Coolant heater?

[sidepod]

So mine doesn’t appear to be working !

I don’t do “not working”.

Before I start digging, anyone know of any common issues, fuses etc that cause issues?

What temp should it kick in?
-2 outside at the moment.

Ta v much.

P.

 

[bxl_lad]

I always understood it kicked in below 5 degrees...

 

[sidepod]

I was in it yesterday and I noticed the outside temp display wasn’t showing a reading. Probably the two faults are one and the same.

Do you know where the temp sensor unit is? Front bumper area?

 

[Hotel California]

This always help to search for parts and locations.
The link is T5 related but you can change the verhicle details
http://www.oemepc.com/vw/main_group...tgruppen/1234567890/drive_standart/733/lang/e

 

[bxl_lad]

Sensor on mine is near the number plate. The first connection for it is behind the left side of the bumper (spotted all this when doing the fog lamps recently)...
Not sure if there is a fuse circuit for it?

 

[mrcheesbrough]

I was in it yesterday and I noticed the outside temp display wasn’t showing a reading. Probably the two faults are one and the same.

Do you know where the temp sensor unit is? Front bumper area?

The sensor you’re after is behind the bumper near the horn. Left hand side when you’re stood looking at the bonnet. The sensor maybe at fault, you can ‘jump’ it with a short piece of wire. Next thing is the A+ feed (thin blue wire I believe) that goes to the heater. If that’s broken the heater won’t fire. If it’s going to fire it’ll only do it with the engine running.


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[sidepod]

Thanks Mr C. Where did you get the wiring info from? A+ wire ?

I found this. D5WZ?

I believe the b wire is the temp sensor (behind bumper)

 

[mrcheesbrough]

Thanks Mr C. Where did you get the wiring info from? A+ wire ?

I found this. D5WZ?

I believe the b wire is the temp sensor (behind bumper)

View attachment 31125

Sorry. May of got my colours wrong. This is an extract from the PDF I found while trawling the internet to diagnose ours.

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[sidepod]

Or is it a Thermo Top C?

 

[mrcheesbrough]

Or is it a Thermo Top C?

Eberspacher D3WZ. Have a look at this https://www.butlertechnik.com/downloads/Eberspacher_D3WZ_Hydronic_heater_workshop_manual.pdf much more detailed.


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[MattBW]

Have more than a quarter tank of fuel? I know that on my t5 once you get below a quarter it doesnt kick in.

 

[sidepod]

New temp sender unit on it way.

I’m confident this is the issue.

Update to follow.

 

[mrcheesbrough]

New temp sender unit on it way.

I’m confident this is the issue.

Update to follow.

Did you jump the temp sensor connector with a piece of wire? The heater should fire then when you start the engine. Regardless of the external temperature.


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[sidepod]

Easy tiger. I’ll try tonight when I get home.

I was toying with the idea of a switch in parallel with the sensor then I could opt to use it on days when it’s not quite 5 deg. ?

 

[mrcheesbrough]

Easy tiger. I’ll try tonight when I get home.

I was toying with the idea of a switch in parallel with the sensor then I could opt to use it on days when it’s not quite 5 deg. ?

Raaaaar! It’s just a quick way to eliminate the temp sensor. I’ve decided to do this in the summer just to give the heater a run as it’s pretty rare the temp drops low enough in this country. At least that was before all this global warming kicked off. You buying from VW? C’est combien? I don’t think ours is entirely accurate.


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[sidepod]

Ok update.

I pulled the sensor out and shorted out the socket. Sadly nothing.

I assume the heater fires up after a few minutes?

I did put a meter across the contacts of the sensor - open circuit. I didn’t measure the resistance.

So perhaps it’s not the sensor after all?

I can find any wiring diagrams that show the interface with the rest of the van.

It would be good to see the whole scheme.

New sensor from VW, £30 ish. Gulp.

 

[mrcheesbrough]

Ok update.

I pulled the sensor out and shorted out the socket. Sadly nothing.

I assume the heater fires up after a few minutes?

I did put a meter across the contacts of the sensor - open circuit. I didn’t measure the resistance.

So perhaps it’s not the sensor after all?

I can find any wiring diagrams that show the interface with the rest of the van.

It would be good to see the whole scheme.

New sensor from VW, £30 ish. Gulp.

Yeah. It doesn’t take long for the heater to fire. I think it should take around 90s to perform all the self checks and be fired up.

From reading around (pulling info from multiple places on t’internet) there’s very little interface with the van. The temp sensor determines whether it should fire, the D+ feed from the Alternator lets the heaters built in ECU know the engine is running. The heaters fuel pump feeds from the fuel tank and is controlled by the heaters ECU. As far as I can make out the D3WZ doesn’t have a permanent lockout due to any faults. It just self checks each time it’s required and decides then whether it’s fit to fire. You may want to check the Glowplug resistance, it seems to be the most common cause for it not firing. However this will require a partial dismantling of the heater to access the internal wiring.

All good fun if you’ve the time and no immediate need for the camper to be roadworthy. Bypassing the water circuit temporarily isn’t a simple task.


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[sidepod]

Is there a fuse?

 

[sidepod]

F17. 10A?

 

[sidepod]

Useful

 

[mrcheesbrough]

Useful

Interesting. Maybe not that useful in diagnosing the fault your heater may have. Essentially the heater is pretty much self-contained, relying on the vehicle for a fuel supply and an external temperature measurement. The final note about the glowplug is certainly useful. Checking this will require removal of the heater. Not a difficult job, just a fiddle.


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[sidepod]

Thanks Mr C. Good intel.

Given that it was about -50 outside last night I didn’t spend time to check the temp sensor actually had a supply to it! Brain clearly not functioning.

It wouldn’t surprise me if it was dead. The previous owner carried out a lot of wiring mods, conceptually good but the execution appalling. I’ve been steadily re-doing it properly.

I can’t see the temp sensor being faulty now I think about it, it’s only a resistor after all.

More poking about tonight.

 

[burnercan]

Useful

Quite, good find.

Seems the 1/4 tank of fuel requirement that was mentioned earlier is not applicable to these heaters, based on the wire pinout the video explained. Would the min fuel level parameter be only for the parking heater?

 

[sidepod]

Quite, good find.

Seems the 1/4 tank of fuel requirement that was mentioned earlier is not applicable to these heaters, based on the wire pinout the video explained. Would the min fuel level parameter be only for the parking heater?

I’d agree. The parking heater could conceivably empty the tank where as the coolant heater is switch off via the thermostat in the coolant loop.

 

[sidepod]

So here’s part of the jigsaw.
From the connectors on the rear of the fuse box (A2 and D) one should be able to line check to the connector at the heater.

This shows the D+ line from the alternator which is the permission to run signal.