[M73 wiring diagram](BMW_e38_750)

~6 wires are different between [Proteus 0.2](https://github.com/rusefi/rusefi/wiki/Hardware_Proteus_Wiring_v02) and [Proteus 0.3](https://github.com/rusefi/rusefi/wiki/Hardware_Proteus_Wiring_v03)


This HOWTO is focusing on M73 engine with stock ECU harness. 1998 stock ECU harness has two 134 pin connectors.

On my 1998 first set of 9+24+52+40+9=134 pins total is BLACK.

Second set of 9+24+52+40+9=134 pins total is GREY.

rusEFI uses six wire colors: black white red orange green blue.


# 9 pin plug #1 
| Pin  | type  | OEM color  | Description   | rusEFI color  |
|---|---|---|---|---|
|   |   |   |   |   |
|   |   |   |   |   |
|   |   |   |   |   |


# 24 pin plug #2
| Pin  | type  | OEM color  | Description   | rusEFI color  |
|---|---|---|---|---|
|   |   |   |   |   |

# 52 pin plug #3
| Pin  | type  | OEM color  | Description   | rusEFI color  |
|---|---|---|---|---|
|   |   |   |   |   |

# 40 pin plug #4
| Pin  | type  | OEM color  | Description   | rusEFI color  |
|---|---|---|---|---|
|  6|  IN   | |            start signal from ignition key |
| 17| OUT |BLK  |       engine speed output for gauge cluster
| 26| IN  |GRN/BLK| RED +12v hot in start & run
| 40| OUT |YEL/BRN |BRN starter enable
|   |   |   |   |   |

# 9 pin plug #5
| Pin  | type  | OEM color  | Description   | rusEFI color  |
|---|---|---|---|---|
|   |   |   |   |   |



# Proteus
* +12 from main relay
* x12 injectors
* CLT
* IAT




## Black 35 Pin 776231-1

|Pin Number|Name      | Type ID | Default function                   | rusEFI color | Destination |
| ---:|:------------- | ----- |:------------------------------------ |--------- | --- |
|  3  |**Lowside #1** | ls    | Injector #1                          | |
|  4  |**Lowside #3** | ls    | Injector #3                          | |
|  5  |**Lowside #5** | ls    | Injector #5                          | |
|  6  |**Lowside #6** | ls    | Injector #6                          | |
|  7  |**Lowside #7** | ls    | Injector #7                          | |
|  8  |**Lowside #9** | ls    | Injector #9                          | | 
|  9  |**Lowside #11**| ls    | Injector #11                         | |
| 10  |**Lowside #13**| ls    | low-side output: main relay          | Blue | Black plug #2 23/24 BRN/BLK |



## Black 23 Pin 776228-1
|Pin Number|Name   | Type ID | Default function                   |rusEFI color | OEM connector |
| ---:|:---------- | ----- |:------------------------------------ | :--------- | --- |
| 18  | +12 raw    | 12v   | ignition power / ECU power source    | Red |  Black plug #4 26/40 GRN/BLK |
| 19  | **GND**    | y     | Power GND                            | Black | Black plug #1 6/9 BRN |
| 23  | +12V mr    | 12v   | ETB/high-side power supply from main relay  | Red | Black #1 8/9 RED/BLU |