Bmw E30 Motronic Wiring Diagram

Where and how to access ECU: I have tried to illustrate where and how to access the ECU, it is in the glove box compartment. To access it open your glove box and undo the two screws holding the plastic cover that is at the "ceiling" of the glove box compartment, under there you will find the ECU and the Connector.

Interesting fact: The 153 Motronic 1.1 ECU is directly swappable (without any modification or otherwise) with all motronic 1.3 ECU's. The Grey label 173 is the most popular of the 1.3 ecu's, mainly because of its availability. Generally speaking there is no advantages to running one 1.3 ECU over another. The differences between the 1.1 and 1.3 apart from software updates is that the 1.3 uses only 1 board within the ECU whereas the 1.1 uses two boards. Having less boards means less failure points. Some people have claimed to have better idle with the 1.3 ECU's although I haven't noticed such improvements. As I have covered in another article the main benefit to the 1.3 ECU's is that they are able to store engine fault codes and you do not need a scanner to access them, all you need to do is preform a stomp test. Click "this" to access the stomp test page.

The Motronic 1.0 ECU (325, 325e)

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 (325i, 325is, 325ix) Green label 153 ECU.

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 3Note: 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 (325i, 325is, 325ix) later model 173 grey label ECU and others (351, 380, 382, 524, 525, 526)

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 frominstrument 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 3Note: 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 fromBattery	37	RD/BU	Switched power from main relay	55	WT/VI	TXD – diagnostic plug
19	BR/OR	Main Ground

ECU electrical tests (at the connector)

35 pin (325, 325e)

55pin (325i, 325is, 325ix)

List of 6 cylinder E30 ECU's

325i/is/iX
E30
M20/B25 (170hp)
87-91
0 261 200 153
Bosch Motronic M1.1

325i/is/iX
E30
M20/B25 (170hp)
87-91
0 261 200 173
Bosch Motronic M1.3

325i/is/iX
E30
M20/B25 (170hp)
87-91
0 261 200 351
Bosch Motronic M1.3

325i/is/iX
E30
M20/B25 (170hp)
87-91
0 261 200 380
Bosch Motronic M1.3

325i/is/iX
E30
M20/B25 (170hp)
87-91
0 261 200 382
Bosch Motronic M1.3

325i/is/iX
E30
M20/B25 (170hp)
87-91
0 261 200 524
Bosch Motronic M1.3

325i/is/iX
E30
M20/B25 (170hp)
87-91
0 261 200 525
Bosch Motronic M1.3

325i/is/iX
E30
M20/B25 (170hp)
87-91
0 261 200 526
Bosch Motronic M1.3

325e/es
E30
M20/B27 (122hp)
9/84-12/86
0 261 200 027
Bosch Motronic Basic M1.0

325e/es
E30
M20/B27 (127hp)
1/87-9/87
0 261 200 154
Bosch Motronic M1.1

This entry was posted on October 27, 2012 at 9:14 pm and is filed under Do it Yourself. You can follow any responses to this entry through the RSS 2.0 feed.