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Fuel lniection 1 
Table b. Siemens MS 41.1 ECM pin assignments  (continued) 
Pin 
lSiqnal 1 Componentlfunction / Notes I - I I 
40 1 ground  /Crankshaft position sensor /crankshaft position sensor control I - I I 
41 1 ground /Camshaft position sensor (CMP) /shielding for CMP sensor I - I I 
42 1 ground I~hrottie position sensor (TPS) /TPS ground 
43 
44 
45 
46 
47 
48 
49 
50 
51  ground 
output 
output 
output 
outout 
I I I 
input 
52  53 
54 
55 
56  57 
58 
59 
60 
61 
62 
63 
64 
65 
66  Camshaft position sensor (CMP) 
Throttle  position sensor (TPS) 
Throttle  position sensor (traction control) 
Instrument cluster 
Not  used 
Crankshaft position sensor (Hall effect) 
I~ot used 
I I I 
Fuel pump  relay control  Camshaft 
positionlrpm sensor control 
Voltage 
supply to  TPS  (5 vdc) 
ABSIASC module 
Instrument cluster, fuel reserve signal 
Crankshaft position sensor control 
Power  supply  (terminal  15) 
Not  used 
Not  used 
output  input 
ground 
ground 
output 
input 
output 
inputloutput 
ground 
output 
input 
input 
input 
I I 
Battery voltage with  key on or engine running 
Oxygen sensor signal ground 
67 
Idle speed control valve 
Power  supply 
Oxygen sensor heater  (no. 2 in front catalytic 
converter) 
Ignition circuit 
Knock  sensor 
(cyl. 1-3) 
Knock  sensor  (cyl. 1-3) 
Knock  sensor 
(cyl4-6) 
Data linic connector (TxD) 
Oxygen sensor heater  (no. 2 behind catalytic 
converter) 
Secondary air injection 
Knock  sensor  (cyl. 4-6) 
Camshaft 
positionlrpm sensor 
Camshaft 
positionlrpm sensor 
Not  used 
Pulse ground with engine  at normal temperature with 
varying engine load 
68  Pulsed ground-close signal (see 
pin 26) 
Battery voltage  from main relay (terminal 87) 
Oxygen sensor heater ground 
Ignition circuit monitoring signal 
Knock  sensor 
Knock sensor signal 
Knock  sensor 
Diagnostic 
TxD (transmit) signal  to pin 18  in data  link 
connector 
Oxygen sensor heater ground 
Secondary air injection control 
valve 
Knocic sensor signal 
Camshaft positionlrpm sensor control 
Camshaft 
positionlrpm sensor control 
ground  Oxygen sensor 
(no. 
1 in front  of catalytic 
converter) 
output  Evaporative purge 
valve control    

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/Fuel injection 
Table  b. Siemens  MS 41.1 ECM pin assignments (continued) 
85 
86 
87 
88 CAN-Bus low 
CAN-Bus  high 
Power supply 
Diagnostic connector 
(TxD) 
inputloutput 
inpuWoutput 
input 
input output  Automatic transmission control module (AGS) 
Automatic transmission control module (AGS) 
Battery voltage from main relay terminal 87 
Diagnostic TxD signal  to pin 17 in data link connector    

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- -. 
Fuel Injection 
SIEMENS MIS 42.0 AND 43.0 
When system faults  are detected, a  diagnostic trouble  code 
(DTC)  is stored  in the  engine  control module  (ECM). The MIL 
also illuminates 
if an emissions-related  fault  is detected. 
When  faults arise,  or 
if the malfunction indicator lamp  (MIL) is 
illuminated, begin  troubleshooting by connecting  BMW ser- 
vice  tester 
DISplus, MoDiC, GTI or equivalent scan tool.  The 
capabilities  of OBD 
II software has  the potential  to save hours 
of  diagnostic  time and to help avoid incorrect component re- 
placement  and possible  damage to system  components. 
CAUTION- 
* The tests  in this section  may set fault  codes (DTCs) in tlie 
ECM  and illuminate the  MIL. After all testing is completed, 
access  and clear DTC  fault 
memory using an OBD I/ or 
BMW  compatible scan  tool. See 
OBD On-Board  Diag- 
nostics. 
Only  use a 
dgital multimeter  for  electrical tests. 
Relay  positions  can vary.  Be sure  to confirm 
relayposi- 
tion by  identifying the  wiring in the socket  using the wir- 
ing  diagrams found in 
ELE Electrical  Wiring 
Diagrams. 
NOTE- 
- OBD I1 fault  memory. (including  an illuminated MIL! can 
only  be reset  using  the special scan  tool. Removing  the 
connector from the  ECM or disconnecting  the battery will 
not erase the  fault memory. 
The  BMW-dedicated  20-pin diagnostic 
linlc connector 
(DLC)  is in  the  right  rear of the engine  compartment  The 
20-pin DLC  is discontinued  on models after 
6/2000. 
The 1 &pin OBD I1 diagnostic connector (arrow) is located 
inside the  car on the lower left  dash panel. 
The  MS 
42.0 and MS 43.0 systems manage  the following 
functions. 
- Air: 
Idle speed  valve 
Electronic  throttle 
Hot  film  mass  air flow  (MAF)  sensor 
Resonance-turbulence  intake control 
- Fuel: 
* Fuel  supply 
Running  losseslnon  return 
Fuel  injection    

