Bmw e23 ecu

**Cambridge** · 06-30-2020, 08:09 PM

Bosch Motronic M1.0 Adaptive, part no. 0 261 200 059

Table of Integrated Circuits and Transistors

board label	device label	substitution	function
S100	F12438-03 or InterDesign 8423 2438-03 or InterDesign 8504 2438-03		custom
S300	L4705CV		Much like LM7805 volt regulator but with protection for +/- 80 V transients, reverse polarity and low dropout of just 0.5v
S700	B57306	80C52	Intel 8051 family microprocessor
S701	27C32		CMOS EPROM 4K x 8 24 pin
S702	B57356 or B57317	74LS373N	Octal D Latch 20 pin
S703	B57120	ADC0809	8 bit 8 channel multiplexed Analog to Digital Converter
S704	CD4049UBEX	CD4049UBE	Inverter CMOS TTL Level Translator
S705	B57318	74LS02	Positive NOR gate
S720	B57348	C2101 or 5101L-1 or AM9101	256 x 4 static RAM
S800	CA139EX	LM339N	Quad Comparator
S890	CA139EX or CE 01 0986 3054	LM339N	Quad Comparator
T200	BC546B
T320	BC558B
T321	BC558B
T322	BC558B
T401	BC546B
T420	RBDT95 or BDT95	BD911	NPN Power
T431	SR52	BSR52	NPN Darlington
T480	ON588	BDX53C
T500	BC546B
T501	BC546B
T502	BC548C
T503	ON946	BDW46G
T504	Bosch 1012	BU941	NPN Power Darlington Ignition Coil Driver
T505	BC548C
T560	ON588	BDX53C
T561	ON588	BDX53C
T730	BC546B
T820	ON588	BDX53C

I've rebuilt a few Bosch 059 Motronic ECUs. I find most of the parts by the device label from standard parts houses such as DigiKey, Mouser, Newark, Jameco etc. otherwise Amazon, or even EBay. Otherwise, I use a part listed in the substitution column. I've developed this substitution list over the years as some of the original parts become unavailable. Many of the chips and transistors are fairly conventional parts from the 1980's. Of course, the one exception is the S701 part which is a special custom chip used for collecting and normalizing the signal from the two flywheel reference sensors. Probably easiest way to source this chip is to cannibalize a junk Bosch Motronic ECU from the same era. Fortunately I've never seen this chip go bad.

The unit is fairly rugged. Usually just simply reflowing cracked solder joints on the heavier parts restores to good working order. The weight of the heavier parts tends to fatigue the solder joints over the years and create micro-cracks. A good example is part T504, the Bosch 1012 ignition coil driver. Symptom includes car running perfect for days then just suddenly stops - no spark. A hard whack on the ECU cover temporarily closes the cracked solder joint and the car runs fine again ... for a while.

In some cases the 1012 itself needs replacement. Since the 1012 is a custom Bosch part and is no longer available, the BU941 or BU941Z is an excellent replacement with superior specs. The Porsche DIY folks have been using them as replacements for years in their Motronic ECUs. Of course, the BU941 and BU941Z have only two pins and case compared to the Bosch 1012's 3 pins and case. However, note that the "third" lead from the Bosch 1012 is the same as case, so to use a BU941 or BU941Z simply solder a wire directly to the case to get that third lead. Scratch the nickel plating to get to the "solderable" metal below (brass/copper/whatever) and attach the wire.

I've also noticed that S703 failures can introduce weird performance issues. This is the 8 channel A to D converter. It is used for all the sensors feeding into the ECU. Symptoms include car idling just fine but when accelerating past 2500 RPM engine becomes dramatically erratic.

Another related problem source, although not strictly speaking the ECU, is the main relay. It's mounted high on the firewall on the passenger (RH) side. Symptoms include unexpected transmission shifts and ignition cutouts or stumbles after hitting a bump or rough pavement. This can usually be fixed by removing the relay, temporarily opening its cover, and reflowing the solder joints (also good to clean the relay connections and socket). This relay feeds primary power to the Transmission Control Unit (TCU) and the Engine Control Unit (ECU). And when a crack in the main really solder joint intermittently opens (due to a bump in the road) it interrupts power to both control units forcing them to cold reboot.

Motronic 35 pin connector

pin	function
1	timing control (ignition coil output)
2	closed throttle input (TPS idle switch)
3	full load input (TPS wide open throttle switch and TCU full load output pin 31)
4	start input (cranking signal. grounded except in start. Otherwise car will run rich)
5	ground (and shield for crank position sensor cable)
6	common (AFM ground)
7	air flow input (AFM signal)
8	engine speed input (crank speed sensor 1)
9	reference output (AFM supply)
10	shift input (from transmission control unit shift output pin 24)
11	fuel rate output (MPG fuel consumption gauge)
12	diagnostic connector pin 5
13	engine temperature input (coolant temp)
14	fuel injectors control 1, 2 and 3
15	fuel injectors control 4, 5 and 6
16	ground
17	ground
18	continuous power
19	ground
20	fuel pump relay control
21	engine speed output (instrument tachometer input and TCU tach input pin 21)
22	air inlet temperature (AFM temp sense)
23	shield (for oxygen sensor and engine speed sensor cable)
24	oxygen sensor input
25	reference point input (crank position sensor 1)
26	reference point input (crank position sensor 2)
27	engine speed input (crank speed sensor 2)
28	transmission input (automatic transmission range switch)
29	A/C “on” input
30	not used
31	oxygen sensor heater relay
32	not used
33	extend control (ICV pulse)
34	retract control (ICV pulse)
35	ignition power

**BMWCCA** · 07-01-2020, 06:19 AM

Nice work , I started reverse engineering the CDP 1802 processor with 745i source code years ago but after about 25 pages of logic flow diagrams project stopped lol

**Hit Man X** · 07-01-2020, 02:00 PM

I have a known sub for the 1012 in an 745i ECU and 008 733i ECU. Works great.

List is great, I have an inop 013 that was fully gone through and still kaput. Thinking a dead IC, so going to start swapping from junk units to build a good one.

**8991XJ** · 07-01-2020, 03:46 PM

"Known parts houses Ebay and amazon." That would get you expelled from a vintage audio site where counterfeits are to be avoided. Mouser and Digikey are the Known Parts Houses.

but it is nice to see a list of replacement parts for these ECUs. I've got an 059 in the 5 and an 061 in the 7 but need to rebuild the alarm box in the 7 to get that to work again.