Voltage supply of ME-SFI control unit, function

P07.61-2776-01

Model 215, 220

K40/7kL Starter relay (right fuse and relay module)

K40/7kN Air pump relay (right fuse and relay module)

K40/8kV Motronic relay, circuit 87 (engine fuse and relay box)

K40/8kW Charge air relay (engine fuse and relay box)

N3/10 ME-SFI control unit

P47.20-2192-01

Model 215, 220 with engine 275.980

K40/8 Engine fuse and relay box

K40/8kV Motronic relay (motor electronics control unit)

K40/8kW Charge air relay (charge air cooling circulation pump)

K40/8kX Intank fuel pump relay

P07.61-2880-06

Model 230

F33 Rear prefuse box

(Fuses 200 A and 60 A screwed on to reverse side)

N3/10 ME-SFI control unit

K40/4 Passenger-side fuse and relay module

K40/4f43 Fuse 43
(circuit 87 engine 1,
connector sleeve Z7/35)

K40/4f44 Fuse 44
(circuit 87 engine 2,
connector sleeve Z7/36)

K40/4kK Motor electronics relay and chassis (plug position K)

K40/4kL Starter relay (plug position L)

K40/4kM Circuit 30z relay (AMG)

K40/4kM Backup relay

K40/4kO Air pump relay or reserve (plug position O)

P07.61-2766-06

Model 240

B37 Accelerator pedal sensor

f21 Fuse 21 (circuit 87 for relayN10/1kI,
circuit 30z for ME-SFI control unit)

F34 Interior fuse box

K6 Starter relay

N3/10 ME-SFI control unit

N10/1 Driver-side SAM control unit with fuse and relay module

N10/1f43 Fuse 43
(circuit 87 engine 1, ECI ignition system, connector sleeve Z7/35)

N10/1f44 Fuse 44
(circuit 87 engine 2,
connector sleeve Z7/36)

N10/1kI Circuit 87 relay, engine

Voltage supply

The ME-SFI control unit is supplied with voltage at circuits 87 and 30 as follows (fused/unfused):

Model 215, 220 from right front fuse and relay module (K40/7)

Model 230 from passenger-side fuse and relay module (K40/4)

Model 240 from driver-side SAM control unit with fuse and relay module (N10/1)

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Ground connections of output stages

Several ground connections and the ground of the electronics are attached connected lose to the ME-SFI control unit (major assemblies compartment partition, wheelhouse or body).

The ME-SFI control unit features a short-circuit protection as well as a reversed polarity protection in the operating voltage section.

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In certain cases voltage is supplied through several pins connected in parallel by means of bridges to relief the electrical connectors.

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If the signal sent by the EIS control unit (N73)

"Circuit 15 Fused On" is read in by the ME-SFI control unit (N3/10), the ground for the engine main relay is transmitted by actuation of a transistor. Once the engine main relay has closed the power contact, voltage flows through it from

circuit 30 via two fuses as circuit 87 M to the ME-SFI control unit and the engine control. For the purpose of assigning consumers/components to the two 20 A fuses, a distinction is made as to which consumers/components of the motor electronics are required or non-required for engine operation.

If the ME-SFI control unit receives the signal "circuit 15 fused OFF" from the EIS control unit, the computer run-on time is started. Once this run-on time has elapsed, the engine main relay is switched off and the ME-SFI control unit is thus isolated from the electrical system.

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Voltage supply: refer to Wiring Diagrams, Group 54.