1999 BMW 525i fuse

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130-1 3
Fuel Injection I
< Unplug harness connector (arrow) from sensor.
CAUTION-
Be sure ignition is OFF before disconnecting or reconnecting
DME system components.
NOTE-
Do not confuse the throttle position sensor on the main Nirot-
tle body with the throttle position switch on the secondary
throttle body, where applicable.
- Remove two mounting screws holding sensor to throttle
housing.
- Installation is reverse of removal. Clear adaptation settings
from ECM using BMW-compatible scan tool.
NOTE-
Poor idle quality may be noticeable for a period if the adapta-
tion settings are not cleared after installing new TPS.
ldle speed control valve,
checking and replacing
The idle speed control valve regulates idle speed by redirect-
inq airaround the throttlevalve.The idlespeed control valve is
mounted on the underside of the intake manifold adjacent to
the dipstick tube bracket. Accessing the valve is best accom-
plished by first removing the air filter housing and the throttle
body assembly.
The valve issupplied with
batteryvoltagefrom the ECM relay.
The idle speed control valve incorporates a two-coil rotary ac-
tuator. The ground sides of each coil are pulsed
sirnulta-
neously by the ECM. The duty cycle of each circuit is varied to
achieve the required idle speed.
Afaulty ldle speed control valve sets afault 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.

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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
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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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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130-51
Fuel Injection
Oxygen sensors, checking
The oxygen sensor provides an input voltage signal [0.2 vdc
(lean) to 0.8 vdc (rich)] to the
ECM based on the oxygen con-
tent in the exhaust gas. To generate voltage, the sensor tem-
perature must exceed 575"
F (300" C). Therefore the sensor
is electrically heated.
NO JE -
The test given below is not a conclusive test of oxygen sen-
sor efficiency and does not test how the oxygen sensor re-
acts to changing conditions. Pin numbers and wire colors
can vary Always check the wiring diagrams to confirm wire
color and pin assignment.
0 The oxygen sensorconnectorplugs are locatednext to the
catalytic converters.
With connector attached to sensor, connect digital voltmeter
between
A and B wires in connector.
WARNING -
Exhaust manifolds andpipes can be hot enough to cause se-
rious burns. Wear suitable heavy gloves and other appropri-
ate protection.
NOJE-
Connector style may vary depending on system application.
Consult wiring diagram for system-specific wiring. See
ELE
Electrical Wiring Diagrams.
Start engine.
A fluctuating voltage signal should show on the
meter.
If voltage is incorrect, turn engine off and check pre-
heater circuit as described below.
NOJE-
To check sensor response to lean and rich mixtures, create
an air leak.
Oxygen sensor
voltage at idle
- Connect digital voltmeterbetween sensor heaterwires (white
wires,
C and D). Start engine and check for battery voltage.
If voltage is not present, check oxygen sensor heater fuses.
0.2 to 0.8 vdc fluctuating
NOJE-
The oxygen sensor heater is powered via fusedpositive (+)
battery voltage and a switchedground from the ECM. See
ELE Electrical Wiring Diagrams for specific circuit informa-
tion.
- The ground side of the oxygen sensor heater circuit is pulsed
on and off by the
DME control module.

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Fuel Injection
- If voltage is present as described above, check wiring be-
tween ECM and valve. If no wiring faults are found, check
ECM signal to valve.
- When replacing idle speed control valve, clean and inspect
all sealing areas.
. Inspect sealing ring in throttle body and replace if neces-
sary.
Throttle position sensor (TPS),
testing and replacing
The throttle position sensor (arrow) is mounted on the side
of the primary throttle housing and is directly connected to
the throttle valve shaft. The ECM sends a voltage signal to
the potentiometer-type sensor and monitors the voltage that
comes back. Resistance decreases (voltage increases) as
the throttle opens.
NOTE-
Do not confuse the TPS on the primary throttle housing with
the throttle switch on the
ASC secondary throttle housing.
4 Check throttle position sensor function by disconnecting har-
ness connector and checking across terminals. If any faults
are found, replace throttle position sensor.
Engine coolant temperature (ECT) sensor,
testing and replacing
Throttle position sensor (M62 engine)
The ECT sensor is located on the front of the engine in the
coolanVthermostat flange.The ECTsensor is a dual tempera-
ture sensor. One circuit provides coolant temperature infor-
mation to the ECM while the other circuit provides coolant
temperature information to the instrument cluster.
The ECM determines the correct ignition timing and
airlfuel
mixture required for the engine by monitoring an applied volt-
age
(5 vdc) to the sensor. The voltage drop across the sensor
Test
value
5 vdc (approx.)
4.0 kR(approx.)
Continuously variable
from
1.0 to 4.0 kR
without interruption
Test
conditions
Harness connector
disconnected, ignition on
Harness connector
disconnected,
ignition on
Throttle plate rotated from idle to
full throttle position Test Terminal
Term.
1 at
harness
connector and ground
Term.
1 and term. 3 at
sensor
Term.
1 and term. 2 at
sensor

