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Ask Juan Crespo Your Own Question
Juan Crespo
Juan Crespo, ASE Certified Technician
Category: Mercedes
Satisfied Customers: 1514
Experience:  A.S.E. Master Technician, Advanced Level, Emissions - Asian, Domestic, & European
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I have a 03 sl5oo. the right front turn signal wont work

Customer Question

i have a 03 sl5oo. the right front turn signal wont work bulb and socket has been replaced. all other lights work like the lt rear and led left .the rt led rt rear all work. that hase been going on about three weeks the other day the leth frount turn sig plus AC went out at same time.tell me about all the SAM units
Submitted: 11 months ago.
Category: Mercedes
Expert:  Juan Crespo replied 11 months ago.

Hi there. Thanks for posting your question.

SAM modules carry the heavy electrical loads computers can't. In your particular case, when you actuate the turn signal lever upwards, the turn signal module sends a signal through the CAN netwoork to the corresponding SAM module (driver's side in this case), which then sends 12 volt power to the right front turn signal lamp.

The ray of hope on all of this is that removing the SAM and cleaning the connections with WD40 solves the problem 50% of the time. See attached pic showing driver's side SAM location.

Best Regrds.

Customer: replied 11 months ago.
Juan, i got to the SAM ,now do i have to take the unit out to clean with wd40,i took a Q tip cleaned the long male plug ,how do i clean the female part that the male part plugs into? Do i unplug the connectors at the bottom of the SAMs, are the plugs all made like you canot plug then in wrong?if you buy a new SAMs MB servise has to progmem right? Now can the old SAMS be reprogramed? It about 400 bucks if i order it, ,at MB im sure itll be like a $1,000.
Expert:  Juan Crespo replied 11 months ago.

Yeah, I'm afraid you're right about the cost of buying and programming a new SAM through the dealer...

Regarding removing the current unit; yes, all the plugs are made to fit properly. Spray WD-40 liberally on all sides of the connections (WD stands for "water dispersant"). Should not need reprogramming.

Best Regards.

Customer: replied 10 months ago.
Juan,ill be glad to rate you 5 stars, an i will . I asked if the A/C control is on the SAM that ill remove? If this SAM after its clened with wd40 still dont/ work,can it be reprogramed ?(whaqt do you mean when you say the LAN turns on the SAM? can i get a list,copy or schamic of inputs and outputs of this SAM? ill be the 50% what then?
Expert:  Juan Crespo replied 10 months ago.

I apologize for the late response - power failure.

I'm sorry for having an old engineer's mind, but all I saw was "the leth frount turn sig plus AC went out at same time." Didn't the A/C fail but become operational again on its own? - that would make it a SAM problem.

If the SAM itself is bad and cleaning the connections with WD-40 doesn't work, reprogramming it won't fix the problem. The failed unit must be replaced and the replacement programmed.

One more time I need to apologize for how my mind works, but what and where did you read something that I stated that made you ask "(whaqt do you mean when you say the LAN turns on the SAM?". There is the CAN network through which on-board modules communicate. Is that what you're asking?

Mercedes puts out sophisticated schematics and diagrams meant to be interpreted and used by their own certified technicians so those won't help you much and that's what I have access to through their tech website - suscription about $4,500.00 per year. Instead, you might be better served by purchasing a Haynes manual for your vehicle that includes a simpler version of the diagrams - available online and at foreign car stores for less than $30.00.

Lastly, wat do you mean by "ill be the 50% what then?"

Best Regards.

Customer: replied 10 months ago.
Juan,the turn sig on the left front AND the A/C went out at the same time.Nothe AC and turn sig both are still out. LAN where did i recall that from i guess its from my electronic back ground (old and retired now, 32 yrs Air F0rce Aircraft radar and any nav system OK CAN what kind of sig does the Can transmit Ok Juan after i clean up thisSAM amd no fix,what are where do we go now?.
Expert:  Juan Crespo replied 10 months ago.

Welcome to the "old and retired" club ;-).

Regarding CAN bus, click here to see an article from Pico scopes.

If cleaning the SAM connections don't bring back at least the turn signal (there is a chance the A/C has a different problem that has to be diagnosed on its own), then it's back to Mercedes where they would have to install and program a new unit.

Best Regards.

Customer: replied 10 months ago.
Jaun is the a/c controled by the SAMS? At the very same time the turn sig went out the a/c went out. I took flashlight and shined it on the compreser the cluch is not puling in.DO you not have a digram that shows pin numbers on theSAM and what it controls? Can you tell me is this SAM a relay unit? the 50% thing is you said " workes 50% of the time,and i said ill wont be inthe 50%
Expert:  Juan Crespo replied 10 months ago.

I'm sorry but it seems I'm not able to effectively communicate with you. I'll opt out and reopen your question to the field so other experts can address your concerns. Please don't reply until another expert responds or the site will cycle the question back to me.

Good luck with your MB!