Vito 2012 cdi w639 OM651 nearside Front indicator not working.

[Staunch]

Hi All,

I need help fixing a problem with a Vito nearside front indicator not working. I’ve read about the bulbs etc and a few other things but, plug the lamp into the other side and it works. I have no voltage at the pin when it’s switched o. When off I have no 5 volt reference. Which the other side has when it’s switched off.

it’s just had a new SAM unit.
earths are obviously good.

many help will be gratefully received.

 

[mattkh]

If the nearside rear indicator is working then it cannot be the indicator stalk.

 

[M80]

Assuming your SAM is good it would then be more likely to be the wiring to the unit, or the unit.
Be careful not to be fooled by a lack of voltage as the SAM removes the feed to units when it sees a fault, such as no load.

The lamp holder slots in and rotates for a contact to the lamp. It may be a breakdown in the contact or the lamp holder.
Have you tried installing the right lamp holder into the left headlamp unit?
Be sure to cycle your ignition to reinstate the supply to the left.

Of interest was your SAM plug and play as it is for earlier models?
It's always nice to know when MB make things harder for us.

 

[Staunch]

Many thanks for your replies.

rear lamp and wing repeater working fine. The Sam was just a plug and play type I assumed. Using a snap on scanner post fitment there were no codes. I’m guessing it would register a canBUS fault in instrumentation or the engine if it needed coding??

if the harness was repaired prior and somebody patched a piece in that was a thicker gauge wire would that effect it?

I have put the nearside lamp unit onto the plug on the offside and all works fine ?

 

[M80]

If it all works (ignoring the indicator) then no coding required.

If a wiring repair connects as it was, the gauge would make no difference.

If some one was clumsy reinserting the lamp holder it might damage the connections. You might take a photo with your phone with the lamp holder removed, to try and see if all is good at the headlight unit.
You might unplug the multi plug to the headlight unit and check for a flashing 12 volts there, before the SAM trips the feed.

 

[Staunch]

Ok I’m with you. So cycle the ignition a couple of times. Ignition on, indicator switch on to left and check the feed at the black/white cable at the pin?

I found the black and white cable at the SAM which I was able to back probe with a meter and that’s got an indicator voltage (fluctuating) but no way of telling if it’s for the rear or wing repeater?
Thanks for your time and will report back.

 

[M80]

You would find it easier to take meter neg to a ground point,
then your only probing for the pos.

Don't push your probes to hard as you can flare the connection and cause a failed connection at the headlight unit in future. Needle through cable can work but might cause loss of blood, or a screw into the connection of comfortable size to fit.

 

[Staunch]

Very good advice!
I do a lot of electrical fault finding on vans and MB always have another layer of engineering attached.

have another later Vito in the shop and that’s lost the dipped beam and indicator on that same nearside front! What’s the betting it’s a couple of bulbs!?
Thanks for your help it’s very much appreciated.

 

[M80]

Very good advice!
I do a lot of electrical fault finding on vans and MB always have another layer of engineering attached.

have another later Vito in the shop and that’s lost the dipped beam and indicator on that same nearside front! What’s the betting it’s a couple of bulbs!?
Thanks for your help it’s very much appreciated.

Does that mean you've solved the original fault?

 

[Staunch]

No I’m afraid not. The van is one of our service vans and I have just replaced the timing chain set and cleaned the intake etc. I’ve had to bring a new wire from the Sam which makes it work but fast as of a bulb has gone. ( no dash warning lamp for bulb failure and hazards all work at normal speed)

I will take a look at the fault again when I have repaired some other vehicles in with faults keeping them off road.

I will indeed report back once repaired properly.

many thanks.

 

[M80]

No I’m afraid not. The van is one of our service vans and I have just replaced the timing chain set and cleaned the intake etc. I’ve had to bring a new wire from the Sam which makes it work but fast as of a bulb has gone. ( no dash warning lamp for bulb failure and hazards all work at normal speed)

I will take a look at the fault again when I have repaired some other vehicles in with faults keeping them off road.

I will indeed report back once repaired properly.

many thanks.

Is my assumption correct that you have tapped onto the rear indicator feed?
I would still 'assume' that the load seen by the SAM would cause the flash to be normal speed.
No lamp out warning would still sound like a SAM issue to me.

Could the SAM be 2nd hand and also faulty.
Could you swap SAM's out with another of your vehicles to see where faults are transferred / cured?

I keep a SAM with known issues for that purpose.

 

[Staunch]

Yes you are correct. Once cut rear indicator stopped and wing repeater.
SAM unit brand new out of the box.