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130-60
/Fuel lniection
Tabled. Bosch M5.2 ECM pin assignments
Note
Pin
21
20 I output / Crankshaft position sensor (speed and position) I Crankshaft positionlrpm sensor
23
I - I I 29 1 output I Idle speed control - opening winding I Idle speed control valve (cycled ground)
Type
22
1 output I Cvl. 6 ignition signal (primary signal) I Cyl. 6 ignition coil (RZV adapter)
output
25
26
27
28
Component/function
24 1 outout I Cvl. 7 iqnition siqnal (primary signal) I Cyl. 7 ignition coil (RZV adapter)
output
4 outbut I' I - I Cyl. 3
fuel injection valve I Cyl. 3 fuel injection valve (cycled ground)
Camshaft position
sensor (cylinder reference)
output input
output
oround
30
31
32
ground Hall effect camshaft position sensor
Cyl. 3 ignition signal (primary signal)
output
I
Cyl. 3 ignition coil (RZV adapter)
. - . .. . .
Cyl. 2 ignition signal (primary signal)
Terminal 30
Engine control module relay
Ground for electronics and sensor shield
output
output
outout
Remaining output stages ground
(not iclnition and fuel iniection valves) Cyl.
2 ignition coil (RZV adapter)
Fuse carrier, engine electronics
Engine control module relay
Ground splice ,
Cyl. 2 fuel injection valve
Oxygen sensor heater signal
Cyl. 5
fuel injection valve
Cvl. 8 fuel iniection valve
AIC comuressor relav sianal
Heated oxygen sensor I in front of catalytic converter,
Heated oxygen sensor
iI in front of catalytic converter
Cyl.
5 fuel injection valve (cycled ground)
Cvl. 8 fuel iniection valve (cycled ground)
. -
Not used Ground point
Cyl.
2 fuel injection valve (cycled ground)
Heatinq and AIC control module (ground - compressor OFF)
38 Not used
40 39
1 I Not used
I'
I . I
I' I -. I
46 1 ground I Heated oxygen sensor signal (voltage 0.1-1.0 V) I Oxygen sensors
41
1 inuut I Knock
sensor signal I Knock sensor
input
I
I I
Instrument cluster
I' I I 55 1 ground I Ignition ground I Ground point
Knock sensor signal
43
1 I Not used I
Fuel reserve signal
42
Throttle position sensor
47
48
49
50
51
52
53
54
Knoclc sensor
input
45
1 outout I Hot film mass air flow sensor signal (0-5 V) I Hot film mass air flow sensor
Throttle position sensor signal
(0.4-4.2 V) 44
input
output
output
output
output
output
inout
I - I
Not used
Not used
Cyl. 1 ignition signal (primary signal)
Cyl. 5 ignition signal (primary signal)
Cyl. 4 ignition signal (primary signal)
Cyl. 8 ignition signal (primary signal)
Throttle position sensor
(c 5 V voltage supply)
Terminal 87
f> 10 V)
ignition switch
56
Cyl. 1 ignition coil (RZV adapter)
Cyi. 5 ignition coil (RZV adapter)
Cyi.
4ignition coil (RZV adapter)
Cyl. 8 ignition coil (RZV adapter)
Throttle position sensor
Fuse
F1
input Terminal 15 (> 10 V)

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130-62
Fuel Injection
Bosch M5.2.1
ECM pin assignments
(M62 from 911 997 to 911 998)
Table e. Bosch 5.2.1 ECM pin assignments
i I I
5 1 I Not used
I
I I
Note
I I I
7 lln~ut l~erminal 30 voltage supply I Fuse
F4
Description
Pin
Ground point right-hand drive
Ground connector
X6460
I I I
Signal
Connector
X60001
Ground 4 1
2
3 Ground
Ground point right-hand drive
Ground connector
X6460 6
8
9 1
2
3
4
5
Not used
Not used
Not used
-
6
7
8
9
10 11
12
Ground
Input
Connector
X60002
Output Input Input Output
Input Output
Grniind
. -
13
14
15
Ground
- .- -
Output
Ground
Ground
Ground
Ground
16
17
18
19
20
21 22
23
.
Terminal 87
Not used
Oxygen sensor heater
slgnal
Not used
CAN-Bus low
CAN-BUS high
Ground
Output Input
ln~ut
Fuse F1
Heater oxygen sensor II behind cataiytic converter
Back up light switch
Transmission control module (AGS)
Transmission control module
(AGS)
Ground connector X6480
Not used
Oxygen sensor heater signal
Oxygen sensor heater ground
Oxygen sensor heater ground
Oxygen sensor heater ground
Oxygen sensor heater ground
Not used
Input
Input
Output
Output
Output Heater oxygen sensor
I behind catalytic converter
Heater oxygen sensor
II behind catalytic converter
Heater oxygen sensor
1 in front of catalytic converter
Heater oxygen sensor
II in front of catalytic converter
Heater oxygen sensor I behind catalytic converter
Oxygen sensor heater ground
Oxygen sensor heater ground
Oxvqen sensor heater ground Heater oxygen sensor
iI in front
of catalytic converter
Heater oxygen sensor
II behind catalytic converter
Heater oxygen sensor
1 in front of catalytic converter . -
Oxygen sensor heater ground
Oxygen sensor heater ground
Signal, running losses
Oxygen sensor iieater ground
Not used
Not used
Not used
Terminal
85 control
Heater oxygen sensor II in front of catalytic converter
Heater oxygen sensor
I behind catalytic converter
Fuel changeover
(312 way valve) circuit
Heater oxygen sensor 1 in front of catalytic converter
Engine control module relay