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M104 HFM Wiring diagrams from '93-'95 E320

 

Here are some M104 HFM wiring diagrams for your reference and they only apply to 1993-1995 300E/E320. They were scanned from original MB literature ETM's and broken into .jpg images.  Please note that the original diagrams unfold and can stretch over 3 feet wide, so you need to print each image out and tape them together to make a complete diagram. You will need to resize them in order to print them out, this is for the best possible print quality. They were scanned on the highest resolution my cheapo scanner has to offer, so it may take a few seconds to load.

For a brief overview of how the HFM system is wired, the HFM control module has 2 connectors: 1 that goes to the engine assembly (fuel injectors/coils/etc..) and 1 that goes to the chassis (O2 sensors/fuses/fuel pumps/ignition switch/etc..). The 2 connectors are split into 2 separate diagrams: diagram 1 is for the chassis, diagram 2 is for the engine. There is also a diagram for the CC/ISC (cruise control/idle speed control) module, which is what controls the throttle actuator. It has only one connector and on the E320 it sits on the passenger false floor (where your front passenger's feet would be). The last diagram is for the diagnostic module (OBDI), which is only used for self-checks and turning on the check engine light. On the E320 it sits behind the driver's underdash trim panel and looks much like a MAS relay from the early 90's with a twist-lock top.

 

Wiring diagram, Engine 104 with HFM fuel injection/ignition, Diagram 1

Diagram page #1     Diagram page #2     Diagram page #3     Diagram page #4

 

Wiring diagram, Engine 104 with HFM fuel injection/ignition, Diagram 2

Diagram page #1     Diagram page #2     Diagram page #3     Diagram page #4     Diagram page #5

 

Wiring Diagram, Cruise Control (CC)/Idle Speed Control (ISC), Engine 104 w/HFM

Diagram page #1     Diagram page #2     Diagram page #3     Diagram page #4     Diagram page #5

 

Wiring Diagram, Diagnostic Module, Engine 104 w/HFM

Diagram page #1     Diagram page #2     Diagram page #3

 

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