SAM Unit resistors value

[dream19]

Hello guys!

I have a Smart Fortwo CDI from 2004 (sorry, I know it is an area for 2005-2006 versions) with a 800cc Diesel engine. I have had many electrical problems since i bought it 3 months ago, and the principal suspect it is the SAM unit, possibly due to water infiltrations.
At the moment my low beams dont work at all (i fixed them a while ago, a resistor had an imperfect contact). Now the same resistor is broken and registers a high resistance value, so probably it must be replaced. Taking the unit to a MB dealer would skyrocket the bill, and even then probably they will just replace it andf cost me half the car price.

I don't have and didn't find an electrical diagram of the unit so i'll have to ask a fellow smart owner: can you measure on your SAM unit (or even a functional spare one) and post some resistors value for me? I attach a photo with the resistors in question (marked with a barely visible red rectangle).

Thank you very much in advance!

PS: The resistors in the attached photo are under the N11-9 connector, as seen here: http://www.fq101.co.uk/images/450/electrical/SAMconfig.jpg

Edited August 20, 2015 by dream19

[tolsen]

Surface mounted restors usually have their values marked on them.

[smartdriver]

Those are not all resistors.

Half of them are capacitors to ground which combined with the resistors form a noise filter for the inputs.

I don't remember the values, but they are not critical. The value may be determined by measuring the resistance of the adjacent resistors with an ohmmeter. The capacitors of course, if isolated, should measure as being open.

http://clubsmartcar.com/index.php?showtopic=27439

Edited August 21, 2015 by smartdriver

[dream19]

Thanks for clarifying that not all are resistors.

So basically the component indicated in the attached image is a capacitor? If so i misdiagnosed the problem and I'm all lost.

[smartdriver]

The component in question is a capacitor.

The resistors are 47,000 Ohms (47 with 3 zeros).

I would agree that this appears to be the low beam input from the stalk. I would check the continuity between the input pin and the following circuitry.

As a last resort I would check to see if there is continuity from one side of the board to the other in the plated-through holes in this area.

Corrosion can eat away the plate-through copper, but it can be fixed by installing a fine jumper wire in the hole and soldering both sides.

On the photo below, there should be continuity between the ends of each yellow line. It would be worthwhile checking the continuity path for Pin 35.

Edited August 21, 2015 by smartdriver

[dream19]

Hello!

Thanks for the advice. I have did the continuity measurement by setting the multimeter to the diode symbol, which produces a beep sound when you touch the leads. Correct me if it isn't the correct way to do it.

I have measured for continuity the following:

- the small yellow lines from pins to the tiny holes: measuring for all pins produces a beep, including the low beam one

- the long yellow lines from the right side of the image: measuring all indicates some number on the multimeter but do not produce a beep

- the orange lines: all produce a beep

Edited August 24, 2015 by dream19

[smartdriver]

Your test technique is perfect!

The long yerllow lines should also beep for continuity. Please test again and make sure that I haven't accidently shifted the long yellow lines to the left by one position in the photo.

The long yellow lines should go to the resistors, not the capacitors.

The yellow lines in the photo below indicate what I believe to be the continuity path for low beam from the stalk (Pin35)

Edited August 24, 2015 by smartdriver

[dream19]

So i have re-measured all yellow long lines, from the resistors this time, and i get a beep for all of them.

I get a beep for the low beam too but on the green line not on the yellow (from your last post).

[smartdriver]

Your beep is correct, my beep is wrong. Sorry!

Tough to science this out without the board in front of me.

Your measurements would imply that the signal path in the SAM is correct, which might suggest a number of other possibilities.

1. Corroded Pin 35 on connector N11-9.

2. Bad wiring harness.

3. Defective stalk switch.

4. Bad or sticking relay

http://www.fq101.co.uk/how-to-guides/fortwo-450/electrical/252-relay-config-450.html

5. Bad output connector (the brown connector N11-3). Some individuals have had a problem with this connector melting because they replaced the stock headlights with higher wattage units and this connector was unable to handle the load and melted.

http://clubsmartcar.com/index.php?showtopic=25663#entry299951

6. Blown fuse. I don't know whether this might be a possibility, but it would be worthwhile checking the wiring tables at the FQ101 site. Each of Pins 6 and 7 of connector N11-3 (the left and right low beam outputs) are fused.

http://www.fq101.co.uk/how-to-guides/fortwo-450/electrical/251-sam-wiring.html

I don't know what else to suggest. I would be grateful if you do figure this out, if you would post your results

here.

Edited August 25, 2015 by smartdriver

[dream19]

Hello and thanks for the suggestions!

I have tried almost all of them: the cable harness has continuity, the stalk opens and closes the circuit properly, no blown fuses, no melted connector, no corrosion on pin 35 or in its connector.

I haven't checked yet the relay.

I have another side - question: when switching to high beam it is normal that both beams (high and low) are lit? if so, how does the low beam gets activated in this case?

[kramma]

I am interested to know if anything became of the fuse inquiry. I am trying to find out the ohm value of a fuse here...

https://drive.google.com/open?id=0Bz...kFPYVdvdDJPLVk

Its the one on the very right of the picture denoted by the arrow

Thanks for any help
K

[smartdriver]

That is not a fuse, it is a resistor, likely 47K (473) Ohms like all the rest.

 

Your board looks like it is badly water damaged. At the very least it should be cleaned with a toothbrush and alcohol. I find it interesting that part of it appears to have a resin coating.

Is this something that you added?

 

Hopefully the link below may provide some helpful information.

 

http://clubsmartcar.com/index.php?/topic/27439-some-information-which-may-help-others-repair-water-damage-on-their-sam-circuit-board/

 

The photo below is from the latter part of the above link and shows yellow lines which should have continuity when measured from end to end with an Ohmmeter. Similarly so should the orange lines.

 

If my count is correct, the missing resistor goes to N11-8 Pin 38 which according to the wiring diagram below, is Ignition Switch In Position 2.

 

Also according to the wiring diagram, Pins 36 and and 37 are not connected to anything, which means that you could steal a resistor from one of these locations and replace the missing resistor which connects to Pin 38.

 

Edited February 13, 2017 by smartdriver