Yet another D4 Ebers enigma - Test ECU at dealers?

[RIBW]

Sorry to add to the spate of Ebers questions.
My on board D3? has been trouble free for 5 seasons because I have threatened to replace it with the D4 I use to heat the garage occasionally in the winter. Now the D4 has failed and I am at the point of taking it to a dealer for diagnosis unless a forumite comes up with an idea. The situation is:-

The controller is a blue 701. The battery is a boat starter battery (800CCA) and is supported by CTEK 25A in supply mode.
D4 has no in or out heated air ducting.
Combustion air is taken from the garage - no duct. Combustion gas (exhaust) outlet is less than 1m to outside the garage

Fuel is Red diesel old but debugged. Pump pumped well on first start.

Ambient air temp was less than 5C

Controller shows no fault codes just _000

Start 1 was normal, heat was produced for several minutes and I went off to do something elsewhere leaving the D4 running. After, I'm guessing, 10 minutes the fan was running but there was no heat.

Start 2 got as far as pump start but pumping ceased and the fan ran fast.

Start 3 and onwards, the fan just runs fast - no pumping or high current to the glow pin. I have tried restarting with min and max temp setting on the 701 and without the CTEK charger attached.

I then took the D4 to the bench and found the following
Flame Sensor, Glow pin and pump resistances were all within spec.
The overheat sensor read 54kohm which is about 10% below the minimum spec.

I hve checked the Letonkinois and ESPAR fault finding info. The nearest scenario I can find is No4 on the ESPAR fault finding list, namely,
"Being turned on, heater just blows cold air, never stops and never performs a start attempt. No fault code recorded."
Their fault reasons are
"1.Was “Ventilation” button pressed instead of “Heat”?
2. Replace combo Sensor.
3. Replace ECU if necessary."

No 1 is quite difficult to achieve accidentally on the 701 so it is either No2 or 3.

Anyone have any other thoughts?
Cheers
Bob

 

[matthewriches]

What age is it?

 

[RIBW]

What age is it?

The year of manufacture was probably 2005. I have had it on garage duty for about 4 years.

Thanks for your interest
Bob

 

[pcatterall]

The year of manufacture was probably 2005. I have had it on garage duty for about 4 years.

Thanks for your interest
Bob

The fan running only ( when all else is checked)symptom used to be common on D2s with the older ECUs ( the one with the heater tail leads encapsulated rather than wrapped in tape).
If all else fails you can send the ecu to me for testing £10 to the sally army plus you pay the postage.

 

[lpdsn]

Just a complete guess that it might be coked up, try running it on Kerosene for half an hour or so.

 

[ghostlymoron]

Forget it and get a fan heater for the garage.

 

[pcatterall]

Just a complete guess that it might be coked up, try running it on Kerosene for half an hour or so.

No ! it has stopped pumping! When coked up the start cycle works but the heater wont fire up lots of unburnt fuel inside and white smoke billowing out!

 

[RIBW]

Forget it and get a fan heater for the garage.

That would just tempt the D3 on the boat to fail, knowing it is no longer threatened!

 

[RIBW]

The fan running only ( when all else is checked)symptom used to be common on D2s with the older ECUs ( the one with the heater tail leads encapsulated rather than wrapped in tape).
If all else fails you can send the ecu to me for testing £10 to the sally army plus you pay the postage.

Peter,
Can I presume you meant those older D2 ECUs had all failed to cause that symptom! If that is the case, I might go for buying one of the later model D4 ECUs which would give me a more reliable spare - no point in having an unreliable/susceptible boat spare.
Cheers
Bob

 

[pcatterall]

Peter,
Can I presume you meant those older D2 ECUs had all failed to cause that symptom! If that is the case, I might go for buying one of the later model D4 ECUs which would give me a more reliable spare - no point in having an unreliable/susceptible boat spare.
Cheers
Bob

Not as bad as that. Some years ago when the older ECUs were still being produced I had a spate of heaters with failed ECUs ( I must have thrown 20 away), it was the most common cause of failure in heaters coming to me
some 50% of those failures were where the fan only would work. I observed that the fan would come on straight away rather than 'wait' a few seconds for some ECU checks to occur. I did find a very short term fix where if I removed the temp setting leads ( the red/slate and the brown/white) then the heater would work albeit without any heat setting function. Soon after they failed completely anyway!!. I guessed that the ECU was somehow failing and going into a fan only mode. We did 'break into' several ECUs to see if the fault could be located but to no avail.

If your ECU has failed then a replacement should be the newer Hella type. I am building up a small stock of HELLA ECUs but only for 24 volts, this because they are now more reliable and I am cannibalizing heaters due to other reasons now rather than the ECU ( mainly fan motors and corroded away exhaust/inlet ports!)

 

[RIBW]

Peter,

....some 50% of those failures were where the fan only would work. I observed that the fan would come on straight away rather than 'wait' a few seconds for some ECU checks to occur. I did find a very short term fix where if I removed the temp setting leads ( the red/slate and the brown/white) then the heater would work albeit without any heat setting function. Soon after they failed completely anyway!!.

I checked out this possibility earlier today and found as follows:-
1. Disconnected Red/Slate wire between the 701 and the D4
2. Start up was normal (increasing fan and pumping) with no smoke whatsoever
3. All was OK for 9 minutes then both fan and pump slowed down in concert
4. At 11 mins the pump stopped. The fan keeps going at a slow to medium speed with heat still being pushed through (i.e. unit cooling)
5. At 16 mins the fan slowed to 'just about turning' and then kept going at that rate
6. No fault codes were displayed.

Hours later, I tried a restart and the fan ran continuously as yesterday - no hint of a restart

If your ECU has failed then a replacement should be the newer Hella type.

Looks like I need to start looking for a Hella ECU

Thanks for the pointers
Regards
Bob

 

[pcatterall]

I sometimes get good HELLA ECUs from manky looking heaters and cheaper than buying used ECUs plus you get other serviceable spares.

 

[RIBW]

I sometimes get good HELLA ECUs from manky looking heaters and cheaper than buying used ECUs plus you get other serviceable spares.

Peter,
That's a very good thought! As it is only a spare unit (for the boat) at the moment, I can afford to be patient in looking for such a beast on eBay et al.

I had a quick look at buying new - the best price so far including P&P and VAT is about £230 at HEATSO.

Thanks for all your guidance.

Regards
Bob

 

[Steve_N]

By the way, if you're wanting to get the of age of a secondhand Airtronic then look at the bottom of the label where there'll be a range of 3 years and it will have been produced in the first one.
'Erste Inbetriebnahme' = first time in service, so even better if the installer actually marked in which of these 3 years it was installed.

Here's the label on my still pristine 2005 D4.

 

[RIBW]

By the way............

Thanks, mine is 2005. I understand the new Hella versions of the ECUs were introduced in about 2008.
Cheers
Bob