Webasto wiring!

[JAY1]

Evening all!

Just picked up a webasto air top 5000 to replace my eber d1lc which was far too small for the job!

I bought it used from an ambulance breakers so it naturally included a butchered wiring loom.

I have managed to fathom most of it and wire it up but have one 2-pin connection left over (Which I assume is for the external temp sensor) however, I am also left with a single purple wire and a single red wire which have both clearly been cut but I cannot see what they should connect to. (already have the power feed connected up).

Tried to power up and the led light turns on on the controller and the fan powers up ever so slightly (perhaps a split second) and then stops and nothing more happens. Anyone able to help? Have tried searching for a wiring loom diagram but cannot find one anywhere!

All help much appreciated.

Many thanks
Jay

 

[rob2]

I found this on-line manual which shows a sort of wiring schematic, though I can't find a purple wire!

http://techwebasto.com/redirect/heater_main/5001186A.pdf

Rob.

 

[pvb]

There are more wiring diagrams in the workshop manual, including some with violet wire - http://butlertechnik.com/download/78/webasto_air_top_5000_workshop_manual.pdf

 

[David2452]

Purple and violet is normally used in ADR and not of any interest or use to you, the red cable may well be for ignition sense which in ambulances ensures the heater shuts down if the vehicle is turned off. However if you trace it back to the pin number on the 12 pin ECU plug I will be able to tell you for sure. Colours can be misleading as some OEM harneses differ so the pin assignment is the surest method. It is unusual for an old AT5 to have provision to have an external temp sensor, what colour are the two cables, and is there an internal sensor plugged in to the left of the main 12 pin ECU plug? By the way as you have swapped out a D1 I assume you are upgrading the duct size too otherwise you risk overheat shutdowns. Also be aware that ambulance ECUs are at the upper end of cut out voltage so make sure your batteries are well charged and you use decent size supply cable.

 

[JAY1]

Thanks for the fantastic replies guys!

I have looked at the wiring diagrams and unfortunately can't make sense of them...

The heater was connected to my port battery and then i hooked it up to an independent battery charger which has a 'constant power' setting of 13.8v but the problem persisted on either setup. I linked up to the original battery feed which had much thicker cable than the harness for the webasto so would assume no problems there.

I am not at the boat today but I know I don't have a sensor plugged in next to the wiring harness and there didn't seem to be any provisions for it. I will check the connector hopefully tomorrow and get back to you.

The original d1lc only had two outlets with 60mm ducting, I am adding a third outlet into the wheel house using 90mm ducting and then planned to put a reducer and link up to the original 60mm ducting. Would this cause problems?

Thanks agin for all the great responeses!

Jay

 

[David2452]

Firstly, no problem with the reduction in duct with the first duct and vent being 90mm, the vent should be non closable. There must be either an internal sensor, plug with leads for an external sensor or an empty space to the left of the horseshoe ECU 12 pin plug, can't be any other way (see page 701 of the workshop manual) Assuming the heater is OK then all the wiring needed is + to pin 4, - to pin 5. Control rheostat should be blue to pin 8 and white to pin 11, it will expect varying resistance or open circuit there. In the rheostat switch is the LED indicator which will be red to pin 2 and black to pin 6, that's it. Of course there are also many other control systems and OEM ECU variants which expect input from the vehicle and the last sentence of your OP describing the brief lighting of the LED and short fan spin could easily be an ECU fault or vehicle specific ECU expecting other information. I have had exactly the same symptoms when people have bought ex VW T5 units which have a special ECU and will not work out of the van without a new ECU or some jiggery and a smart controller, all of which cost more than they paid for the heater.

 

[JAY1]

Popped to the boy last night. There is a connector with nothing plugged into it on the wiring loom. It has one Green and one brown cable running from pin 10 and 9.
+ and - are connected correctly as per above reply.

The led light stays on for as long as I leave the thermostat turned on if that makes any difference?
Then I am left with a red and violet wire - I did attempt connecting the power to the red cable but still had the same symptoms of the fan tuning for a split second and then stopping.

I guess it's looking more like a dud.....

 

[David2452]

The green (actually green with white tracer) on pin 10 is the Thermotest diagnostic connection, the brown cable on pin 9 is the grounding cable for use during burn efficiency CO2 setting, usually on the same plug, so nothing to do with normal operation.
Your latest description of the light remaining on is indicitive of the thing thinking it is at temperature already so does not spark up as well as the duff or inapropriate ECU issue I aluded to earlier. If you want to box it up and send it to me or bring it along I would pop it on the test bench with Thermotest FOC and confirm any faults for you. Obviously that's all i could do at no cost though.
I do have a couple of known good used AT 5k ECUs

 

[JAY1]

That's a really kind offer David. Where are you based?

Thanks,

Jay

 

[David2452]

That's a really kind offer David. Where are you based?

Thanks,

Jay

My office & workshop is in South dock Marina.

 

[JAY1]

I know exactly where that is as I used to live on Rope Street!
Is the Wibbly Wobbly still going?

Would it be ok to pop down sometime during the week?

 

[David2452]

I know exactly where that is as I used to live on Rope Street!
Is the Wibbly Wobbly still going?

Would it be ok to pop down sometime during the week?

No, it's been condemned unsafe sadly. I will be around the marina this week but you will need to confirm the day before and the earlier the better from 06:00. I will PM you my mobile & email address.