1999 BMW 528i THROTTLE BODY WIRING

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110-8
1 Engine Removal and Installation
4 M52 TU, M54 engine: Remove fasteners (arrows) retaining
wiring harness conduit to throttle body.
4 M52 TU, M54 engine: Working at throttle housing, rotate har-
ness plug (arrow) counterclockwise and remove.
4 M52 TU, M54 engine: Disconnect electrical harness connec-
tor at idle speed control valve (arrow), directly above throttle
valve.

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11 3-25
Cylinder Head Removal and Installation
4 Working beneath car (on left side under driver seat), remove
fuel filter cover and clamp
off fuel hose(s).
NOTE-
M54 engines use a single fuel line to the non-return fuel rail.
Disconnect fuel lines by pressing in on spring lock (arrows).
CAUTION--
Fuel may be expelled underpressure. Do not smoke or worlc
near heaters or other fire hazards. Keep a fire extinguisher
handy Before disconnecting fuel hoses, wrap a cloth around
fuel hoses to absorb any leaking fuel. Plug all open fuel lines.
NOJE-
BMW uses various styles of line connections; a one-time
band clamp; a
self-locl(ing connector (that use BMWspecial
tool 16 1 050 to release); and a quick release connector
(above).
4 M52 TU engine: Pull throttle cable out of rubber retainer (A)
and unhook ball end of cable (6) from throttle actuator.
4 Remove fasteners retaining wiring harness at throttle body
and support bracket (arrows).

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-. .
Cylinder Head and Valvetrain -- v . -- --- --
4 Remove air filter housing and ducts:
Loosen hose clamps as necessary and disconnect electri-
cal harnesses.
- Remove air filter housing mounting fastener (arrow).
Loosen hose clamp at throttle body.
Remove air filter housing with mass air flow sensor and
duct.
Disconnect the following electrical harness connectors.
Knoclc sensors (A).
Thermostat housing (B).
Throttle position sensor/throttle position switch and idle
valve
(C).
Camshaft position sensor (D).
* Ignition coils (E).
Remove mounting nuts (arrows)
ducting. from
wiring harness

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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