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451 SAM Unit Pin Out

Mod Description
SAM Unit 451 connections
Mod Details
PremiumNo Difficulty Mod ID821 Creditevilution For451 Fortwo Link Copy to Clipboard

So What Is The SAM Unit?

Essentially it is a fuse box with internal relays and a microprocessor that controls almost all of the electrical functions of the car. The processor is flashable so it can
be taught new tricks by way of a TAN code, these tricks include paddle gear shift, auto door locking, automatic gear change, day time running lights, cruise control etc.

What Does SAM Stand For?

Signal Acquisition & Actuation Module.

Where Is It?

It can be found at the top of the footwell, passenger side of a RHD smart city coupe/cabrio, driver’s side of a LHD smart city coupe/cabrio and the drivers side of a Roadster.

What Does It Look Like?

Just a plain boring black box with fuses pushed into the front. Although the SAM units all look the same, the 451 internals are slightly different.

What About The Bits We Can’t See?

The top side is where most of the wiring goes to, there are 10 connections and a positive input. All inputs are labelled. Each circuit has its own earth point around the car.

There Is Something Missing

Damn right, Relays. Most cars have relays in the fuse box, these control the horn, wipers, indicators, lights etc. The relays visible on the smart are for the fog light and heated seats.

How Does That Work Then?

No different except in this case the relays are actually inside the SAM unit.

Inside The SAM Unit

Unclip all the plastic clips around the outside

With the top off you see the main fuse connections

With it removed from the box you see the relays and connectors

The board is in 4 parts and is bent around on itself, you can see the back of the tracks look to become damaged. This is normal and ok. It’s just the carrier between the tracks.

PCB 1, 2 and 3 fold open and a flat plastic retainer can be removed.

PCB 4 is populated with the microprocessor…

…and many small relays

No User Serviceable Parts Inside

You can say that again, if you get water in this there is nothing that can be done. There is nothing you can take out or change, everything is soldered directly to the PCBs.

What About Microchips?

There are surprisingly few IC packages inside the SAM unit. The main one however is the Motorola MC9S12DG256C which is a 112 pin 16-bit device composed of standard on-chip peripherals including a 16-bit central processing unit (HCS12 CPU), 256K bytes of Flash EEPROM  and a whole load of other stuff that means very little to me. If you want to know more about this chip. Click here.

SAM connections

999cc Smart Fortwo
N11-1 Wire Colors Connection Fuse
1 Red Grey Blower Motor 4
2 Red Green MAF, O2 up, Glow Plug, EGR, Cam Solenoid, Pressure Valve 8
3 Red White Power Window Control Unit 3
4 N/C N/C N/C
5 Red Pink ESP Control Unit
6 Black Yellow  Alternator 1
7 Red Blue Radio 15
N11-2 Wire Colors Connection Fuse
1 Red White Additional Instruments pin1, rain/light sensor pin 1 12
2 Red Violet Cockpit Switch Group pin2 28
3 Violet White ECU pin72
4 Black Blue Heated Rear Window 28
5 Brown Earth
6 Red Black Soft Top Relay Close pin8 29
7 Blue AMT Control Unit pin17
8 Red Blue Soft Top Relay Open pin8 29
N11-3 Wire Colors Connection Fuse
1 Black Green Rear Wiper Motor pin2
2 Black Red Restraint Control, Yaw Sensor, ESP, Power Steering, Speedo 18
3 Black Yellow ECU pin65 19
4 Black Grey Stereo, Heated Seat Module, Wiper Stalk, Mirrors 20
5 Black Blue Cigarette lighter socket 21
6 Grey Yellow Left Low beam 22
7 Grey Violet Right Low beam 23
8 Red Yellow Stop Lamp Switch. Rear fog relay (light sensor only) 24
9 White Black Right High Beam 25
10 White Red Left High Beam 26
11 Red ECU pin80 (petrol) 27
N11-4 Wire Colors Connection Fuse
1 Red Black Ignition position 1
2 Red Blue AMT Module pin1 and 3 30
N11-5 Wire Colors Connection Fuse
3 Black Blue Front Wiper Motor pin3
4 Grey Yellow


