Club 80-90 Forums

I have acquired a D1lc compact for what would have been a bargain price, except that it isn't working

I am getting 12.7v measured at the ECU
Initially the controller had no power as the red wires and brown wires in the multiplug had corroded, and I fixed that (temporarily), it now sends 12v down the yellow signal wire to the ECU but no joy. Only sign of life is the led on the rheostat
It's possible that the wiring loom still has a few problems (especially as there are some hidden joins in the earths - although I can't see if they're corroded)

Any advice on narrowing down if it is ECU or wiring loom, or something else entirely?

I cannot help, but just to say that our member "Oldiebut goody" will be along soon. He is the expert on these.

E D I T = here is his profile, https://club8090.co.uk/forum/memberlist. ... ile&u=7143" onclick="window.open(this.href);return false; but ask him via this thread rather than pm, so that others in the future might benefit from the info.

Thanks, I've been reading through his advice and it's brilliant.
I found this thread about a D2: https://club8090.co.uk/forum/viewtopic.p ... r#p7627756

The start up sequence is:
On start up the indicator light illuminates and the following
sequences take place:
• Control unit does a systems check of the glow pin, flame
sensor/temperature sensor, fuel metering pump and control
unit.
• Blower starts slowly and begins to accelerate.

so you will need to check the components above.

Glow pin:
Check continuity of glow pin.
AIRTRONIC 12 volt - approx. 0.5 ohm ± 0.05 ohm

overheat sensor:
Temperature °C Resistance k/ohm min. max.
-40 /1597.0 / 1913.0
-20 / 458.80 / 533.40
0 / 154.70 / 175.50
20 / 59.30 /65.84
40 /25.02 /28.04
60 /11.56 /13.16
80 /5.782 / 6.678
100 /3.095 /3.623
120 /1.757 /2.081
140 /1.050 /1.256
160 /0.6654 /0.792
180 /0.4253 /0.5187
200 /0.2857 / 0.3513

flame sensor:
Temperature °C Resistance k/ohm min. max.
-40 /825.90 /859.60
0 /980.00 /1020.00
40 /1132.30 /1178.50
80 /1282.80 /1335.10
120 /1431.50 /1489.90
160 /1578.30 /1642.80
200 /1723.40 /1793.70
240 /1866.60 /1942.80
280 /2008.10 /2090.00
320 /2147.70 /2235.40
360 /2285.50 /2378.80
400 /2421.50 /2520.30

And the blower doesn't start in mine, so I guess that leaves us with voltage, lockout or it's failing the systems check. Glowpin and fuel pump resistance seem ok. I think I have to fully dismantle the unit to get to the other parts, so was wondering if I had missed something obvious.
Also, I've read that you can connect an LED (and appropriate resistors?) to the blue/white wire to see if it is flashing an error code. Might give that a shot...

Until "OGB" turns up, the only thing I DO KNOW is that they require a very healthy battery to fire them up. You quote 12.7 v at the ecu, which sounds fine, but does it maintain that voltage at all the relevant parts when you attempt to fire it up.

The worst thing is that I accidentally applied reversed polarity to it and blew two fuses (thought it was the wrong ampage fuse blowing, so fitted a 30A as recommended)! Am hoping that because it blew the fuses instantly that the diode did its job and the ECU is ok?


I did that because I didn't want to use the crusty green wires and ancient ceramic fuse provided with the unit... I did think to check the polarity, just had a moment of colour blindness.

At a minimum I should say that you have most probably burnt out a track or two in the ecu with the reversed polarity - it only takes an instant for that to happen. Or maybe a diode or two also. The fact that the fuses blew means that the circuit was completed. The fusing only protects the wiring against a direct short, not the electronics.

"Also, I've read that you can connect an LED (and appropriate resistors?) to the blue/white wire to see if it is flashing an error code. Might give that a shot..."

Across blue/white and brown/white - should already be present at the rheostat. The red led should give the error code.

I would have started by replacing all connections/dodgy wiring before anything else as you had found corroded connectors.
I could take a look at the ecu for anything obvious like dead components and replace them but cannot test it as I only have the Webastos that I work on.

Ok - thanks for that. Is it possible to dismantle the control unit myself and to see if there are burnt out components? I haven't seen any pictures of them dismantled - I have heard that the newer Airtronic ECUs are almost impossible to dismantle without breaking ...
I will probably send it to a professional like yourself!

Ahh - I didn't realise it was a RED LED that flashed on the rheostat when you bridged those wires, will try that later! I think I saw that flashing now I think about it

I will look at the wiring too - makes sense to rule that out first. I think some of the joins on the earth side seem to be inside the heat shrinking (I have looked at the loom wiring diagrams, but none seem to match exactly what I have)

Thanks for your support!

You could take a look- this is the type of thing to expect inside (Webasto one with basic functions and no multi-function chips)




- There will be a load of diodes around 1N4005/7 value that will all need checking, resistors will be apparent if blown - if they are blown you are on your own as to what value they were! Burnt tracks can be bridged with wire but check components connected to it for obvious faults.

The less joins you have in cabling the better - far better and easier to replace the whole length and terminals.

Oh - that's brilliant, it doesn't look as bad as I thought it might.
I will dissect the external wiring before trying the ECU...
It would be brilliant if it was wiring, but we'll see!

First things first - wiring. I guess the most important are the power wires, then the three main wires to the rheostat. A lot of the others are sensor wires and the diagnostic, etc? I presume it'll fire up with an open circuit on all others?

The latest:
Dissected the external wiring yesterday and today, doesn't seem too bad. Some resistance present in some leads (esp fuel pump power - 3ohms iirc, with only a 30cm length of wire) - so might try to cut back the wire and crimp a new end to see if it improves, most of the rest are ok now

Both flame and overheat sensors are measuring about 1.06kohms, which seems correct
Blower motor resistance is also slightly high (3.3 as opposed to suggested value of 0.5). Blower seems to spin quite badly when moved by hand - it was catching on the ECU and rubbing quite badly. Tried to pry it away and it's slightly better now but still clicks against the ECU
Bear in mind, blower doesn't turn at all when heater is plugged in...

Took ECU out but didn't want to mess around with it too much... Back of it looks ok, but there's not much there, probably all the interesting parts are on the heatsink side
Connected an LED over the blue/white wire and brown, and didn't get any flashes at all...

Someone has offered to check the ECU for me for the price of postage, so I might do that before I tear my hair out...

Disconnect the fan and apply 12v directly to it - easy check to see if it has been b*******d.
You mention the fan catching on the ecu - are you sure that you haven't got a D1LCc model and not a D1LC? The ecu on a D1LC is separate from the heater.

It is D1LCC - D1lc compact ...
I read somewhere that it is 8V so wasn't going to try supplying 12V to it?

Sorry missed the compact - so ignore the ecu reference above!!!!!!! Got confused with the reference to the Airtronic.
I would just knock the voltage down but I don't suppose you have a regulator lying around like I tend to have. A LM7808 1.5A would be good enough to test it with.

Check that the little magnet in the fan hasn't started to come out and is catching on the ecu (forms part of the speed sensor circuit)

Hah, no problem
Got the fan turning, but when the ECU was in originally it didn't want to turn...
The blower motor wiring routing and where the heatshrink was located meant there was a bit of interference, moved the heatshrink down and it's better now - runs on 5v (all I could find!), but still no joy from heater.

I definitely think it's locked out now. Might see if I can get a lend of a timer / diagnostics unit from someone...

Have just realised - even if it's locked out, it should be flashing a code over the blue/white wire? Am quite puzzled now...