one last try

[joderest]

Since buying my ML270, i have investigated and cured all its faults except for two, no one i have asked has any clue about these two faults, so thought i would try one last time before giving up, even Mercedes have no clue, and just want to swap parts until it goes away.
1) Windscreen air flap.
The Fault >>> Start car in the morning or what ever is first start of day, all the directional flaps will work except air to windscreen, drive car a mile down the road, stop engine, count to ten, re start car, select air to windscreen, after about a 5 second delay, flap will open. It will then work as it should unless car left again for 10 hours or more, then back to square one.
What has been done>>>> Air flap motor replaced, all wiring checked, flap motors all set up on STAR (worked for a week, then back to square one), battery replaced as showed low voltage, all flaps checked and working when moved by hand.
2) Parktronic>>> front left side, intermittently goes faulty, MB2 gave outside left sensor faulty, replaced sensor, still the same. Got under bumper and disconnected wiring block, cleaned and put back, all this did was move fault to next sensor, did it again, fault back on outside sensor. MB2 shows 5 front sensors at 255, outside left sensor at 63. tried replacing sensor again, same readings same fault. However, some days works perfectly.

I have no hair left now due to these last two issues, rest of car is now good. Does anyone have any ideas of what to check, do or what ever.

Thanks

 

[joderest]

ok, all stumped then !!!!!!
Well, i have tried something which i do not understand.
when you first put the key in the ignition and turn to first bit, the fan comes on (even though turned off) i can hear all the flaps moving, after about 20 seconds this all stops.
Like any other diesel car i have owned, i always wait for glow plug light to go out before starting.
Last three mornings i have sat waiting for all the noises to stop, about 2o seconds, and then started car, on these occasions the windscreen flap has worked straight away.
Questions......... what is the car doing during this event, fan heater fan running, flaps opening and closing?

Is it that its doing some sort of test procedure, and starting car before its done it is making it fail , hence windscreen flap will not work ? maybe starting takes voltage away from this procedure ?

I will stop now as confusing myself

 

[John Laidlaw]

I must admit to being a bit stumped on this but at least felt I should acknowledge your post otherwise you may think you’ve been talking to yourself!

 

[joderest]

Thanks John
I have even spoken to a long serving Mercedes diagnostic tech, and he was stumped as well. When i spoke to Mercedes local, they said book it in and we will change, AAM, the extended module as well, all heater motors, take dash out and check wiring etc etc etc.
I declined.
I have discussed with my local auto electrician, who also runs an ML (later one), and he cannot come up with any reason.
I think its something i am going to have to live with.

 

[joderest]

Bump

 

[Botus]

put a charger on the vehicle for an hour or two before starting the car and see if things work correctly
you may have something draining the battery till it drops to a low voltage situation and misbehaves

on the parking sensors check resistance of each and remake all connections.... then swap out the control unit from another car

its quite likely the car is at end of life and fighting an ever increasing list of failing control modules isn't worth the effort. 15 years for cars built/designed pre 2005 is about right. later stuff speeded up with pre 2010 lasting circa 7 years and current production of german cars lasting around 4 to 5 years. we get away with it because your manager's manager gets 15k a year to lease a car and 100k of your last 15 years pay rises in his wage packet. And if that didn't leave your poor enough to worry about other stuff. We pay kim yong un to make a noise and bomb Syria till you think what you have means you're lucky.

another point people often seem totally ignorant of is the software in modern cars is complex and interferes will all elements of how everything works (via the can bus). yet no one ever updates the software - even when quite a few modules will have had available for many years later bug fixed versions that should be applied (if this is a 2003 car all that is far less likely - but might be worth a check)

 

[joderest]

Thanks. Car has only done 40.000 miles, which is genuine mileage.
The last four mornings I have tried something else. Wait for all noises to stop, then look at Speedo, the mileage indicator will go to a series of dashes, then return to miles reading, start car, the flap has opened every time. If I do not follow this start faff, it will not open until I stop and restart.
The battery is new, and after left sitting overnight comes up with 12.8 volts with volt meter.
I did a draw test, and it was within limits. 0.3 to 0.4 Milli volts.
They are an odd besst

 

[joderest]

On parking sensors, it has behaved well for last week, then last night went wrong again. I think it's a wiring problem which means removal of front bumper, which at the moment I have no time to do.
Each time it misbehaves, when checked with MB2, shows a stored fault on left front outside sensor, which can be cleared until it happens again, hence why I think it's wiring issue.

