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.- 
/Fuel Injection 
I ' I - I 
9 /ln~ut l~oltaqe supply I Fuse carrier, engine electronics 
Table 
c. Siemens  MS 42.0  and MS 43.0  ECM  pin assignments (continued) I ' I . I 
Connector X60002 24-pin 
1 linput IHeater, precatalyst oxygen sensor 1 I Heated oxygen sensor 1 in front  of cat. conv. 
I I I 
18 llnout IHeater, post-catalyst oxygen sensor 2 ]Heated oxygen sensor 2 behind  cat. conv. 
Notes 
Ground connector 
Ground connector 
B+ terminal 
Fuse carrier, engine electronics 
Pin 
5 
6 
7 
8 
I I I 
4 loutput l~hrottle valve supply  (MS 
42.0) I~hrottle valve (MS 42) 
Signal 
Ground 
Ground  Input 
lnout 
19 
20  21 
22 
23 
24 
Connector 
1 
2 
3 
I I I 
5 1 lnput ISignal, intake camshaft position sensor /camshaft position sensor 1 
Componentlfunction 
Ground 
Ground 
Terminal  30 
Voltaae 
SUDP~V 
input 
Ground 
Ground 
Ground 
Input 
Ground 
X60003 52-pin 
Input 
Input 
~ - 
Heater, post-catalyst oxygen sensor 2 
Ground, precatalyst oxygen sensor 
1 
Ground, precatalyst oxygen sensor 2 
Ground, post catalyst oxygen sensor 
1 
ECM  (DME  main) relay signal activation 
Ground, post catalyst oxygen sensor 2 
Signal, mass air 
flow sensor 
Signal,  exhaust camshaft sensor 
Not  used  Heated 
oxygen sensor 2 behind  cat. 
conv. 
Heated oxygen sensor 1 in front  of cat.  conv. 
Heated oxygen sensor 2  in front  of cat.  conv. 
Heated  oxygen sensor 
1 behind cat.  conv. 
ECM 
Heated oxygen sensor 2 behind cat.  conv. 
Hot film  mass air flow sensor 
Camshaft position sensor    

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Fuel Injection 
Table c. Siemens  MS 42.0  and MS 43.0 ECM pin assignments (continued) 
Pin 
42 
43 
44 
45 
46 
47 
48 
49  50 
51 
52  Componentlfunction 
Signal, evaporative emissions valve 
Signal, throttle 
valve drive 
Signal, throttle  valve drive 
Signal, engine coolant thermostat 
Signal,  close idle  speed control valve 
Signal,  open idle  speed control  valve 
Signal, shield 
ltnock sensor 
Signal, resonance  valve 
intake system 
Not  used 
Not used 
Signal, secondary  air injection pump  valve 
Signal 
Input 
Input 
Input 
Input 
input 
Input 
Ground 
Input 
Input 
Notes 
Evaporative emissions  valve 
Throttle valve 
Throttle valve  Engine coolant thermostat (map controlled) 
idle  speed control  valve 
Idle speed control valve 
Shield, 
knock sensor 
Resonance  valve intake system 
Secondary  air injection  valve 
Connector 
X60004 40-pin  Notes 
instrument cluster control unit 
Instrument cluster control module 
Secondary air injection pump relay 
Electric (auxiliary) fan motor 
Pedal position sensor (PWG) (MS  43.0) 
Pedal position sensor (PWG) (MS  43.0) 
Pedal position sensor (PWG) (MS  43.0) 
Fuel pump relay 
1 
Instrument cluster control module 
ComponenVfunction 
Signal,  battery  charge indicator lamp 
Feedback signal, engine start 
Signal, secondary  air injection  pump 
Signal, electric cooling  fan 
Not  used 
Not  used 
Pedal position sensor (PWG)  (MS 43.0) 
Signal,  pedal position sensor  (PWG) (MS 43.0) 
Pedal position sensor (PWG)  (MS 43.0) 
Signal, 
fuel pump  relay 1 
Signal,  oil pressure switch 
Pin 
1 
2  3 
4 
5 
6 
7 
8 
9 
10 
11  Signal 
Input 
Input 
input 
input 
Input 
Input    

