starfighter

I guess most of you know this, but being new to SL's ,
what's a SAM ?
Thanx

pmercury

iTrader: (2)

A SAM (Signal Acquisition Module) functions much as a network router does on a computer or communications network. It monitors input from various switches, controls, monitoring devices, and warning systems. When you push a button on, for example, your dashboard, the signal goes through a SAM before the device you are controlling responds. If there is something wrong with the device you are trying to operate, you will likely then get a warning, delivered through the SAM to the CAN (Controller Area Network) bus. The CAN bus will send the error message to the "error screen" you mentioned (the Multifunction Display, beneath your speedometer), or elsewhere in the instrument cluster. You may also get messages indicating normal operation, such as "car rising" when you raise it by the Airmatic system.





__________________________________________________ ______________________________
There are many choices for DAS/Xentry Diagnostics for MB.
Ensure you have the right information before getting one. There is too much misleading info.
I’m a forum member and programmer who’s learned the hard way. PM me if you have any questions.

bobterry99

A SAM is commonly referred to as a "signal acquisition module" -- and that is what I call it -- but Mercedes more accurately call it a "signal acquisition and actuation module" since it both receives signal inputs and controls ("actuates") components through its outputs.

All Mercedes models introduced since MY1996 are networked to simplify and reduce the amount of electrical wiring. Contrasting a vehicle which is networked with one that is not illustrates the role and importance of the network.

On a 1991 500SL there are three separate engine coolant temperature sensors located next to one another on the front of the engine. One is wired to the instrument cluster, another is wired to both the fuel injection and ignition controllers, and another is wired to the in-dash climate control unit. That might be forty feet of wiring in total for four independent circuits.

On a 2003 SL500 there is just one temperature sensor, and it is wired to the engine ECU. Since the instrument cluster and climate control are networked with the engine ECU, those units are able to receive the coolant temperature with no additional wiring. So in contrast to the 500SL's having four circuits, the SL500 has just one.

SAMs simplify wiring in the same way that the engine ECU does in the above example. But unlike the ECU, they do little more than read the state of inputs and report them to the network and control components wired to the their outputs in response to data received from various control modules. Consider control of the rear tail lamps.

The headlamp switch on the dash is wired to a SAM located in the engine compartment ("Driver-side SAM"). When you turn the lamps ON a SAM located behind the seats ("Rear SAM") responds by switching on the tail lamps wired to its outputs.

Frederick NL

There’s one in both fuse boxes under the bonnet (near the hinges) and one behind the right hand chair, under the small storage box. They’re all put to work, so to speak, by your electronic ignition switch (or ‘system’).
When strange gremlins start to harass you, like the seat belt stiffening up when you want your wipers to wipe, the EIS may very well be going south. Seemingly non-intertwined components may then be given awkward instructions.

Rudeney

Another function of the SAM is to control the exterior lighting. In the old days, all the lights were on fuses. On modern MBZ cars, the exterior lights are not fused. Instead, electronics in the SAM closely monitor current draw when a bulb is activated. If the SAM recognizes an over or under draw on the circuit, it shuts it off to protect the circuit. Also, in some cases, the SAM might even use a "substitute" bulb for that function. As an example, if a brake light is determined to be over or under the proper current draw, that circuit is shut down, but the SAM will instead use another bulb, such as the rear fog light, in place of that deactivated brake light.

starfighter

Thanx Fredrick NL
Most os the responses I received were from people on my "ignore list" so still didn't get what a SAM was.
From your reply sounds like a secondary control unit for each of three places.....?

H Swint

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Frederick NL

Starfighter, you are missing info you asked for, by ignoring contributors. They know more about it than I do.

bobterry99

That is something I only recently learned and is essential to know.

In an older vehicle with a non-working bulb which appeared okay you could remove the bulb and check for voltage on the bulb holder. If you do that on an R230 you will measure little or no voltage and would falsely conclude the problem was with the circuit powering the bulb.

The Driver-side SAM also has a bit of programming logic as well. There is no dedicated module for the alarm system as with older cars, and the R230 control software is all in the Driver-side SAM.

I presume he is "ignoring" me and pmercury. I won't speak to my own contribution but will comment that pmercury has a great deal to offer MBWorld if he chooses to.

Rudeney

Yep, checking bulb sockets with a voltmeter won't work on any modern MBZ with SAMs. The SAMs do have logic circuits for things like the alarm system. Another thing they do is interpret the dual fuel level sensors on saddle-style tanks to report a single value. It's simple logic, but imagine what it would have been like if we had this technology for the Apollo missions!