Eberspacher Control Unit Failed?

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alan_d

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I think that the control unit of my Eberspacher may have given out, but before I splash out £100+ on a new one I would welcome suggestions about other possible diagnoses, or investigations I might usefully try.

My Airtronic D2 was professionally installed about 12 years ago and it has never given me any trouble, although I don't use it a great deal - just a few hours in Spring in Autumn. When I came to try it last September it was completely dead - the 24 hour/7 day control unit being completely unresponsive and looking just as it does when the battery is disconnected - no LCD display. At that time I suspected a blown fuse or a loose connection and resolved to check it out before the start of the new season. I have now spent some time crawling around in lockers tracing the wiring and looking for the in-line fuse that I expected to exist, to no avail. I couldn't find a fuse at all, and indeed I could not work out how the Eber was connected to the boat's 12 volt supply. There is a smart, well-secured Eberspacher wiring loom connecting the control unit, the cabin temperature sensor, the Eber fuel pump and the heater itself, but this seems completely self contained and not to be connected to anything else. I expected that the 12 volt feed would be somewhere close to the control unit, which is right next to the rat's nest of wires behind the main distribution/fuse board, but I couldn't find anything of the kind. I was planning to ask the collected wisdom here where I should be looking for the 12 volt feed, when I did what I should have done at the outset and checked the voltage across the wires leading into the back of the control unit and found healthy battery voltage there. I have therefore now concluded that the problem must lie with the control unit itself, but would would be glad to hear what the team thinks.

Thanks,

Alan
 
Thanks, Harry. While I might follow your advice if I were starting from scratch, or if I had experienced nothing but trouble from the Eber, I am not attracted by the idea of spending £650 on a Mikuni (plus installation) versus hazarding £120 on a new control unit.
 
alan_d said:
Thanks, Harry. While I might follow your advice if I were starting from scratch, or if I had experienced nothing but trouble from the Eber, I am not attracted by the idea of spending £650 on a Mikuni (plus installation) versus hazarding £120 on a new control unit.
Click to expand...
I have repaired many ebers over the years. If your unit has the main ECU lead encapsulated in hard plastic as against wrapped in woven tape then it is the older type ECUs which (alas) were prone to failure. ( I still have several D2s all waiting new ECUs) If your other parts are all good then flog em for spares and put the money towards a 'Chinese' heater.
 
Find out where it gets its power from. Establish with your multimeter that it is actually getting power.
Check the fuse in the unit or on the wiring to it.
Or pay £120 for a new ECU, fit it only to find out that its not the problem, and be really sad.
 
Boater Sam said:
Find out where it gets its power from. Establish with your multimeter that it is actually getting power.
Click to expand...

from post #1

"I should have done at the outset and checked the voltage across the wires leading into the back of the control unit and found healthy battery voltage there. "

Check the fuse in the unit or on the wiring to it.
Click to expand...

From post #1, see above, plus:

"I couldn't find a fuse at all"

Or pay £120 for a new ECU, fit it only to find out that its not the problem, and be really sad.
Click to expand...

An ECU will be several hundreds of ££££s. A controller will be £120 ish, but unlikely to be the problem, almost certainly an ECU issue.

To the OP, if it is the ECU, bin the heater and fit a genuine Planar heater, rather than a cheapo Chinese Eber copy.
 
PaulRainbow said:
from post #1

"I should have done at the outset and checked the voltage across the wires leading into the back of the control unit and found healthy battery voltage there. "



From post #1, see above, plus:

"I couldn't find a fuse at all"



An ECU will be several hundreds of ££££s. A controller will be £120 ish, but unlikely to be the problem, almost certainly an ECU issue.

To the OP, if it is the ECU, bin the heater and fit a genuine Planar heater, rather than a cheapo Chinese Eber copy.
Click to expand...
Sorry when the OP said controller I assumed the 'control unit' alias the ECU ! ( in eber parlance) The 'timer/control switch' can easily be bypassed to check it by connecting the yellow to the red lead. If the OP wants just a control/switch then a used one will set him back £20. I still recommend that if all else fails bin the eber and buy Chinese!
 
pcatterall said:
Sorry when the OP said controller I assumed the 'control unit' alias the ECU ! ( in eber parlance) The 'timer/control switch' can easily be bypassed to check it by connecting the yellow to the red lead. If the OP wants just a control/switch then a used one will set him back £20. I still recommend that if all else fails bin the eber and buy Chinese!
Click to expand...

Hmmm, i'm not sure what he means now Pete. I thought he meant there was power at the ECU/heater, but talk of spending £100 on a replacement sounds more like the timer/switch ?????
 
alan_d said:
I think that the control unit of my Eberspacher may have given out, but before I splash out £100+ on a new one I would welcome suggestions about other possible diagnoses, or investigations I might usefully try.

My Airtronic D2 was professionally installed about 12 years ago and it has never given me any trouble, although I don't use it a great deal - just a few hours in Spring in Autumn. When I came to try it last September it was completely dead - the 24 hour/7 day control unit being completely unresponsive and looking just as it does when the battery is disconnected - no LCD display. At that time I suspected a blown fuse or a loose connection and resolved to check it out before the start of the new season. I have now spent some time crawling around in lockers tracing the wiring and looking for the in-line fuse that I expected to exist, to no avail. I couldn't find a fuse at all, and indeed I could not work out how the Eber was connected to the boat's 12 volt supply. There is a smart, well-secured Eberspacher wiring loom connecting the control unit, the cabin temperature sensor, the Eber fuel pump and the heater itself, but this seems completely self contained and not to be connected to anything else. I expected that the 12 volt feed would be somewhere close to the control unit, which is right next to the rat's nest of wires behind the main distribution/fuse board, but I couldn't find anything of the kind. I was planning to ask the collected wisdom here where I should be looking for the 12 volt feed, when I did what I should have done at the outset and checked the voltage across the wires leading into the back of the control unit and found healthy battery voltage there. I have therefore now concluded that the problem must lie with the control unit itself, but would would be glad to hear what the team thinks.

