ECU Pinouts

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.

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
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
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.

Pin	Function	Pin	Function	Pin	Function	Image
1	Timing Control - to coil and O2 sensor	20		38
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.

Pin	Colour	Function	Pin	Colour	Function	Pin	Colour	Function	Image
1	BK	Timing Control - to coil and O2 sensor	20			38		ABS and OBC cutoff for Injectors
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.

Pin	Function	Pin	Function	Pin	Function	Image
1	Fuel pump relay output	29	ICV output	56	Ignition switch input
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