battery BMW 525i 1998 E39 Workshop Manual

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160-8
I Fuel Tank and Fuel Pump
4 Disconnect harness connector from tank sending unit by
sliding connection lock to release connector.
Connect voltmeter between fuel pump terminals on
connector.
NOTE-
Fuel pump power (+) is supplied through the white/blue wire
Ground
(-) is supplied by the brown wire.
With jumper wire connected in place of fuel pump relay as
described above, check for battery voltage at fuel pump
harness connector terminals.
If voltage and ground are present, fuel pump is probably
faulty. If there is no voltage, check wiring between fuel pump
and relay.

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.- -
Fuel Tank and Fuel purnpl
Fuel pump power consumption, testing
To achieve accurate test results, the battery voltage at the
fuel pump connector should be
12.6 volts. Charge the battery
as necessary.
A higher than normal power consumption may indicate a
worn fuel pump, which may cause intermittent fuel starvation
due to pump overheating and seizure. The only remedy is
pump replacement.
A lower than normal power consumption
may indicate a blockage. Be sure to check that the return line
and the pump pickup are not obstructed before replacing the
pump.
- Expose right side access cover:
Peel forward lip of carpet.
Release rubber grommet from center of access cover insu-
lation.
Peel back insulation at perforations to expose fuel tank ac-
cess cover.
Remove right side cover to expose electrical harness con-
nector.
Disconnect harness connector from tank sending unit by slid-
ing lock back. Lift off connector.
Test fuel pump for current draw by attaching digital ammeter
between pump and harness (terminal
2, whitelblue wire) and
connect a jumper wire between pump and harness (terminal
1, brown wire) as shown.
CAUTION-
Do not allow the test leads to short to ground.
NOTE-
See 600 Electrical Systern-General for information on elec-
trical tests
using a digital multirneter.
Run pump as described in Operating fuel pump for tests.
- Compare ammeter reading with specification listed in ac-
companying table.
Fuel
pump current
Current consumption (average) 9.5 amps

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err- .- Fuel Tank and Fuel Pump
FUELPUMP AND FUELLEVELSENDER
E39 models use a two-lobed fuel tank. Each lobe of the tank
has its own fuel level sending unit. Each sender has a float
connected to a variable resistance wipercontact. To equalize
fuel level between the two
tank lobes, a siphon pump is in-
stalled in the left lobe.
When replacing asender or fuel pump, always replace hose
clamps,
gasltets and O-rings.
WARNING
-
When removing the fuel level sender or the fuel pump, the
fuel tank should be drained to
1/4 capacity or below as de-
scribed later in this repair group.
NOTE-
The compensating siphon pump maintains the fuel level be-
tween the right and left tank lobes. If fuel level sender resis-
tances are not approximately the same on left and right,
remove the senders and visually inspect the level in each
lobe. If the levels are different, check the siphon pump.
Fuel level sender resistances
Float position
l~est results (Q
Down (empty) 150- 70
Up (full) 1401 -415
Fuel level sender (right side) and fuel
pump, removing
and installing
- Drain fuel from tank as described later.
- Disconnect negative cable from battery.
CAUTION-
Prior to disconnecting the battery, read the battery discon-
nection cautions given in
001 General Cautions and
Warnings.
- To access top of fuel tank, remove rear seat lower cushion by
lifting front edge
off catches.

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--
I Fuel Tank and Fuel Pump
The plastic fuel tank is mounted underneath the center of the
car (underneath the rear seat). Mounted in the fuel tank are
the fuel pump and fuel level sending units. Connecting lines
for the evaporative emission control system and expansion
tank are also attached to the tank.
Fuel
tank capacity for E39 models
Tank capacity
70 liters (18.5 gal)
Reserve capacity
8 liters (2.1 gal)
Fuel tank, draining
Drain fuel tank into a safe storage unit using an approved fuel
pumping device.
WARNING-
# Before removing tank, be sure that all hot components,
such as the exhaust system, are completely cooled down.
Fuel may be spilled. Do not smoke or
work near heat-
ers or other fire hazards.
- Start engine and allow to run 10 - 15 seconds to fill fuel com-
pensating siphon assembly. This will allow both lobes of fuel
tank to he drawn off through fuel filler pipe,
- Disconnect negative cable from battery.
CAUTION-
Prior to disconnecting the batteg read the battery discon-
nection cautions given
in 001 General Warnings and Cau-
tions.
- Remove fuel tank filler cap
- Slide suction hose into filler neck about 130 cm (51 in.), twist-
ing as necessary. Withdraw fuel into storage unit.
- Monitor fuel level reduction in both lobes:
- Remove rear seat cushion and access both fuel tank send-
er harness connectors.
Use multimeter to measure resistance at both senders,
Resistance should drop as fuel level drops.
- If siphoning mechanism is faulty, drain left tank lobe sepa-
rately by removing sender cover and pumping fuel directly
out of left lobe.