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130-46 
Fuel Injection 
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 
OED 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. 
CA UTIOiU- 
The tests  in this section  may set fault codes (DTCs) in the 
ECM  and illuminate the MIL.  After ail testing is  completed, 
access  and clear  DTC  fault 
memory using an OED I/ or 
BMW  compatible  scan tool. See OBD  On-Board  Diag- 
nostics. 
Only  use a digital 
multimeter for electrical  tests. 
Relay  positions  can vary.  Be sure to confirm  relay 
posi- 
. tion by identifying  the wiring  in the  socket using  the wir- 
ing diagrams-found in ~~~~lectrical Wiring 
Diagrams. 
NOTE- 
OED 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 link connector 
(DLC)  is in the right  rear of the engine  compartment. 
The  16-pin  OBD 
I1 diagnostic connector  (arrow) is located 
inside the  car on 
the lower left dash panel.    

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Fuel Injection 
M5.2 system features 
The Bosch M5.2  system used on 1997 540i  models uses  an 
88-pin control  unit. The 
M5.2 system has the following func- 
tions  and capabilities: 
Fully sequential cylinder-individual  fuel injection. 
Integrated adaptive knock control. 
Oxygen  sensor fuel mixture control. 
0 Self-diagnosis  and emergency operation characteristics. 
CAN-Bus  link. 
0 OED II functions  (misfire detection,  catalytic converter 
monitoring,  oxygen sensor monitor, and fuel  tank ventila- 
tion  system). 
Electronic vehicle immobilization via  EWS. 
One-touch starter function. 
Control  of characteristic  map thermostat. 
M5.2.1 system features 
The  Bosch M5.2.1 system is used  on 1998 540i  models. The 
M5.2.1  control module utilizes  the SKE (standard shell con- 
struction  housing) with 5 connectors and a combined total  of 
134  pins. 
The  M5.2.1  systefn  has 
tile following functions or capabilities: 
Separate power supply relay for ignition coils.  Leak diagnosis pump (LDP)  control and feedback 
rnonitor- 
ing for evaporative system leak testing. 
Fuel  evaporative system providing  ORVR (on-board refuel- 
ing  vapor  recovery) compliancy. 
Batterylalternator charge  logic  (idle speed varied  with the 
battery  state of charge). 
CAN-Bus  communications with  the instrument cluster 
EWS 
Ill "rolling code"  ISN interface. 
More  sensitive  ignition 
knock sensors. 
Pulse  width modulated (P-W-M) Heating and 
AIC (IHKA) 
status signal. 
Running  loss (312-way)  solenoid valve.    

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- Fuel Injection 
ECM relay, testing 
The engine control module (ECM) relay is energized via  the 
ECM and  supplies battery positive 
(B+) power to many  of the 
engine 
management components and subsystems.  If this re- 
lay is faulty,  the engine will not start. 
CAUTIOI\C 
Relay positions can vary. Be sure  to confirm relay position  by 
identifying  the wiring 
in the socket  using the wiring  diagrams 
in ELE Electrical Wiring  Diagrams. 
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 
(5.2.1 only) 
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 unloclc from bulk head  and 
remove  duct. 
0 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.    