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- 
Fuel Injection 
ECM relay, testing 
The engine  control  module (ECM) relay is energized  via the 
ECM  and supplies battery  positive 
(Bc) power to many of  the 
engine management components and subsystems.  If this  re- 
lay  is faulty, the engine will not start. 
NOTE- 
The ECM relay  is also referred  to as  the DME main relay 
ECM  relay powers: 
ECM 
Ignition coils 
* Fuel  injection 
Evaporative leak detection  pump 
Idle air actuator 
- Camshaft sensors  Evaporative emissions  valve 
Hot  film  mass air flow sensor 
Fuel  pump relay 
Oxygen sensor heaters 
4 Working  in right rear  of engine compartment: 
Release interior ventilation filter cover latch 
(A) and  re- 
move  cover. 
Release plastic locking  tab 
(B). 
Rotate duct inward (arrow) to unlock from  bulk head  and 
remove duct. 
Release spring  lock 
(C) to  remove lower filter  housing. 
Slide filter  housing  away from inner fender to  remove. 
- Remove electrical box (E-box) cover fasteners and  remove 
cover. 
With  ignition  off, remove ECM relay  (arrow) in electronics 
box  (E-box)  at rear  of engine compartment,  right side. 
NOTE- 
Relay locations  can vary  Confirm relay  identification by 
matching  wiring colors  and terminal  numbers.    

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130-28 
Fuel Injection 
ECM Relay 
4 Check  for voltage  at terminal  6 (30) at reiay socket 
If  battery voltage  is present continue testing. 
if battery voltage  is  not present, check fuse  109 (80-amp 
fusible link) under passenger seat carpet.  See 610 Electri- 
cal 
Component Locations. 
- Reinstall relay  and turn  ignition  on. Gain access to back  side 
of  reiay socket  and check  for ground  at terminal 
4. 
If ground is  present continue testing. 
If  ground is  not present,  signal 
from ECM is missing. Check 
wire between  ECM and relay. 
- With ignition  on and  reiay installed, check lor battery voltage 
at terminal 
2. 
If  battery voltage  is present,  relay has energized  and is 
functioning  correctly. 
If  battery voltage  is not  present and 
ail earlier tests are OK, 
relay  is faulty  and should be  replaced. 
NOTE- 
If no faults  are found during testing  but power  is not  reaching 
the  ECM  or other  components,  check the fuses 
in the fuse 
carrier 
X8680 in the E-box. 
Mass  air flow (MAF) sensor,  checking and 
replacing 
4 The  hot f~lm mass air flow  (MAF) sensor sends a varying volt- 
age (approx. 0.5 - 4.5 vdc) to  the ECM representing  the mea- 
sured 
Intake air.  The alr mass input signal is produced 
electron~caily uslng an electrically  heated metal fllm in the  air 
flow stream. 
The  ECM relay  provides the  operating voltage to the  MAF 
sensor. As air 
flows through the  sensor, the film is cooled.  To 
maintain  the film  at a constant temperature, additional current 
is necessary.  It is  this  additional current that is the basis  lor 
the  input signal. 
If there is  no output signal from  the MAF sensor, the ECM op- 
erates  the engine  using the  throttle position and engine rpm 
inputs. A faulty  MAF sensor illuminates  the MIL.    

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Fuel Injection 
A faulty MAF sensor can produce the following  problems: 
Difficult  to restart  when  engine  is hot 
Engine starts  then stalls 
* Engine starts and runs  only with accelerator pedal  de- 
pressed 
4 Disconnect electrical harness connector  from MAF  sensor 
(B). 
- Turn ignition on and  checlc for voltage and ground  at connec- 
tor. 
There should be ground at pin 
1 and battery  voltage at pin 
3. 
- If any faults  are found,  checlc for wiring breaks  between 
MAF  sensor and ECM  and between MAF  sensor and main 
DME  relay. 
NOTE- 
Visually  inspect the sensor for damage,  missing or blocked 
screens.  The screens affect  air flow calibration.  Also inspect 
the  sealina 
0-rinas where the  sensor inserts into the air filter - - housing  and intake  boot. Ensure  the pin  connections are 
clean  and tight. 
4 Connect a  BMW-compatible scan  tool or an OED II generic 
scan tool. 
Checlc air  mass  signal (load signal) with the  engine 
at  idle.  Raise idle speed and 
checlc that load  signal changes 
with rpm. 
CAUTION- 
Be  sure ignition  is OFFbefore disconnecting or  reconnecting 
DME  system  components. 
Remove  MAF sensor: 
Loosen  intake boot clamp 
(A). 
Disconnect harness connector (6). 
* Release clip  from air filter housing (C) and remove sensor. 
- Installation is  reverse of removal. 
No  adjustment  to MAF  sensor  is possible. 
Check intake  hoses for cracks  and vacuum 
lealts.    

