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Ignition System
Remove intake manifold as described in 113 Cylinder Head
Remaval and Installation.
Remove knock sensor mounting bolts (arrows) on side of
cylinder block. Remove sensors.
I CAUTION- I
Note the installedangle of the knock sensors on the bloclt be-
fore removalit. Reinstall the sensors in the same position. Be
sure to use
a torque wrench when tightening the sensor
mounting bolts.
Clean
lknoclc sensor contact surfaces on engine bloclc and
sensors before installing.
Tightening torque
Knock sensor to engine
bloclc 20 Nm (15 ft-lb)
- Use scan tool to read out and clear ECM fault memory.
- Installation is reverse of removal.

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Battery, Starter, Alternator
Water-cooled alternator
The water-cooled alternator, used on 1999 and later M62 TU
engines, is a sealed unit housed inside the engine block wa-
ter jacket. It is cooled via the engine cooling system. It is a
"brushless" sealed unit that cannot be serviced. Maintaining
consistent alternator temperatures increases the life span of
the alternator, and elimination of the alternator cooling fan re-
duces alternator noise
significantly.
The M62 TU water-cooled alternator incorporates load start
reduction. This function is intended to shorten the duration of
engine starting, particularly at low ambienttemperatures. The
current load is limited to
20 amps during starting in order to re-
duce alternator braking torque on the engine. Following the
current limiting phase, full power output is then progressively
reached.
Charging system diagnostics requires special test equip-
ment. If the test equipment is not available, charging system
fault diagnosis can be performed by an authorized
BMW
dealer or other qualified repair shop. See Table a. Battery,
alternator and starter troubleshooting for general electri-
cal component troubleshooting.
Before checking the alternator, make sure the battery is fully
charged and capable of holding a charge. Check that the bat-
tery terminals are clean and tight and the alternator drive belt
is properly tensioned and not severely worn.
NOTE-
Some model require up to 15 second to reacli full alternator
output.
CA UTIOG
If the charge indicator light in the instrument cluster remains
on, the charge warning circuit in the instrument cluster may
be faulty. Check that the ground lead is securely
affached to
the grounding stud on the cylinder head
(A). Replacing the
instrument cluster before repairing the ground lead will both
damage the instrument cluster and cause the failure to
reoccur.

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- -
/Battery, Starter, Alternator -- - -. - --I
< Check for battery voltage at alternator terminal 30 (B+) (ar-
row):
Pull back rubber insulating cover at terminal 30 at rear of
alternator.
Connect voltmeter between terminal 30 and ground and
check for battery voltage.
If voltage is not present, check
wiring for faults.
NOTE-
On V-8 engines, access to the rear of the alternator is limited.
Check for battery voltage between the jump start post on the
left cylinder head and ground.
r Disconnect harness connector from alternator. Turn ianition
on and check for battery voltage between terminal
lgand
ground. If voltage is not present, check wiring and fuses for
faults.
Reconnect connector to alternator.
Locate the blue wire coming from terminal
61E of the alter-
nator connector. Carefully connect the positive
(+) test lead
to the wire using a piercing test lead end.
Turn ignition key on and check for voltage. Voltage should be
less than 1.5 VDC and charge indicator lamp should light.
- Making sure all test equipment and tools are clear, start en-
gine. Voltage should increase to
8.0 VDC or higher. The
charge indicator light should go out.
If voltage does not increase and system is not charging,
the fault is in alternator.
- If voltage does not increase, but system is charging, inter- - roaate svstem for faults usina an appropriate BMW scan - .. . tool and'reset fault memory.
- If a load tester is not available, a quick alternator output test
can be done by running engine at about 2000 rpm and turn-
- -
ing on electrical loads (fans, lights, rear window defroster, -
- and wipers). With all accessories on, battery voltage should
be above 12.6
V.

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Fuel Injection
CAUTION-
Be sure ignition is OFF before disconnecting or reconnecting
DME system components.
Remove engine coolant temperature sensor:
Unclip crankcase vent hose
(C) from cylinder head cover.
Remove plastic cover
(6) from atop intake manifold run-
ners.
Working under front of intake manifold, disconnect ECT
harness.
Unscrew ECT sensor
(C) from cylinder head.
Installation is reverse of removal:
Use new copper sealing washers when installing sensor.
Replace any engine coolant lost.
Tightening torque
Temperature sensor to cylinder head
13 Nm (10 it-lb)
Intake air temperature ([AT) sensor,
testing and replacing
4 The intake air temperature (IAT) sensor (arrow) signal is
used by the ECM to monitor intake air temperature for fuel
and
igntion adaptation. The sensor is .ocared in rne 'ntane
man:lold behind the throttle housng.
The ECM monitors an applied voltage (5 vdc) to the sensor
The voltage drop across the sensor varies as the intake air
temperature (sensor resistance) changes.
NOJE-
The IATsensor is an NTC (negative temperature coefficient)
type sensor. In other words, as the temperature rises, resis-
tance through the sensor decreases.
If the IAT sensor input is implausible, a
fault code is set.The
MIL is illuminated when OED II fault criteria are exceeded.
The ECM then operates the engine using only the engine
coolant temperature (ECT) sensor input.
The intake air temperature sensor can be tested using a
mul-
timeter across its terminals:
/ IAT sensor resistance @ 20" C (68°F) / 2.2 - 2.7 lkCk
~ -- ~~ -
CAUTION--
Be sure ignition is
OFFbefore disconnecting or reconnecting
DME system components.