 

[joderest]

DAM, i should have kept quiet !!!!!, process did not work today, so thats not a fix, had to restart twice before defrost flap to screen would open.
back to drawing board, I am starting to think again that it is voltage related, maybe an intermittent draw from something, might try not locking car tonight and see what that does.
( a Kia Sorento is looking good !!!!) as need tow car.

 

[Ken_R]

What is the manual flap reset sequence on that vehicle? I'm thinking along the lines of there being a fault/dirty contact in one of the switches which is triggering the reset sequence.

 

[joderest]

there is not one for the W163, can only be reset using STAR

 

[joderest]

Bang head, bang head, someone said smile, it could be worse, so i smiled and yep, it got worse.
The defrost flap stuck in open position, ok, its what i wanted, air to screen, but try driving at night with the aircon on cold, the screen condensates on the outside !!!!!!
SO, searched google again, and found something that said on Mercedes you can reset flaps by holding down defrost button and recirculate button and turn ignition off holding said buttons, thought worth a try.
BUT, on the ML those two buttons are on a rocker switch !!!!, so cannot be done. Out of frustration, held down
defrost, everything blowing like mad, turned off ignition, counted to ten, released button and turned ignition back on.
Hmmmmm, defrost flap now closed and works, BUT flap that controls air to rear now does not open, so something happened, what, i do not know.
IF all the rest work for a few days, i will disconnect the air to rear flap in the open position, and then connect an old motor i have so that ECU still thinks theres one there.
I have never known a car to have this sort of issue with its ventilation system. every thing else controlled by the AAM works fine, so i do not think that is faulty.

Frustrated is not the word

 

[Ken_R]

Are the flaps still cycling as in post #2?

 

[joderest]

yep, they still do their thing before start up, also fan runs as well.
if you start engine before they have finished, they carry on anyway. I have never had a car that goes through this process, but there again, first Mercedes.
to say its driving me nuts is an understatement.
If, and its a big IF, they stay as they are, i will disconnect the motor that controls the flap that lets air to the rear heater, and leave it in the open position, and then connect a spare motor, and fix it in there, just so the ECU does not think there is a failed motor and throw up some sort of code.

 

[joderest]

An update.
I have not fixed the heater flap issue, but have discovered a work around.
If I leave it set on screen demist, and start car in the morning allowing all the checks to take place first, 9 out of10 times it works.
I willl have to live with that as it's the best I can get, at least this winter I know I can defog the screen when I need to.

 

[Craiglxviii]

THis sounds like water contamination of the wiring harness somewhere... intermittent faults like this usually end up being shorts somewhere along the line.

 

[joderest]

If the car did not do this process when starting I do not think there would be a problem
What it does, turn ignition on, you can hear the heater flaps moving, the heater fan comes on and runs for about 10 seconds, the mileage in the Speedo then goes to dashes, the fan stops, the flaps stop, the mileage goes back to numbers.
If you do not let the car finish this cycle, the windscreen flap will not open, let it do the cycle and 9 times of of ,10 it's fine.
I hate electronics

 

[joderest]

Update for you all
Heater, the work round still works, 8 times out of 10.
Parktronic, well, replaced the outside left sensor three times, each time it came back again faulty, so bit the bullet and pulled off front bumper to check wiring, all appeared ok, so properly stumped.
Then i noticed that the wiring to front outside left sensor was quite tight, the wiring to the left middle sensor was very loose, so swapped them over.
Fault then came up on left middle sensor, replaced that one and its been fine ever since.
I suspect in its previous life before me someone for some reason has removed front bumper and sensor wiring, and got them swapped, hence middle sensor faulty, but showed up as outside sensor.
Its all i can think of !!!!!!!

 

[joderest]

Thought i would update on my heater flap issue.
I have not been able to fix it, but think i have found a 100% work around, which has worked for last three weeks.
If i leave the heater blower on low setting, and the direction on windscreen and then turn off engine, when started again next morning it all works as it should, it does not seem to do the test thing (flaps opening and closing and blower running for a few seconds)
This has worked every time so far, and the system can be used as normal all the time.
Might help someone else out.

 

[Blobcat]

I think you have a wiring issue somewhere along the line, I just fixed a car that the stereo kept switching itself off then restarting. It was completely random, you could listen to it for ages and then it would just cut out and then restart. I took the radio out and checked all the connectors, I then investigated the wiring and noticed that there were cracks in the insulation on a great many of the wires. I went through each one wrapping them individually in insulation tape and then taped the loom up. Refitted and a good few miles and days later and it's not switched off once.

I'd be looking at water in connectors and broken or shorting wires.