Sprinter Adventure Van Build – Heater Install Part 2 (High Altitude Kit)

After experiencing some issues with our Espar /Eberspaecher D2 sprinter heater when camping in the cold at high altitude (aka, the time you really want your heater to work), we decided to add the high altitude kit to our Espar heater. Like the heater itself, we ordered it from HeatSo.com. And again shipping was fast and the price was good.

The altitude kit is really pretty simple. Its just a little box that you insert in-between the heater wiring and your heater controller (in our case, the EasyStart Timer). So it goes like this…

Original Wiring/Device Order:

Custom Text

Heater Wiring –> <10 pin connector> <– EasyStart Timer Controller

New Wiring/Device Order:

Heater Wiring –> <4 pin connector> <– High Altitude Sensor –> <10 pin connector> <– EasyStart Timer Controller

Detailed Wiring Diagram (PDF)

Wiring the high altitude kit is also pretty easy, presuming you are doing it this way for the first time. IF you are like us and retrofitting the high altitude kit, it is a much bigger pain (read: just get the high altitude kit the first time and avoid this problem). The issue is with the connectors, they are pretty easy to assembly, crimping the wires into the pins and then sliding the pins into the plastic housing. The problem is, you cant get those pins out again. Like really, not possible – I tried for about an hour and ended up destroying the plastic housing / harness.

Fortunately, if you are reading this and going through this nightmare, I have already figured it out for you. You just need to order a new molex type connector and pins. I got mine from Digikey for under $10 (but requiring about 2 hours of research to find the right part). The part numbers are WM4772-ND for the connector and WM3112CT-ND for the pins. Once you have those parts its easy. Just cut off the old connector and wire in the new one on the other side of the High Altitude Sensor.

Since the circuit diagrams from Espar / Eberspacher are hard to read (at least I don’t find them very straightforward) I put together my own wiring diagram to help me clarify things. Hopefully this is helpful to you.

Note: I had the yellow wire connected through the high altitude sensor initially, this appears to be incorrect. The heater was working, but I was getting occasional ‘no signal’ errors. Will report back once this new wiring has been tested out more significantly. However, per the wiring diagram to the right, DO NOT CONNECT THE YELLOW WIRE.

Note 2: I don’t think the yellow wire had anything to do with the ‘no signal’ errors. But it is still not necessary to attach this.The ‘no signal’ problem kept on being an issue and was finally rectified by replacing the EasyStart Timer with a regular EasyStart controller. It was a long and winding road to get to that conclusion which you can read about here.

7 thoughts on “Sprinter Adventure Van Build – Heater Install Part 2 (High Altitude Kit)

  • Logan Wealing


    Thanks the for great blog. Did you ever get rid of the “NO SIGNAL” error on the Eberspacher? I also have an Eberspacher (Hydronic II) heater with a high altitude kit and Easystart Timer. No matter what I do I still get the “NO SIGNAL” error. Even tried your suggestion of disconnecting the yellow wire without luck. Any suggestions would be appreciated.

    • I’m still fighting the no signal error. The hard part is that it is so random when it comes around (at least it seems random). It will work fine, running for days and then randomly no-signal will still appear. When it happens, basically everything is tuck – and it says that I don’t have diagnostics, even though the EasyStart Timer (EST) is a diagnostic instrument, itself. I have redone all my connections to remove any kind of wiring issue. My latest thinking is that it’s the altitude kit – not from any scientific reason, just because its either that or the EST. So right now I am running without altitude kit – problem hasn’t shown up yet – but then, it probably wont until I least expect it.

      I have a thread here that’s been documenting the various trials. Feel free to jump on that and add your experience. Would love to figure this out.


  • Thanks for the details on connector parts. I couldn’t believe that Heatso didn’t include an extra connector or two in the complete install kit for my D2 heater. I mangled one on the dosing pump wiring and had to solder it. Spent an afternoon driving around trying to find same connector. I didn’t buy high altitude kit from start and going to add it now. Glad I found your blog.

  • It looks like you have the Easy Start Timer fitted to a faceplate that will sit in that little cubby (sunglass holder) space above the map light between the driver and passenger visors. Where did you get the matching gray plastic face plate?

    I have a 2016 Sprinter 144 4×4 to compare. Thanks for these tips!! We ordered the High Altitude sensor right out of the gate because of your recommendation.

    • Patty – awesome! We’ll have to compare notes on how everything works. The “faceplate” came with our van. I believe the compartment we put our altitude sensor in was for a CB radio (has power in there too) and the faceplate cover is removable. Not sure where you could get it, or something like it. Looking into it a bit more, it appears this is part of the FF8 Option “Storage Slot at Front U/ Roof Liner”. But if yours didn’t come with that, you might be able to cut something out of plastic or wood that works the same?

  • Another Sprinter Owner

    Sorry you had to go through all that! But thank you for sharing the connector type and confirming that I made the right decision by getting the high altitude kit with my initial purchase.


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