ECU Pinouts

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Motronic 1.3 ECU plug
Motronic 1.3 ECU plug

The ECU is the very heart of your engine management system. Almost everything under the bonnet, and a lot of the stuff inside the car, connects to it in some way.

When things start going wrong, it's essential to check that signals are getting to or coming from the ECU, and that means testing the wiring. To help you identify what goes where, here are the pinouts for each generation of E30 ECU.

Contents

Jetronic

Jetronic's primitive management system only controlled fuelling, so the ECU is little more than an injection control unit. The control model uses a 25-pin plug, with Pin 1 at the cable end. Note that the ECU connector is accompanied by the C104, a small 3-pin plug that provides data for the Instruments.

Pin Colour Function Pin Colour Function Image
1 GN Engine Speed input (RPM) 14 Image:JetronicPins.jpg
2 BR/BU Closed Throttle input 15
3 BR/BK WOT input 16
4 BK/YL Cranking signal 17
5 BR Ground 18 BU/BR Cancels deceleration fuel shutoff when A/C clutch is on
6 GN/RD Engine Load Output to Vacuum Control 19
7 GY/YL AFM input 20 GN O2 Sensor input
8 GN/VI AFM reference output 21
9 RD/WT Power input 22 WT/GN Fuel rate to Diagnostic plug
10 BR/RD Coolant Temp input 23
11 WT Barometric Pressure input 24
12 BR/YL Injectors and Econometer 25
13 BR Ground
C104
1 BL/BU Tachometer 2
3 WT Econometer

Motronic 1.0

The Motronic 1.0 ECU employs a 35-pin plug to connect to all the engine bay components.

Pin Function Pin Function Image
1 Ignition coil output 19 Ground Image:Motronic1_0Pins.jpg
2 Idle switch 20 Main relay
3 WOT switch 21 Tachometer
4 Cranking signal 22 AFM Temp sensor
5 Ground/Crank PosS Gnd 23 Inlet Air Temp/Crank SpS Gnd
6 AFM ground 24 O2 sensor signal *
7 AFM signal 25 Crank position sensor 1
8 Crank speed sensor 1 26 Crank position sensor 2
9 AFM supply 27 Crank speed sensor 2
10 Auto only special 28 Water Pressure switch
11 Fuel consumption gauge 29 A/C switch (if installed)
12 30 +Inlet Air Temp
13 Water Temp 31
14 Injector output cyl 3&4 32
15 Injector output cyl 1&2 33 ICV pulse
16 Ground 34 ICV pulse
17 Ground 35 Injector ground
18

Motronic 1.1

Motronic 1.1 uses a much chunkier plug, fitting 55 pins into three rows. Unlike Jetronic and Motronic 1.0, pin 1 is now at the end furthest from the cable.

PinFunctionPinFunctionPinFunctionImage
1 Timing Control - to coil and O2 sensor 20 38 Image:Motronic1_3Pins.jpg
2 Ground 21 39 Programming voltage - Diagnostic Plug
3 Fuel pump relay control 22 Idle speed control 40 A/C on input
4 Idle speed control 23 O2 sensor heater 41
5 Evaporative purge valve 24 Ground 42 Park/ neutral input (auto only)
6 Engine Speed output- to instrument cluster 25 43
7 AFM input - pin 2 26 AFM common- ground pin 4 44 AFM air inlet temp- pin 1
8 Cylinder ID sensor input 27 Start input- to ignition switch and coil 45 Coolant Temp input
9 28 O2 input 46
10 O2 sensor ground 29 47 Engine speed input
11 30 48 Engine speed input
12 AFM reference output- pin 3 31 Cylinder ID sensor input 49
13 RXO - diagnostic plug 32 Econometer 50
14 Ground 33 51
15 Check engine light - to cluster 34 52 Closed throttle input - pin 1
16 Injectors 1,3,5 35 53 WOT input - pin 3

Note: TPS pin 2 is ground

17 Injectors 2,4,6 36 Main relay 54
18 Power input main relay 37 Power input - to main relay 55 TXD - diagnostic plug
19 Ground

Motronic 1.3

Motronic 1.3 uses the same engine loom as Motronic 1.1, and therefore the 55-pin plug remains the same. However, the small differences that crept into production during the lifetime of Motronic 1.3 mean that a few extra wires are in place, to control features such as ABS.

