BMW MS41 / MS41.3 Wiring Diagrams
Updated: 2 hours ago
Use this page as a quick reference for factory MS41 wiring and the inputs/outputs commonly repurposed for MS41.3.
Factory wire colors are listed where confirmed in the official BMW E36 wiring diagram.
The official BMW E36 wiring diagram will be attached at the bottom of this page for download and reference.
Factory Tuning-Related Pins
Pin 7
Function: MAF Ground
Color: SW — Black
Pin 8
Function: MAF Signal
Color: GE — Yellow
Pin 10
Function: Coolant Temperature Signal
Color: BR/RT — Brown/Red
Pin 11
Function: Fuel Tank Pressure Sensor
Color: Verify on vehicle harness
Pin 12
Function: Throttle Position Signal
Color: SW — Black
Pin 14
Function: Intake Air Temperature
Color: GR — Gray
Pin 44
Function: 5V Sensor Supply
Color: RT/GN — Red/Green
Pin 68
Function: Charcoal / Carbon Canister Purge Valve
Color: BR — Brown
Pin 75
Function: Front O2 Sensor 1 Signal
Color: GE — Yellow
Pin 76
Function: Front O2 Sensor 2 Signal
Color: GE — Yellow
Pin 77
Function: Rear O2 Sensor 1 Signal
Color: Verify on vehicle harness
Pin 78
Function: Rear O2 Sensor 2 Signal
Color: Verify on vehicle harness
Pin 80
Function: ASC Input
Color: WS/GN — White/Green
Pin 81
Function: ASC Input
Color: WS/GR — White/Gray
Pin 82
Function: ASC Input
Color: WS/SW — White/Black
Pin 88
Function: Diagnostic Data Line
Color: WS/VI — White/Violet
Nissan / Hitachi MAF to BMW MS41 Wiring
Nissan / Hitachi 6-Pin Connector
Pin 1 — Blank
N/C
Pin 2 — +12V Power
Hitachi wire: Red
BMW wire: Black/Yellow
Pin 3 — MAF Ground
Hitachi wire: Black
BMW wire: Brown/Orange
Pin 4 — MAF Signal
Hitachi wire: White
BMW wire: Yellow
MS41 ECU: Pin 8
Pin 5 — IAT Signal
Hitachi wire: Green
BMW wire: White
Pin 6 — IAT Ground
Hitachi wire: Yellow
BMW wire: Brown
The MAF transfer table must also be calibrated for the specific Hitachi MAF being used.
MS41.3 Sensor Inputs
Pin 75
Original: Front O2 Sensor
Factory Color: GE — Yellow
MS41.3 Use: Wideband O2
Pin 76
Original: Front O2 Sensor
Factory Color: GE — Yellow
MS41.3 Use: MAP Sensor
Pin 77
Original: Rear O2 Sensor
Factory Color: Verify on vehicle harness
MS41.3 Use: Oil Pressure
Pin 78
Original: Rear O2 Sensor
Factory Color: Verify on vehicle harness
MS41.3 Use: Fuel Pressure
Pin 11
Original: Fuel Tank Pressure SensorFactory Color: Verify on vehicle harness
MS41.3 Use: Flex Fuel
For a frequency-output ethanol sensor:
Flex Sensor → Signal Converter → 0–5V Output → ECU Pin 11
MS41.3 Switch Inputs
Pin 80
Original: ASCFactory Color: WS/GN — White/Green
MS41.3 Use: Boost Map Switch
Pin 81
Original: ASC
Factory Color: WS/GR — White/Gray
MS41.3 Use: Rolling Anti-Lag / Ignition Retard
Pin 82
Original: ASCFactory Color: WS/SW — White/Black
MS41.3 Use: Flat-Foot Shift
MS41.3 Boost Control
Pin 68
Original: Charcoal / Carbon Canister Purge Valve
Factory Color: BR — Brown
MS41.3 Use: Boost Control Solenoid
FergZ Garage Quick Reference
75 — GE / Yellow → Wideband O2
76 — GE / Yellow → MAP
77 → Oil Pressure
78 → Fuel Pressure
11 → Flex Fuel
80 — WS/GN → Boost Map Switch
81 — WS/GR → Rolling Anti-Lag
82 — WS/SW → Flat-Foot Shift
68 — BR / Brown → Boost Control Solenoid
Important
Do not identify a circuit by wire color alone.
Always confirm:
ECU pin number
Connector location
Original function
Wire color
Sensor signal type
MS41.3 configuration
before cutting or repurposing factory wiring.
Official BMW E36 Wiring Diagram
The official BMW E36 Electrical Troubleshooting Manual for the 328i will be attached below.
Attached File
Official BMW E36 328i Wiring Diagram
BMW Wire Color Key
BL = Blue
BR = Brown
GE = Yellow
GN = Green
GR = Gray
OR = Orange
RS = Pink
RT = Red
SW = Black
VI = Violet
WS = White
TR = Transparent
For striped wires:
WS/GN = White with Green stripe
WS/GR = White with Gray stripe
WS/SW = White with Black stripe
WS/VI = White with Violet stripe
RT/WS = Red with White stripe
BR/RT = Brown with Red stripe
RT/GN = Red with Green stripe
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