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.-. .
Battery, Starter, Alternator
Warnings and cautions
WARNING -
Wear goggles, rubber gloves, and a rubber apron when
working around the battery or battery acid (electrolyte).
Battery acid contains sulfuric acid and can cause skin
irritation and burning.
If acid is spilled on your skin or
clothing, flush the area at once with large quantities of
water. If electrolyte gets into your eyes, flush them with
large quantities of clean water for several minutes and
call a physician.
Batteries that are being charged or are fully charged
give off explosive hydrogen gas. Keep sparks and open
flames away. Do not
smoke.
CA UTIOI\C
Only use a digital multimeter when testing automotive elec-
trical components.
. If a repair procedure specifies disconnecting the bat-
tery, follow the instruction for safety reasons.
Prior to disconnecting the battery, read the battery dis-
connection cautions in
001 General Cautions and
Warnings.
Models with MS43 engine management: Allow at least
3 minutes to elapse after turning ignition ley to OFFpo-
sition before disconnecting battery. This willallow sum-
cient tinie to complete the DMJL (fuel tank pressure)
test
* Disconnecting the battery cables may erase fault codes
stored in ECM memory.
Always disconnect the negative
(-) battery cable first
and reconnect it last. Cover the battery post with an in-
sulating material whenever the cable is removed.
Do not disconnect battery, alternator or starter wires
while the engine is running.
0 Never reverse the battery cables. Even a momentary
wrong connection can damage the alternator or other
electrical components.
Do not depend on the color of insulation to tell battery
positive and negative cables apart. Label cables before
removing.
The slide-tilt sunroof may fail to function properly
after
disconnecting and reconnecting the battery. Reinitial-
ize sunroof as described in 540 Sunroof.
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Fuel Injection
Warnings and cautions
For personal safety, as well as the protection of sensitive
electronic components, adhere to the warnings and cautions
on the following pages.
WARNING-
Gasoline is highly flammable and its vapors are explosive.
Do not smoke or work on a car near heaters or other fire
hazards when diagnosing and repairing fuel system prob-
lems. Have a fire extinguisher available in case of an emer-
gency
Renew fuel system hoses, clamps and O-rings any
time they are removed.
When working on an open fuel system, wear suitable
hand protection, as prolonged contact
with fuel can
cause illnesses and skin disorders.
* The ignition system produces high voltages that can be
fatal. Avoid contact with exposed terminals. Use ex-
treme caution when
working on a car with the ignition
switched on or the engine running.
CAUTION-
- Disconnecting the battery may erase fault code($ storedin
memory Check for fault codes prior to disconnecting the
battery cables. Read the battery disconnection cautions in
001 General Warnings and Cautions.
a Connect and disconnect the DME system wiring and
1 test equipment leads only when the ignition is switched
off.
Wait at least 1 minute after turning off the ignition be-
fore removing the engine control module (ECM) con-
nector. If the connector is removed before this time,
residualpower in the system relay may damage the
control module.
Fuel system cleaners and other chemical additives oth-
er than those specifically recommended by BMW may
damage the catalytic converter, the oxygen sensor or
other fuel supply components.
* Do not connect any test equipment that delivers a 12-
volt power supply to terminal 15 (+) of the ignition coil.
The current flow may damage the ECM. In general,
connect test equipment only as specified by BMW or
the equipment maker.
Only use a digital
multirneter for electrical tests. Only
use an LED test light for
quiclc tests.
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130-6
Fuel Injection
Fuel supply to the injection system is provided by a high pres-
sure electric pump mounted inside the fuel tank. The pump is
powered via the fuel pump relay. If the relay is faulty, the fuel
pump will not run and the engine will not start.
NOTE-
* Fuel delivery volume and fuel pressure are critical to prop-
er operation. Fuel pressure direcfly influences fuel deliv-
ery
Fuel pump relay, fuel pressure and fuel volume tests are
given in 160 Fuel Tank and Fuel Pump.
Relieving system fuel pressure
The fuel system retains fuel pressure in the system when the
engine is off. To prevent fuel from spraying on a hot engine,
system fuel pressure should be relieved beforedisconnecting
fuel lines. One method is to tightly wrap
ashop towel around a
fuel line fitting and loosen or disconnect the fitting. Cleanli-
ness is essential when working with fuel components. Thor-
oughly clean the unions before disconnecting fuel lines.
When system faults are detected, a diagnostic trouble code
(DTC) is stored in the engine control module (ECM). The MIL
also iiluminates 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 the
ECM and illuminate the
MIL. Affer all testing is completed,
access and clear DJC fault memory using an
OED I1 or
BMW compatible scan tool. See OBD On-Board Diag-
nostics.