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Fuel Tank and Fuel pump/
- Remove suction hose from tank filler neck carefully to avoid
damaging filler neck baffle plate.
CAUTION-
After finishing repairs but before starling engine, be sure
there is at least
5 liters (1.5 gallons) of fuel in tanlc. The fuel
pump will be damaged if run without fuel.
Fuel tank, removing and installing
- Remove fuel tank filler cap and drain tank as described
earlier.
- Disconnect negative cable from battery.
CAUTION-
Prior to disconnecting the battea read the battery discon-
nection cautions given in
001 General Cautions and
Warnings.
- Remove rear seat bottom cushion. Peel forward lip of carpet
from beneath seat cushion and carefully peel back insulation
to expose fuel tank access cover on left and right sides. Re-
move covers.
Disconnect right side supply hose and
electr~cal harness
connector (arrows).
D~sconnect left side return hose and electrical harness
connector.
Working inside car, disconnect parking
bralte cable ends
from parking brake lever. See
340 Brakes.
Lift car and support safely.
Make sure the car is stable and
we/ supported at all times.
Use a professional automotive lift
orjack stands designed for
the purpose. A floorjaclc is not adequate support.
- Remove complete exhaust system and heat shield. See 180
Exhaust System.
- Remove drive shaft. See 260 Driveshaft

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170-5
Radiator and Cooling System
Fan switch calibration (M52, M62 engine)
coniprairoi OUt rlgnal
Auto. ciimilte ~ontioi inpuls via CAN bus
Electric fan activation:
Low speed
91°C (196°F)
High speed 104' C (21 9' F)
< In models manufactured after 911998 (M52 TU engine, M54
engine.
M62 TU engine), the electric cooling fan is controlled
by the engine control module (ECM) via the output final
stage.
The output final stage is mounted on the fan housing, next to
the fan motor. The fan is operated using a pulse width modu-
lated signal. Fan circuit wiring is protected by a 50-amp fuse.
Electric fan activation is based on the following inputs to the
ECM:
Radiator outlet temperature
Calculated catalytic converter temperature
Vehicle speed
* Battery voltage
Calculated
A/C pressure
When the vehicle is first started, the ECM activates the elec-
tric fan briefly at 20% of its maximum speed, then switches
off. This is for diagnostic monitoring. The voltage generated
by the fan when it slows down (acting as a generator) must
match the stored rpm values in the fan output stage toconfirm
that the fan is operating correctly.
NOTE-
If the ECM fault memory indicates a cooling fan fault, check
that the fan is not seized and that it spins freely.
When
A/C is switched ON, the electric fan is not immedi-
ately turned on.
After the engine is switched
OFF the fan may continue to
run at varying speeds for up to 10 minutes, based on cal-
culated catalyst temperature.
Transmission fluid heat exchanger
Automatic transmission fluid lines circulate transmission fluid
(ATF) to and from a heat exchanger at the radiator.
All 6-cylinder
models andV-8 models produced to 911998 are
equipped with a transmission cooler located in a cooling cas-
sette in front of the radiator.

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Warnings and cautions
Obse~e the following warnings and cautions when worlting
on the cooling system.
WARNING -
. At normal operating temperature the cooling system is
pressurized. Allow the system to cool as long as possible
before opening (a minimum of one hour), then release the
cap slowly to allow safe release ofpressure.
a Releasing the coolant system pressure lowers the cool-
ant boilingpoint and the coolant may boil suddenly. Use
1 heavy and wear eye and face protection to
guard against scalding.
Use extreme care when draining and disposing of en-
gine coolant. Coolant is poisonous and lethal to hu-
mans andpets. Pets are attracted to coolant because
of its sweet smell and taste. Seek medical attention im-
mediately if coolant is ingested.
CAUTIOG
Avoid adding cold water to the coolant while the engine is
hot or overheated. If it is necessary to add coolant to a
hol
system, do so only with the engine running and coolanl
pump turning.
To avoid excess silicate gel precipitation in the cooling
system and loss of cooling capacity, use BMW coolant
or equivalent low silicate antifreeze.
a If oil enters the cooling system, the radiator, expansion
tank and heating circuit must be flushed with cleaning
agent. BMW recommends removal of the radiator and
expansion
tank to flush.
When
worlcing on the cooling system, cover the alter-
nator to protect it against coolant drips.
Prior to disconnecting the battery, read the battery dis-
connection cautions given in
001 General Warnings
and Cautions.
Begin the diagnosis of cooling system problems with a thor-
ough visual inspection.
If no visual faults are found, it is rec-
ommend that the engine control module (ECM) fault memory
be checked for stored diagnostic trouble codes
(DTCs) using
BMW scan tool
DlSplus or equivalent.

