gf0761p3003mis

ME-SFI alternator interface function

Type gf · topic 07.61 · version 0101 · 2009-07-20

Applies to: ENGINE 272.9 (except 272.974) in MODEL 221.0 /1 (except 221.095 /195) as of model year 2009 /AEJ 08 ENGINE 273.9 in MODEL 216.3, 221.0 /1 as of model year 2009 / AEJ 08

Where it sits

Function group 1 Engine › 07 Mixture formation › 07.61 ME fuel injection/ ignition system — Series 216 (models 3**) · Series 221 (models 0**, 003, 022, 026, 028, 054, 056, 057, 070, 071, 073, 074, 077, 080, 082, 083, 084, 086, 087, 094, 1**, 103, 122, 126, 128, 154, 156, 157, 170, 171, 173, 174, 176, 177, 179, 180, 182, 183, 184, 186, 187, 194)

Also applies to engines/gearboxes: 272 911, 272 920, 272 921, 272 922, 272 923, 272 924, 272 939, 272 940, 272 941, 272 942, 272 943, 272 944, 272 945, 272 946, 272 947, 272 948, 272 949, 272 952, 272 960, 272 961, 272 963, 272 964, 272 965, 272 966, 272 967, 272 968, 272 969, 272 970, 272 971, 272 972, 272 973, 272 975, 272 977, 272 978, 272 979, 272 980, 272 982, 272 983, 272 984, 272 985, 272 988, 272 991, 273 9**

GF07.61-P-3003MIS

ME-SFI alternator interface function

25.6.09

ENGINE 272.9 (except 272.974) in MODEL 221.0 /1 (except 221.095 /195) as of model year 2009
/AEJ 08

ENGINE 273.9 in MODEL 216.3, 221.0 /1 as of model year 2009
/ AEJ 08

Function requirements for the alternator interface, general points

Circuit 87M ON (engine control ON)

Engine running

Alternator interface, general points

Through the alternator interface, messages are exchanged over the drive LIN (LIN C1) between the alternator (G2) and the ME-SFI [ME] control unit (N3/10), in order to regulate the alternator control response. For this purpose, the ME-SFI [ME] control unit reads the following sensor and signal:

- Crankshaft Hall sensor (B70), engine speed

- On-board electrical system battery voltage (G1) through "circuit 30"

Alternator interface function sequence

The ME-SFI [ME] control unit controls the alternator control response, for example, in order to reduce the regulation voltage (charging voltage) when the engine is at idle and the on-board electrical system battery is sufficiently charged This reduces engine load, thus lowering the fuel consumption and improving the exhaust gas emissions.

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The ME-SFI [ME] control unit controls the following functions:

- Switching on the alternator after engine start.

- Regulation of the alternator according to performance maps stored in the ME-SFI [ME] control unit. To do this, the control voltage is preset by the ME-SFI [ME] control unit.

- Adapting the control voltage with a delay in the event of frequent load changes at the alternator to stabilize the idling speed.

- Protecting the alternator against overheating.

- Generating of a "circuit 61 signal" (alternator in function).

- Reporting detected faults to the instrument cluster (A1) for actuation of the respective warning lamps and display messages.

The alternator performs continuous self-diagnosis and sends the results when requested to the ME-SFI [ME] control unit. The control unit compares the results with other signals (for example, engine rpm, on-board electrical system battery voltage, time since engine start) and thus detects any alternator faults.

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The following faults are identified:

- Short circuit or discontinuity at output "circuit 61" from ME-SFI [ME] control unit.

- Open circuit on alternator interface line (drive LIN) or interface driver fault in the ME-SFI [ME] control unit. For this type of fault, a regulation voltage of 13.45 up to 14.15 V is prescribed.

- Electrical and mechanical faults at alternator:
- controller or diodes defective
- stator interruption or short circuit
- excitation circuit open
- regulation voltage and charging current not reached
- regulation voltage too high
- cracked or loose poly-V belt

Diagnosis

To check the regulation voltage, the on-board electrical system battery must be loaded with a battery tester, as the regulation voltage can be significantly reduced when the on-board electrical system battery is under full or no load.

"Circuit 61 signal"

For alternators with an alternator interface, line
"circuit 61" is not needed. Using the information received by the ME-SFI [ME] control unit through the alternator interface, the "circuit 61 signal" is simulated in the ME-SFI [ME] control unit and sent through an output stage connected to ground (e.g. for the instrument cluster).

Electrical function schematic, alternator interface ME

Model 216

PE07.61-P-2755-97CAB

Model 221

PE07.61-P-2755-97SAB

Component description for ME-SFI [ME] control unit

N3/10 Engine 272

GF07.61-P-6000MIS

N3/10 Engine 273

GF07.61-P-6000MLS

Referenced documents