Thanks,

Alan
Click to expand...
I would Suggest that you check the voltage whilst endeavouring to start the unit. If there is no flow of electricity through the wires, except that necessary to drive the voltmeter, the voltage will invariably look healthy. Quite a few Amps are demanded by the heater during its start cycle and any significant resistance will proportionally reduce the voltage (Ohms law). I had a similar problem to you which turned out to be a poor connection in the in-line fuse holder. Eberspacher have used in-line fuse Holders of an uncommon type which can loose their grip on the fuse over time. They’re opened by swivelling one half against the other. You may well have one of those installed.
Mike
 
mikegunn said:
I would Suggest that you check the voltage whilst endeavouring to start the unit. If there is no flow of electricity through the wires, except that necessary to drive the voltmeter, the voltage will invariably look healthy. Quite a few Amps are demanded by the heater during its start cycle and any significant resistance will proportionally reduce the voltage (Ohms law). I had a similar problem to you which turned out to be a poor connection in the in-line fuse holder. Eberspacher have used in-line fuse Holders of an uncommon type which can loose their grip on the fuse over time. They’re opened by swivelling one half against the other. You may well have one of those installed.
Mike
Click to expand...
Unfortunately, as I mentioned in the post you quoted, the controller is unresponsive so I am unable to try to start the unit. I assume that as I have identified 12volts on the input to the control unit, its LCD display would be visible in the standby condition and it would attempt to respond to commands unless it were faulty.
 
PaulRainbow said:
Hmmm, i'm not sure what he means now Pete. I thought he meant there was power at the ECU/heater, but talk of spending £100 on a replacement sounds more like the timer/switch ?????
Click to expand...
I meant that there was power at the rear of the thing with the push-buttons and the LCD display which I use to control the system, which I have called the controller. It looks like this:timer-12-24v-d2-d4-d5-diag-p1376-253_medium.jpg
If I have understood correctly, if I short together the red and yellow wires at the back of this unit it should send an "ON" signal to the ECU. If that happens, can I conclude that it is this unit, not the ECU, at fault and go ahead and buy a new one?
 
Last edited:
alan_d said:
I think that the control unit of my Eberspacher may have given out, but before I splash out £100+ on a new one I would welcome suggestions about other possible diagnoses, or investigations I might usefully try.

My Airtronic D2 was professionally installed about 12 years ago and it has never given me any trouble, although I don't use it a great deal - just a few hours in Spring in Autumn. When I came to try it last September it was completely dead - the 24 hour/7 day control unit being completely unresponsive and looking just as it does when the battery is disconnected - no LCD display. At that time I suspected a blown fuse or a loose connection and resolved to check it out before the start of the new season. I have now spent some time crawling around in lockers tracing the wiring and looking for the in-line fuse that I expected to exist, to no avail. I couldn't find a fuse at all, and indeed I could not work out how the Eber was connected to the boat's 12 volt supply. There is a smart, well-secured Eberspacher wiring loom connecting the control unit, the cabin temperature sensor, the Eber fuel pump and the heater itself, but this seems completely self contained and not to be connected to anything else. I expected that the 12 volt feed would be somewhere close to the control unit, which is right next to the rat's nest of wires behind the main distribution/fuse board, but I couldn't find anything of the kind. I was planning to ask the collected wisdom here where I should be looking for the 12 volt feed, when I did what I should have done at the outset and checked the voltage across the wires leading into the back of the control unit and found healthy battery voltage there. I have therefore now concluded that the problem must lie with the control unit itself, but would would be glad to hear what the team thinks.

Thanks,

Alan
Click to expand...
yes Alan, as suggested check the voltage under load if you can, even put some other device onto the wires to imitate load like a 60 watt bulb?
If the voltage is good and you suspect the timer/control switch ( apologies for any early confusion but Eberspacher refer to the ECU as the control switch in the manual) then you can by pass the switch by connecting the red lead to the yellow one. Power issues are the single most common issue I find when customers get starting issues.
 
alan_d said:
I meant that there was power at the rear of the thing with the push-buttons and the LCD display which I use to control the system, which I have called the controller. It looks like this:View attachment 94771
If I have understood correctly, if I short together the red and yellow wires at the back of this unit it should send an "ON" signal to the ECU. If that happens, can I conclude that it is this unit, not the ECU, at fault and go ahead and buy a new one?
Click to expand...
Yes Alan if there is good power there then that connection will work. That is an expensive type timer but don't bin it yet ( there is one on eBay at £58 just now though!) (NOT MINE!) They rarely fail. If you don't want the time setting function then you can get something much cheaper.
Good luck
 
alan_d said:
I meant that there was power at the rear of the thing with the push-buttons and the LCD display which I use to control the system, which I have called the controller. It looks like this:
If I have understood correctly, if I short together the red and yellow wires at the back of this unit it should send an "ON" signal to the ECU. If that happens, can I conclude that it is this unit, not the ECU, at fault and go ahead and buy a new one?
Click to expand...

(y)
Gotcha now Alan.

I see Pete has answered the rest of your question
 
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