Webasto Heater Metering Pump Data

Hello.

As described, I am having problems with my Termo TopC. Since it won't start and I have checked everything I can think of, the only thing left is the dosing pump. Would someone be so kind as to measure the internal resistance of their dosing pump (simply disconnect the plug from the burner and measure with a multimeter). This would be very helpful to me.
If anyone has more detailed information about the pump, that would also be very helpful.

Best regards,
Jan.

While I can't provide you with the data from the dosing pump, I can give you a tip on how to check its functionality.

The dosing pump is essentially a simple solenoid with a valve. When you apply 12V to the dosing pump, the solenoid activates, causing a stroke that dispenses a defined (and unknown to me) amount of fuel. When the voltage is removed, the solenoid retracts, but the valve prevents the fuel from flowing back.

If you now alternately turn the voltage on and off, you should see fuel flowing from the line. To test this, you could use the 'Ulf's trick' and connect it to the turn signal.

Regards,
Private.

Oh, guys...

Just give Webasto a call, they're not that scary.

CU Gremlin.

edit: I'd like to measure the Webasto, but you can't access it without a disconnecting switch in less than 2 hours... plus, it's cold outside.

Approximately 5 ohms at the pump of the Thermo Top E.

Yep.

I also measured approximately 5 ohms on my old dosing pump, which is a Thermo Top C.

Regards,
Alfajunkie.

"Thanks a lot for your help. I didn't even realize you had measured anything. The pump itself is working; I've already tried the 'private area' method. The resistance value is also correct. So, there must be another error. I've now ordered a CD with diagnostic software. Hopefully, that will help me find the problem."

@Gremlin:
Yes, they certainly won't bite , but for me, it will cause my underwear to show. I don't live in Germany, and apparently, their hotline costs 12 cents per minute, which easily becomes 50 cents per minute from abroad. There's no hotline here in Denmark (they could only give me the price for such a pump with great difficulty).

Best regards,
Jan.

They also provide information via email or by phone.

CU Gremlin.

Hi.

I just wanted to let you know that I've solved my problems. Thank you for your help.
The error was a poor connection of the glow plug connector. Since the glow plug is also used as a flame sensor by measuring its resistance, the control unit immediately went into emergency cooling mode upon startup due to overheating (caused by the higher resistance value) and then shut down.

The solution turned out to be a CD with Webasto's diagnostic software (available on eBay for 16 euros). I can highly recommend it. The Windows version runs quite stably and is very clear and very easy to use. It allows you to read things like operating hours and, of course, access all system components individually. When you start the heater, you can see exactly what happens and in what order. It works great with a self-built VAG diagnostic adapter (K-Line) and is also significantly more stable than with the EDC .

/Jan