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130-50 
Fuel Injection 
Bosch M5.2 
ECM relay 
1 HoL al ail iirnel XOL a1 ail limes 
i--[-----i F109 (BOA) electronics I L.$.....: .I: 
ECM relay . . . . . . . . . , 
8,s 
:, 
6 1 .. ... ~~.~~. . ...... .-, Engine control ii~~-~.~~..~ ........ ~~~~~~.~~~~:. module relay -;I 
Of? 
,c,;,,, 
< With ignition  off, remove ECM relay  (arrow) in electronics 
box (E-box)  at right rear  of engine  compartment. 
NOTE- 
Relay locations can  vary. Conh relay identification  by 
matcliing  wiring colors  and terminal  numbers. 
4 Check for voltage  at terminal 6 of main  relay socket  (30-red 
wire).  On M5.2  cars also check  for battery  voltage  at terminal 
8. 
. . . . . . . . . , 
If  battery voltage  is present, continue  testing 
. 
If battery voltage  is not present, check  large red wire(s) in 
relay socltet. See 
ELE Electrical  Wiring Diagrams. 
%P,,tt 
- Reinstall  relay and turn  ignition on. Gain access to underside 
of  relay socket and 
checlc for  ground  at terminal 4 (85-brown 
wire). 
. . . . . . .  . . . . . - - - - - - - - - . - - - . . l ,,-. ; Engine i f .: , ; Fuse  carrier .,A . :engine /;is? /control L.!.!! .... 1.: ...... !.::..! I lij :module  electronics If 
ground is present, continue  testing 
If ground is not present, signal from  ECM is missing. Checic 
wire between  ECM and  relay. 
4 With ignition on and relay installed, check  for battery  voltage 
at terminal 
2 (87-redlwhite wire).  On M5.2.1  cars also checlc 
for battery  voltage  at terminal  5. 
If battery voltage is present, relay has energized and is 
functioning  correctly. 
If  battery  voltage  is not  present  and all earlier tests are  OK, 
relay is  faulty and should  be replaced.    

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Fuel Injection I 
4 Release spring  clips (arrows) from fuel injectors and  pull in- 
jector  electrical  loom straight  up to remove. 
4 Check that  ECM signal is present  at injector connectors. 
- Connect  digital voltmeter  to fuel injector harness plug. 
Operate  starter and 
check for voltage pulse. 
* Repeat for  each injector. 
- Remove fuel injectors by removing retaining clips 
- Installation is reverse  of removal: 
Fit new O-rings when installing injectors.  For ease  of instal- 
lation,  lightly lubricate  all fuel system O-rings with assem- 
bly lubricant. 
Check that  injector electrical connections are  correctly fit- 
ted and  that 
injectors are fully seated  prior to installing  iuel 
rail mounting bolts. 
Mass  air flow sensor  (MAF),  replacing 
The MAF sensor is provided  with operating power from  the 
ECM  relay.  Based on  calculated intake air mass,  the MAF 
generates 
avarying voltage (approx. 0.5 - 4.5 vdc)  as an  input 
signal to  the ECM. 
4 Remove  MAF sensor: 
Remove upper  air filter  housing locking clips. 
Unscrew and remove  MAF sensor harness 
(A). 
Disconnect intake air temperature sensor harness (B). 
Loosen  hose clamp (C). 
Remove upper filter  housing with sensor. 
- Installation is reverse  of removal    

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130-54 
I Fuel Injection ldle speed control  valve, 
testing  and replacing 
ldle speed  is maintained  by the ECM through  the idle speed 
control  valve. The idle control function compensates  for en- 
gine load  and engine  operating conditions.  ldle speed is 
adaptive through  the ECM and  no adjustments  can be made. 
Before checking  valve, confirm that throttle position sensor  is 
working  correctly. 
NOTE- 
The test given  below  is an  electrical check  only. It does  not 
check the  mechanical  operation of the  valve.  If the  valve  is 
sticking, hanging up or is sluggish in operation,  substituting  a 
Inown good valve is the  best  way to  check it. 
With  engine  running, check  that idle speed  control valve  is 
buzzing. 
Turn  on 
AIC or shift  car into drive.  ldle should  remain steady 
or increase  slightly. 
If  valve  is not  buzzing, or if  idle decreases  in step above,  stop 
engine  and disconnect  harness connector from  valve. 
4 Check resistance of valve across its terminals.  Test values 
are  listed  below. 
ldle  speed  control  valve coil resistance 
Terminals 
1 and 2 20 +2% 
Terminals 2 and 3 20 +2Q 
Terminals 1 and 3 40 +4% 
NOTE- 
If you  suspect  an intermittent  fault, lightly  tap the  valve  while 
testing  resistance. 
With valve harness connector disconnected, check  for bat- 
tery voltage  at redlwhite  wire in connector with  ignition on. 
If . ~~ ~~ 
there is  no voltage, check  wiring between connector and 7 ECM relay.  See ELE Electrical  Wiring Diagrams. 
NOTE- - The idle speed  control  valve receivespositive (+) battery  volt- 
age  from  the ECM  (DME  main) relay