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Fuel Injection
Engine coolant temperature
(ECT) sensor,
testing and replacing
4 The ECT sensor is located below cylinder 6 intake port at the
rear of the engine (1).
The ECT sensor is a dual temperature sensor. One circuit
provides coolant temperature information 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
forthe engine temperature by monitoring an
appliedvoltage
(5vdc) to the sensor.Thevoltage drop across
the sensor varies as the coolant temperature (sensor resis-
tance) changes.
NOTE-
The ECT sensor is an NTC (negative temperature coeffi-
cient) type sensor. In other words, as the temperature rises,
resistance through the sensor decreases.
If the ETC sensor input is faulty or non-plausible, the MIL is il-
luminated when the MIL is illuminated when
OED II fault crite-
ria are exceeded. The ECM assumes a substitute value
(80" C 11 76'F) to maintain engine operation. The ignition tim-
ing is set to a
conservativelsafe basic setting.
- Remove intake manifold to access ECT sensor on the M52
TU and the M54 engines. See 113 Cylinder Head Removal
and Installation.
- Check ECT sensor resistance using a multimeter at sensor
terminals.
WARNING -
Due to rislc of personal injury, be sure the engine is cold be-
fore removing ECT sensor connector.
ECT sensor resistance @ 20°C (68°F)
CAUTIOI\C
Be sure ignition is OFFbefore disconnecting or reconnecting
DME svstem components.
2.2 - 2.7 k
4 Disconnect ECT sensor harness connector (arrow). Un-
screw ECT sensor from cylinder head.

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Fuel Injection
- Installation is reverse of removal:
Use new copper sealing washers when installing sensor.
Replace any lost coolant.
Tightening torque
Temperature sensor to cylinder head
13 Nm (10 ft-lb)
Intake air temperature (IAT) sensor,
testing and replacing
4 The intake airtemperature (IAT) sensor, located at the top of
I the intake manifold, adapts (fine tunes) the fuel mixture and i
T engine timing based on varying intake air temperatures.
i If the intaite air temperature signal is implausible, a fault code
! is set and the MIL is illuminated when OBD I1 fault criteria are
I exceeded. The ECM then operates the engine using the ECT
i sensor sional inout as a back uo.
type sensor. In other words,
a> the temperature rises, resis-
tance through the sensor decreases.
lid I The IATsensor can be tested using a multimeter:
/IAT sensor resistance at 20'C (68°F) 2.2 - 2.7 kd
Remove engine cover by prying off plastic trim caps (arrows)
and removing nuts below caps.

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I Fuel lniection
varies as the coolant temperature (sensor resistance) chang-
es.
NOTE-
The ECT sensor is an NTC (negative temperature coeff-
cient) type sensor. In other words, as the temperature rises,
resistance through the sensor decreases.
If the ETC sensor input is faulty or non-plausible, the MILis il-
luminated when OBD
II fault criteria are exceeded. The ECM
assumes a substitute value
(8OoC/176"F) to maintain engine
operation. The ignition timing is set to a
conservativelsafe ba-
sic setting.
4 Disconnect ECT sensor harness (A)
- Checlc ECT sensor resistance using a multimeter at sensor
terminals
3 and 4. Peel back protective boot (B) to ID termi-
nal numbers on connector housing.
/ ECT sensor resistance @l 2O" C (68°F) 2.2 - 2.7 kd
WARNING -
Due to risk of personal injug be sure the engine is cold be-
fore disconnecting ECT harness connector.
Sensor replacement: Disconnect ECT sensor harness (A).
- Unscrew ECT sensor from cylinder head and install new sen-
sor.
Use new copper sealing washers
when installing sensor.
Replace any lost coolant.
Tightening torque
ECT sensor to coolant flange 13 Nm (I0 it-lb)

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Fuel Injection I
Engine coolant temperature (ECT) sensor,
testing
The ECT sensor is located on the front of the engine in the
coolant~thermostat flange. The ECT sensor is a dual temper-
ature 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. Thevoltage drop across the sensor
varies as the coolant temperature (sensor resistance) chang-
es.
NOTE-
The ECT sensor is an NTC (negative temperature coeffi-
cient) type sensor. In other words, as the temperature rises,
resistance through the sensor decreases.
If the ETC sensor input is faulty or non-plausible, the MIL is il-
luminated when OBD
II fault criteria are exceeded. The ECM
assumes a substitute value
(80" C/ 176°F) to maintain engine
operation. The ignition timing is set to a
conse~ativelsafe ba-
sic setting.
Disconnect harness from
ECTsensor (A) at coolant flange at
front of engine.
- Check ECT sensor resistance using a multimeter at sensor
terminals
3 and 4. Peel back protective boot (B) to ID termi-
nal numbers on connector housing.
I ECT sensor resistance @ 20" C (68°F) I 2.2 - 2.7 lkCi
Engine coolant temperature (ECT) sensor,
replacing
I WARNING-
/ Due to risk ofpersonal injury, be sure the engine is cold be- I
I fore replacin~~~~sensor. -
-
I
- Disconnect ECT sensor harness.
- Unscrew ECT sensor from cylinder head and install new sen-
sor.
Use new copper sealing washers when installing sensor.
Replace any lost coolant.
Tightening torque
ECT sensor to coolant flange 13 Nm (10 it-lb)