PinColourFunctionPinColourFunctionPinColourFunctionImage
1 BK Timing Control - to coil and O2 sensor 20 38 ABS and OBC cutoff for Injectors Image:Motronic1_3Pins.jpg
2 BR Ground 21 39 GN/BU Programming voltage - Diagnostic Plug
3 BR/GN Fuel pump relay control 22 WT/GN Idle speed Close control 40 BK/GY A/C low pressure cutoff
4 WT/YL Idle speed control 23 BR/GR O2 sensor heater 41 VI/GY A/C On input
5 BR Evaporative purge valve 24 BR Ground 42 RD/BU Park/ neutral input (auto only)
6 BK Tachometer 25 43
7 GY/YL AFM input - pin 2 26 GY/BU AFM common- ground pin 4 44 GY/VI AFM air inlet temp- pin 1
8 BL Cylinder ID sensor input 27 GN Start input- to ignition switch and coil from OBC 45 BR/RD Coolant Temp input
9 28 BK O2 input 46
10 YL O2 sensor ground 29 BK/WT Vehicle Speed input from instrument cluster 47 BL Engine speed input
11 30 48 YL Engine speed input
12 GY/WT AFM reference output- pin 3 31 YL Cylinder ID sensor input 49
13 WT/YL RXO - diagnostic plug 32 WT/BL Econometer 50 ABS Deceleration Fuel Cut-Off Overide
14 BR Injector Ground 33 51 Auto Kick-Down Switch input
15 GY Check engine light - to cluster 34 52 BR/BL Closed throttle input - pin 1
16 BR/WT Injectors 1,3,5 35 53 BR/BL WOT input - pin 3

Note: TPS pin 2 is ground

17 BR/YL Injectors 2,4,6 36 BR Main relay output 54 Automatic Transmission Torque Converter Lock-up Switch
18 RD Constant 12V from Battery 37 RD/BU Switched power from main relay 55 WT/VI TXD - diagnostic plug
19 BR/OR Main Ground

Motronic 1.7

The Motronic 1.7 system was exclusive to the 318iS before being fitted to the E36. For all you 16Vers, this table was taken from the E36 handbook; hopefully it will prove to be applicable to the E30 as well.

PinFunctionPinFunctionPinFunctionImage
1 Fuel pump relay output 29 ICV output 56 Ignition switch input Image:Motronic1_7Pins.jpg
2 30 57-58
3 Injectors 2 and 4 31 59 TPS and VAF 5V reference
4 32 Injectors 1 and 3 60 Data link connector input
5 33 61-63
6 Injector ground 34 Ground 64 Transmission control input (EGS)
7 35 65 Automatic transmission range switch
8 Check engine light 36 Evaporative purge valve 66
9 37 O2 Sensor heater 67 Crank Position Sensor input
10 38 68 Crank Position Sensor output
11 Transmission control input (EGS) - DKV sensor 39 69
12 TPS input 40 70 O2 Sensor input
13 41 Volume Air Flow sensor input 71 O2 Sensor ground
14 Volume Air Flow sensor input 42 Cylinders 3-4 knock sensor input 72
15 Cylinders 1-2 knock sensor input 43 Ground for temp, knock and throttle sensors 73 Vehicle Speed output
16 Cylinder ID sensor input 44 Cylinder ID sensor input 74 Crankshaft Speed signal TD
17 Fuel consumption for Instruments 45 75
18 Intake air resonance takeover valve 46 76 Volume Air Flow sensor input
19 47 77 Volume Air Flow sensor input
20 48 A/C compressor cutout 78 Coolant Temp input
21 49 79-80
22 50 81 OBC code protection
23 51 Cylinder 4 Ignition Coil 82-84
24 Cylinder 3 Ignition Coil 52 Cylinder 2 Ignition Coil 85 A/C pressure switch input
25 Cylinder 1 Ignition Coil 53 86 A/C switch
26 Battery Voltage input 54 Engine control relay output pin 87a 87 Data Link Connector RxD
27 Engine control relay output pin 85 55 Ignition Ground 88 Data Link Connector TxD
28 Ground