0 Only use a digital multimeter for electrical tests.
. Relay positions can vary Be sure to confirm relay posi-
tion by identifying the wiring in the socket using the wir-
ing diagrams found in ELE Electrical Wiring
Diagrams.
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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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130-46
Fuel Injection
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
OED 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.
CA UTIOiU-
The tests in this section may set fault codes (DTCs) in the
ECM and illuminate the MIL. After ail testing is completed,
access and clear DTC fault
memory using an OED I/ or
BMW compatible scan tool. See OBD On-Board Diag-
nostics.
Only use a digital
multimeter for electrical tests.
Relay positions can vary. Be sure to confirm relay
posi-
. tion by identifying the wiring in the socket using the wir-
ing diagrams-found in ~~~~lectrical Wiring
Diagrams.
NOTE-
OED 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 link connector
(DLC) is in the right rear of the engine compartment.
The 16-pin OBD
I1 diagnostic connector (arrow) is located
inside the car on
the lower left dash panel.
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Fuel Injection
Intake air temperature
([AT) sensor,
testing and replacing
Disconnect harness connector from intake air temperature
sensor
(A) at air filter housing.
Turn ignition on. Using a digital voltmeter, check for
5 volts
between supply voltage wire in connector and ground.
If volt-
age is not present, test ECM
inputs/outputs as described lat-
er.
With harness connector disconnected, test resistance across
sensor terminals. If any faults are found, replace IAT sensor.
IAT test resistance
0 lV *lac (50" i-2°F) 7-1 1.6 k.0.
020' kl°C (68' 322°F) 2.1-2.9 it.0.
080" ?lac (176" i-2°F) 0.27-0.40 itn
Auxiliary throttle valve (ADS)
(M62 and M62 TU engine), replacing
ADS components 540i models with ASC and DSC are fitted with a motor-driv-
en auxiliary throttle valve and housing ahead of the standard Throttle position switch throttle housing. The ADS throttle valve controls engine throt-
tle intervention based on signals from the DME control mod-
ule if road conditions, such as slipping driven wheel, warrant
reduced engine power.
ADS throttle housing
Bowden cable NOTE-
Before replacing the ADS throttle housing, read DME fault
ADS lhroltle actualor codes.
- ADS throttle housing replacement:
Switch off ignition and disconnect electrical connector on
ADS throttle body.
Remove hose from idle control valve.
Loosen hose clamps and remove throttle housing air in-
take boot.
Disconnect cable from ADS throttle body.
- Unscrew 3 bolts and remove ADS throttle body.
Installation is reverse of removal.
- Adjust cable so that no free play is present.
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Fuel Injection
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, GTl 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.
CA UTIOI\C
The tests in this section may set fault codes (DTCs) in the
ECM and illuminate the MIL. After all testing is completed,
access and clear DTC fault memory using an OBD
I1 or
BMW compatible scan tool. See OBD On-Board Diag-
nostics.
. Only use a digital multimeter for electrical tests.
Relay positions can vary. Be sure to confirm relay posi-
tion by identifying the wiring in the
socket using the wir-
ing diagrams found in ELE Electrical Wiring
Diaqrams.
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.
0 The BMW-dedicated 20-pin diagnostic link connector
(DLC) is in the right rear of the engine compartment. The
20-pin DLC was eliminated on models after
6/2000.
The 16-pin OBD I1 diagnostic connector (arrow) is located
inside the car on the lower left dash panel.
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Fuel Tank and Fuel Pump
Evaporative system troubleshooting
- Start by accessing diagnostic trouble codes (DTCs) using a
BMW or BMW compatible aftermarket scan tool.
For purposes of OBD
II emissions compliance, the DME
system sets a diagnostic trouble code (DTC) when it de-
tects a leak that is equal or larger than minimum
lealc
sensed by system.
Malfunction Indicator Light (MIL) is illuminated upon sec-
ond recurrence of fault. See OBD On-Board Diagnostics.
- When leak testing, observe following conditions to obtain
plausible results:
Fuel tank
'1, to 'I., full.
0 Vehicle parked for at least 2 hours to allow fuel to reach
room temperature.
Ideal fuel temperature is 10"- 20°C
(50"
- 68" F).
Do not refuel immediately before
lealc test.
- If a leak is detected, check the following areas:
* Fuel filter cap (leaking or off).
Fuel tank ventilation lines leaking at fuel
tank or activated
carbon canister.
i
Tank ventilation valve leaking (in engine compartment).
Fuel level
sensorlfuel pump cap leaking.
Evaporative system component replacement is covered later
in
th~s group in Fuel Tank and Fuel Lines.