1999 BMW 540i relay

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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