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Manual Transmission
- Thoroughly clean guide sleeve mounting bolts, sealing sur-
faces, and threads. Apply
Loctite8243 or equivalent thread
locking compound to guide sleeve bolts. Reinstall guide
sleeve and
spacer(s).
Tightening torques
Guide sleeve to transmission case
M6 10 Nm (89 in-lb)
* M8 x 22 18 Nm (13 ft-lb)
- Max30 25 Nm (18 ft-lb)
- Reinstall transmission.
TRANSMISSION REMOVAL AND
~NSTALLATION
Removal and installation of the transmission is best accorn-
plished on a lifl using a transmission jack.The engine must be
supported using appropriate support equipment. This allows
the engine to pivot on its mounts to access the upper
Torx-
head bolts at the bellhousing.
WARNING-
Male sure the car is stable and well supported at all times.
Use a professional aulomorive lift or jack slanos des~gned
lor the purpose. A floor jack is nor adequare supporr.
The removal of the transmission may upset the balance
of the vehicle on a
lifl.
Transmission, removing and installing
- Disconnect negative (-) cable from battery.
CAUTION-
Prior to disconnecting the battery, read the battery discon-
nection cautions given
in 001 Warnings and Cautions.
V-8 engine: Remove plastic engine cover.
Early models: pry out protective caps (arrows), then re-
move nuts securing cover. Lift off cover.
Later models: depress four studs to release, then
lift off
cover.
- Raise and safely support vehicle
- Remove engine splash shield from underside of vehicle
- Remove exhaust system and heat shields. See 180 Exhaust
System.

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240-1 0
Automatic Transmission
TRANSMISSION REMOVAL AND
INSTALLATION
Removal and installation of the transmission is best accorn-
plished on an automotive lift using a transmission jack. Use
caution and safe workshop practices when working beneath
car and lowering transmission.
Torx-head bolts are used to mount the transmission to the
bellhousing.
Besure to have appropriate tools on hand before
starting the job.
WARNING-
Be sure the vehicle is properly supported. The removal of the
transmission may upset the balance of the vehicle on a lift
CAUJION-
Tilting the engine to remove the transmission can lead to
damaae to various components due to
laclc of clearance. 1
Transmission, removing and installing
WARNING -
Allow engine and transmission to cool down before starting
work on the transmission.
- Disconnect negative (-) cable from battery.
CAUTION-
Prior to disconnecting the battery, read the battery discon-
nection cautions given in
001 General Cautions and
Warninas.
4 V-8 engine: Remove plastic engine cover.
Early models: pry out protective caps
(arrows), then re-
move nuts securing cover.
Lift off cover.
Later models: depress four studs to release, then lift off
cover.

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[~us~ension, Steering and Brakes - General
This section of the manual covers front and rear suspension,
braking and steering systems, and contains wheel, tire and
wheel alignment information and specifications. Also covered
here are the integrated braking and suspension systems in-
cluding
antilock braking (ABS), traction control (ASCIDSC),
and electronic height control (EHC).
Vehicle ride height information is at the end of this repair
group. Alignment information is in
320 Steering and Wheel
Alignment.
Aluminum suspension components
In order to reduce vehicle weight, aluminum suspension com-
ponents are used in some models. A test with a magnet will
easily reveal the metal used. If working with aluminum com-
ponents, be sure to read and follow the cautions below.
CAUTION-
* Due to the chemical and corrosion characteristics of alumi-
num, do not bring into contact with battery acid.
Do not use wire brushes with brass or iron bristles.
Only use brushes with stainless steel bristles.
Do not expose to flying sparks from
grinding/cutting op-
erations.
Do not subject to steel welding splashes.
Do not expose to temperatures over
80°C (176"F),
even for short periods. Temperatures in painting facili-
ties are not a problem.
The E39 front suspension subframe is used as a rigid mount-
ing platform for the front suspension arms, stabilizer bar and
steering gear.
The suspension arms, known as the lower control arms and
the tension struts (thrust arms), are connected to the
sub-
frame through rubber bushings. The arms are connected to
the steering
knucltles in a double pivot configuration.
Each front strut assembly includes a tubular strut and a coil
spring. The upper strut mount includes a bearing. The lower
end of each strut housing is fitted to the steering knuckle. The
integral wheel bearing and hub are bolted to the steering
Iknucltle.
6-cylinder and V-8 models use different steering systems and
other front suspension components.