I will start again testing with lamp plugged in just in case it had switched off the feed. But.. I did a lot of this testing with the front end removed. Also with the new SAM unit installed. With both headlamps removed and unplugged I expected to see the same Voltage values at the puns on both sides. The right hand indicator pin in the plug when not switched on had a 5 volt reference present with ignition on but the left did not. I think it’s a wire interruption.

which then poses the problem why is it flashing fast by snipping/joining into the rear? Unless I’ve got to find the dedicated wire for the front from the SAM? If you have a bulb failure on the indicator circuit the dash warning says “Front” or “Rear” I believe?

I’ve used earths on the inner wing (which I’ve cleaned and tested) earth straight off the battery from a power probe (no probing carried out)

I have also renewed the earth to the tail lamp holder at the back.

I’ll be dreaming about it soon! That’s bad! After that it’s full blown PTSD

 

[Staunch]

Hi All (M80)

so I have the vehicle in tomorrow with the indicator fault. I’ve had a look at a wiring diagram generated from Autodata and pins 20 and 28 at the SAM are both black/white wires but for front and rear indicators. I hope this is my error and it is just a wire broken but I patched into the wrong black/white wire. I can’t find any image or diagram to help find it in situ to save time. I’m confident this is it though. However, there is a indicator control unit in the diagram. Is this the trailer control unit or is it something I have overlooked?

 

[Staunch]

Hi all

thank you for your help and suggestions with the indicator fault. After looking at the wiring diagram I found a broken wire from the SAM to the indicator. I had thought it was this but connected into the feed for the rear indicator at the SAM. The front is a slightly thicker gauge wire but same colour and tracer. Thanks M80 for steering me along, logical in the end..

Regards

 

[Staunch]

Is my assumption correct that you have tapped onto the rear indicator feed?
I would still 'assume' that the load seen by the SAM would cause the flash to be normal speed.
No lamp out warning would still sound like a SAM issue to me.

Could the SAM be 2nd hand and also faulty.
Could you swap SAM's out with another of your vehicles to see where faults are transferred / cured?

I keep a SAM with known issues for that purpose.

Thanks M80

 

[ante1982]

Hi

So i have the same problem, did you figure out the problem?

My 2005 vito w639 left blinkers blinks faster along with my rear heater unit's relay clicking in synch with it, also the small indicator light on the rear heater button blinks in synch with it. The rear door lock also makes sounds. I get weared brake pads warning but its false, the car's sentral lock doesent lock all doors. I have tried to replace the whole SAM unit with no luck. All the bulbs are correct. My suspision is that there must be a short circuit somewhere, but where are the common places of such things on a w639. My car is also an ex handicap car if that has anything to do with it. Im out of ideas anyone who might know or heard of these types of faults?

 

[M80]

Bad common chassis connection possibkly.

There were different SAM type to earlier Vito, were you sure the numbers matched?

 

[ante1982]

Bad common chassis connection possibkly.

There were different SAM type to earlier Vito, were you sure the numbers matched?

Hi and many tnx for replying. How can i test that "common chassis" connectivity? With a multimeter on some terminals on the SAM maybe?.

I ordered the exact same part numbered SAM module to the car. And no results.

Can the doors damage cables and cause shorts anywhere in this car?

Is it possible to buypass the whole SAM and make unique blinker circuit?

 

[M80]

Hi and many tnx for replying. How can i test that "common chassis" connectivity? With a multimeter on some terminals on the SAM maybe?.

Really you need diagrams to show you where the common bolt down points are, and check for rust / looseness.

I ordered the exact same part numbered SAM module to the car. And no results.

There is possibility that the replacement SAM is faulty, I'm assuming it was an Ebay breakers SAM (I've had a few).
What is the number? I have a SAM her with a couple of known faults. I keep it just in case. So that I can install and see if other faults disappear while the known faults are introduced, in that case I know for sure the SAM is would be the culprit.

Can the doors damage cables and cause shorts anywhere in this car?

I don't see that one. The pads can loose connection, bu then that's only door related.

Is it possible to buypass the whole SAM and make unique blinker circuit?

Always possible, I suppose you could break the feeds to each indicator and feed from an independent flasher unit.

 

[ante1982]

Ok thank you for your advices. Former owner has routet a cable from the SAM (or from the front) that goes dierctly to the right rear blinker bulb. And if i loosen it the right side blinkers also start to blink fast as expected, but why route an independent cable? Maybe its a part of the aftermarked trailerhitch socket box thingy. There was a mess of cables, i have removed the whole box with its cables now. But really not sure where to search next? Maybe the ground points of the car.