Front Fog Lights

Day Time Running Lights

5 Yellow Front Wiper Motor pin4
6 Green Blue Rear Wiper Motor pin1 5
7 Grey Green Right Standing Lamp 6
8 Brown Grey Left Standing Lamp 7
9 Red Black Soft Top Relay, Interior Lamp 15
10 Red Yellow Fuel Injector Power 9
11 Red Grey Fuel Pump, ECU pin66,73, O2 down, Coil Packs 10
12 Blue Red CDI Control Module
N11-6 Wire Colors Connection Fuse
1 Violet Starter 1
2 Red Blue Diesel Fuel Pump
N11-7 Wire Colors Connection Fuse
1 Red White Power Steering Module 35
2 Red Green ESP Control Unit 34
3 Red Ignition Main Position 0
N11-8 Wire Colors Connection Fuse
2 Blue Black Boot Release Switch
3 Grey Brown Wiper Stalk pin4
4 Yellow White Right Door Rotary Switch
9 Blue Grey Front Wiper Motor pin2  2
10 Grey Blue Light Stalk pin2
12 Violet Green Microwave sensor pin 2, alarm siren pin 3
14 Green CAN Low ECU
15 Green White CAN High ECU
17 Yellow Wiper Stalk pin5
18 White Green Left Door Central Locking Switch
19 Yellow Black Left Door Rotary Switch
21 Brown/White Heated mirror relay pin 4
29  Red Violet Cockpit ambient illumination (lighting)
30 Grey White Rear Soft Top Microswitch
31 Violet Blue Cockpit Switches pin12 Hazards
32 Yellow Blue Soft Top Microswitch
33 Violet White Roof Cassette Microswitch
35 Pink Blue Soft Top Power Switch
36 Pink Yellow Boot Handle Switch
38 Grey Black Ignition Position 2
39 Green CAN Low to Speedo
40 Green White CAN High to Speedo
N11-9 Wire Colors Connection Fuse
1 Black White Left Headlight Indicator
2 Blue Red Boot Opening Solenoid 31
3 Grey White Transponder Coil 2 (immobiliser antenna)
4 Brown Blue Front Interior Lamp
6 Yellow Grey Soft Top Relay pin4
8 Blue Cockpit Switches pin13 Tow Sensor
9 Yellow Light Stalk pin5
11 Black Green Right Headlight Indicator
12 Pink Cockpit Switches pin10 Central Locking
13 Blue Yellow Cockpit Switches pin8 Front Foglights
14 Violet Blue Dash Top Pods, rain/light sensor pin 2 (LIN Bus)
16 Black Blue Cockpit Switches pin11 Unlock
17 Green Blue Wiper Stalk pin7
18 Yellow Blue Rear Fog Lamp Relay pin4 (light sensor only)
20 Violet White Transponder Coil 1 (immobiliser antenna)
21 Brown Black Transponder Coil 3 (immobiliser antenna)
22 Green Black Luggage Carrier/Base Rack
23 Grey Footwell Ambient Illumination (lighting)
24 Red Black Transponder Coil 4 (immobiliser antenna)
30 Pink Black Horn Button
33 White Black Heater Air Conditioning Unit
34 Yellow Red Light Stalk pin
35 Violet Green Light Stalk pin4
36 Green Red Wiper Stalk pin1
37 Grey Cockpit Switches pin9 Rear Fog Light (light sensor only)
38 White Red Light Stalk pin6
39 Black Brown Light Stalk pin7
40 Red Green Wiper Stalk pin10
N11-10 Wire Colors Connection Fuse
1 Brown Earth
2 White Aircon Compressor
3 Red Blue Coolant Radiator Fan
4 Grey Yellow Central Locking Door Open 31
5 Pink Central Locking Door Closed 31
6 Blue Horn 31
7 Yellow Intercooler fan 14
N11-11 Wire Colors Connection Fuse
1 12 Volt SAM Power In 33