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130-38 
Fuel Injection 
Throttle cable, adjusting 
(MS 42.0) 
The throttle assembly  on MS 42.0 cars uses a throttle cable. 
The  cable  should be  adjusted any  time it is  disconnected or 
replaced.  This procedure  requires the factory  scan tool or an 
equivalent  to read  and adjust throttle angle.  It is  recommend- 
ed  the procedure  be done  by an  authorized 
BMW dealer ser- 
vice  department 
Basic  adjustment: 
Ensure that at  idle (accelerator  pedal in rest position) throt- 
tle  cable  has detectable play  at throttle  lever attaching 
point.  Play must not exceed  maximum allowable. 
Adjust  by  turning knurled  adjuster 
(arrow) on end  of throt- 
tle  cable  sheath  at throttle  housing. 
NOTE- 
Faulty  throttle  adjustment  values must be reset  using  the 
BMW  service tester 
DISplus, MoDiC, GTI or equivalent. 
Max. 
play at throttle  plate lever 
ldle speed control  valve, 
checking and replacing 
3 mm (0.125 in) 
The Idle speed control  valve regulates Idle speed by red~rect- 
ing air around  the throttle valve.  The ldle speed  control valve 
is  mounted 
d~rectly above  the throttle housing. Accessing  the 
valve  is best accomplished by 
flrst removing  the air fllter 
housing  and associated ducting. 
Thevalve is supplied  with batteryvoltage  from the ECM relay. 
The  idle speed control  valve incorporates a two-coil rotary ac- 
tuator.  The ground  sides of each  coil are pulsed  simulta- 
neously  by the  ECM.  The duty cycle  of each circuit  is varied  to 
achieve the  required idle speed. 
A faulty  idle speed  control valve sets a fault  code and the  MIL 
is  illuminated  when 
OED II fault criteria  are exceeded. 
Before checking the  idle speed control valve, confirm that the 
throttle position  sensor is working correctly. 
- With  engine  running, check that  idle  speed control  valve is 
buzzing. 
- Turn  on AIC system or shift transmission  into  drive. ldle 
should  remain steady or increase  slightly. 
- If idle speed  valve is not buzzing, or  if idle  decreases when 
AIC is turned  on, stop engine and disconnect harness  con- 
nector  from idle speed  valve.    

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. - 
Fuel Injection I 
Working inside E-box, disconnect ECM harness  connector 
(arrow)  by releasing  fastener and pivoting  connector  up and 
off  ECM. 
CA UTIOW 
Be  sure ignition  is OFF before disconnecting  or reconnecting 
DME system components. 
Remove  ECM from  retaining brackets and lift off  holder. 
Installation is  reverse of removal 
Before attempting  to start engine,  use 
BMW service  tester 
DISplus, MoDiC, GTl or equivalent: 
* Code  replacement  ECM with application  information (i.e 
engine code, transmission  type, etc.). 
Align  ECM to EWS  (electronic  immobilizer). 
Siemens MS 42.0  and MS  43.0 
ECM  pin assignments 
ECM  pin assignments are given  in Table  c. For engine  man- 
agement system schematics,  see 
ELE Electrical Wiring Di- 
agrams. 
/ CAUTIOW I 
Al~ays wait  at least one mfnule after turning  off the ignition 
before 
remov;ng [he connecror  irom rhe ECM. If the con- 
nector  is removed  before this time,  residual power 
in the 
system relay  may damage  the 
ECM. 
Always connect  or disconnect  the control  module con- 
nector  and meter probes  with the ignition  off. 
When making checks  at the ECM  itself, a 
breakout box 
should  be used  to allow  tests to be  made  with the connector 
attached  to the  ECM.  This also prevents damage  to the small 
terminals  in the  connector. As  an alternative, the  harness 
connector housing  can be separated so  that electrical checks 
can be made  from the back  of the  connector. 
Table 
c. Siemens  MS 42.0 and MS 43.0 ECM  pin assignments 
Pin 
lslgnal l~om~onentlfunction 1 Notes 
Connector 
X60001 9-pin black 
1 loutput I~erminai 15 I Unloeder  relay terminal 15 
2 I 1 Not used I 
3 Not used 
4 Ground 
Ground  Ground 
point