VCDS. (but thats just the short story)


For the moment I am working at a solution for all elements powered by by secondary battery, heater, pump and car blower. Looks also good, I got most infos needed from this forum, many thanks for that.

 

[TALLANDREW]

Know your pain, my vans been off the road over a week now and it’s starting to annoy me cycling 25km every other day to work and back in poor weather.

I’m Trying to fit an auxiliary oil cooler to engine.

When I get home I’m too knackered to go in garage and work on the van. So the project is really dragging

 

[rippelep]

Some days later the webasto water heater works as intended!!!
All pumps, blowers and the heater are sourced by the leisure batterie, heater works in auxiliary mode when driving and as a programmable parking heater otherwise.
I can control it via the roof display or remotely via a solution with my renogy ecosystem, I will describe it later.

Here some more pictures:

integration in the cooling system:



hoses:


Under the seat, pump relay retrofit (J708) and telestart:



retrofitted relay J708, provides fused terminal 30 from auxiliary battery when requested via the climate control unit. Since I don't have the relay J496 (residual heat relay), the changeover relay becomes an on/off relay.

oem:
my solution


Fan control,
modified relay J8, now changeover relay
between supply from air conditioning unit when ignition is on and supply from additional battery when ignition is off.

oem solution relay J8 for my car with climatic
.


in the oem solution the power of the output of relay J8 is just added to the source for driving state with ignition on, thats no problem as the source is the same, the starter battery. In my solution, blower is driven by leisure battery, I tried to prevent the two different sources (with different potential, in this case voltage) switched together which might have impact on electronics (e.g. flow back current)
If ignition is on, the leisure batterie source is switched off.
In that case the blower is sourced in normal way via the climatic unit. The signal from the heater is then always inactive also. (if not then the blower stage 2 would just not work due to missing source)


climate unit

 

[oldiebut goodie]

What fuel pump have you used there? It doesn't look like a DP42 looks more like an eberspacher one.

 

[rippelep]

What fuel pump have you used there? It doesn't look like a DP42 looks more like an eberspacher one.

yes, the photo is misleading, thats the pump for the autotherm air heater on the other side. I repositioned it a little bit meanwhile not to be to near at the waterheater. The pump for the waterheater is on the other side at its original position, not visible on the photo, as you can see here:

 

[rippelep]

next,
Diagnostics and basics for remote control with the Telestart
Connector with W-Bus signal for optional temporary control of the Webasto test software via an ODB interface for diagnostic purposes , accessible at any time via a plug under the seat, or otherwise connected to the telestart control modul.



Webasto Testsoftware, was needed to delete all the old errors.


Testing the signal input of the telestart, triggering the heater

 

[rippelep]

next, remote control via renogy one m1

I don't have an original webasto remote control, I use the Renogy system installed in my camper. I have a renogy One m1 display that is connected to my wifi router and then reachable via internet. It can be operated directly in the vehicle or from anywhere via app, if there is an internet connection on both sides. This display has three programmable relays built in (and with switches also). It is also possible to generate only a pulse. This allows me to turn the heating on and off via the signal input of the telestart module, just like my autotherm 2d, directly via the display or via mobile phone from bed in the van, at home or wherever. Theoretically, this could even be automated depending on, for example, the vehicle interior temperature, time, the m1 can integrate sensors via Zigbee protocol, as can be seen in the screenshots (temperature water area, battery, living space)

For example, in winter operation, I can automatically prevent water from freezing in my water compartment or the lithium battery from getting too cold starting the air heater for some time.



scene:
then on the smartphone:

 

[rippelep]

Next:
Problems
What is described all sounds so simple, but in reality it wasn't.
Since I worked with used parts, of course not everything was functional.
The water pump had a crack internally, which flooded the electronics and of course it did not run. I bought a new one, it crashed to the ground, grrr, again internally cracked, so the next one to buy (and wait).
As described at the beginning of the thread, there was also a mechanical fault of the blower. I disassembled the heater twice, including the blower, cleaned everything, installed new seals, tested it.
I worked with the webasto test software and vcds simultaneously, and switched the burner via roof display for initialization, the errors were then always deleted from both sides until everything ran smoothly.
But, In the end, everything went well.

The electrical integration was also a challenge, as I wanted to supply everything with the additional battery and the vehicle had no preparation for the heater (e.g. relays). This required many hours of reading and thinking, not all, but mostly in this forum and material from the download area.

Test of the blower in the kitchen

 

[rippelep]

Next,
VCDS settings

 

[eugene]

Wow! Hats off for so indepth work! Not for the fainthearted!