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Battery check BMW 3-Series 1998 - 2006 Petrol 318i - 2.0

OnDemand step-by-step maintenance & repair BETA

BMW 3-Series 1998 - 2006  | 318i - 2.0 Battery check

  • time 10 minutes
  • difficulty 2
The battery is in the boot
Open the battery cover
Remove the bracket to access the battery
Undo the retaining bracket - use a 10mm spanner or socket
Check the Negative (-) terminal clamp is tight
Check the Positive (+) terminal clamp is tight. CAUTION If using a spanner to tighten terminal, be careful not to short the spanner on the bodywork
Check battery is generally secure, if loose, tighten the battery retainer
The battery retaining clamp position
To tighten, a 13mm socket is needed. Not too tight as you may damage the battery casing. If you have to replace the battery, click below
- Close + Open

Battery removal & replacement

Note: When the battery is disconnected, any fault codes stored in the engine management ECM memory will be erased. If any faults are suspected, do not disconnect the battery until the fault codes have been read by a BMW dealer or specialist. If the vehicle is fitted with a code-protected radio, refer to ‘Audio unit anti-theft system’.
Note: After reconnect the battery, it will be necessary to carry out the sunroof initialisation procedure as described at the end of this Section.

Removal

1 The battery is located beneath a cover on the right-hand side of the luggage compartment.
2 Open the boot lid, and lift the luggage compartment floor.
3 On Saloon and Coupe models, rotate the fasteners 90° anti-clockwise, and partially remove the left-hand side luggage compartment side trim, and unclip the battery cover/first aid kit tray from the right-hand side of the luggage compartment (see illustrations) . On Touring models, press the button to release the trim panel below the right-hand side rear window. Undo the two nuts and remove the battery cover/storage tray above the battery (see illustration) .
Rotate the fastener anti-clockwise
Remove the battery cover/tray
Undo the two nuts and remove the battery cover – Touring models
4 Slacken the clamp nut, and disconnect the clamp from the battery negative (earth) terminal (see illustrations) .
Slacken the negative terminal clamp bolt . . .
. . . and disconnect the terminal from the battery
5 Remove the insulation cover (where fitted) and disconnect the positive terminal lead in the same way.
6 Slacken the clamping plate bolt, then unscrew the bolts, and remove the battery retaining clamp (see illustration) .
Slacken the clamping plate bolt (arrowed)
7 Lift the battery from its housing, disconnect the vent hose as the battery is removed. Take care as the battery is heavy!

Refitting

8 Refitting is a reversal of removal, but smear petroleum jelly on the terminals after reconnecting the leads to combat corrosion, and always reconnect the positive lead first, and the negative lead last.

Sunroof Initialisation

9 With the battery reconnected, and the ignition on, press the sunroof operating switch into the ‘tilt’ position and hold it there.
10 Once the sunroof has reached the ‘fully-tilted’ position, hold the switch in that position for approximately 20 seconds. Initialisation is complete when the sunroof briefly lifts at the rear again.
Replace battery cover. If you have to replace the alternator, click below
- Close + Open

Alternator replacement

1 Disconnect the battery negative lead.
6 Remove the auxiliary drivebelt.

Refitting

11 Refitting is a reversal of removal, but ensure that the drivebelt guide pulley is correctly fitted as noted before removal, and refit the auxiliary drivebelt. Where applicable, make sure that the lug on the drivebelt guide pulley engages with the cut-out in the alternator.
16 Remove the alternator drivebelt.
24 Remove the auxiliary drivebelt.

Refitting

30 Refitting is a reversal of removal, bearing in mind the following points.
  1. When refitting the tensioner idler pulley, ensure that the lug on the rear of the pulley assembly engages with the corresponding cut-out in the mounting bracket.
  2. Refit the auxiliary drivebelt.

M43TU engines

2 Disconnect the wiring plug, squeeze together the sides of the retaining collar and disconnect the fuel tank vent hose from the vent valve on the side of the air cleaner housing (see illustration) .
Squeeze together the sides of the locking collar and disconnect the hose from the vent valve
3 Rotate the vent valve 90° anti-clockwise whilst pulling it up, and remove it from the bracket on the housing.
4 Where fitted, undo the nut and bolt, then remove the cruise control actuator from the left-hand inner wing.
5 Release the housing-to-airflow meter retaining clips, undo the retaining bolt, unclip the air inlet neck, and remove the air cleaner housing from the engine compartment (see illustrations) . Recover the sealing ring.
Undo the retaining bolt (arrowed) . . .
. . . and remove the air cleaner housing
7 Prise the cover(s) from the rear of the alternator, then unscrew the nut, and disconnect the wiring (see illustration) .
To disconnect the alternator wiring, pull back the rubber cover and unscrew the nut (arrowed) then unplug the connector (arrowed)
8 Where applicable, prise the cover from the centre of the drivebelt guide pulley, then unscrew the pulley for access to the upper alternator securing bolt. Note the location of the pulley to ensure correct refitting.
9 Counterhold the nuts and unscrew the upper and lower alternator securing through-bolts (see illustrations) .
Alternator upper mounting bolt (arrowed) . . .
. . . and lower mounting bolt (arrowed)
10 Withdraw the alternator from the engine.

N42 and N46 engines

12 Lever out the expansion rivets, lift the air inlet hood approximately 5 cm, and pull it from the air cleaner housing and windscreen washer reservoir. Remove it from the vehicle.
13 Undo the two nuts, and pull the front edge of the plastic cover on the top of the engine forward and remove it (see illustration) .
Undo the two nuts (arrowed) and pull the cover forward
14 Release the inlet hose clamp from the throttle body, disconnect the vacuum hose (N42 engines only), and undo the two bolts securing the housing to the inner wing (see illustration) .
Undo the air filter housing bolts
15 Lift the housing up and out, disconnecting the wiring plug and the hose from the throttle body as the housing is removed.
17 On N42 engines, at the front of the alternator, undo the bolt at the top of the cable retaining plate, and free the cables and hoses from the plate (see illustration) .
Undo the bolt above the alternator at the top of the cable retaining plate (arrowed)
18 Unlock and disconnect the wiring plug, then unscrew the nut and disconnect the battery lead from the rear of the alternator (see illustration) .
Undo the nut (arrowed) and disconnect the alternator wiring
19 Undo the two lower bolts, and manoeuvre the alternator from the engine compartment (see illustration) .
Undo the lower alternator mounting bolts (arrowed)

Refitting

20 Refitting is a reversal of removal, tightening the mounting bolts to 21 Nm (15 Ibf ft).

6-cylinder engines

21 Release the engine wiring harness from the retaining bracket on the air cleaner housing.
22 Release the two clips and disconnect the inlet hose from the top section of the housing.
23 Unscrew the two retaining bolts and remove the air cleaner housing from the engine compartment, disengaging it from the inlet ducting as it is withdrawn (see illustration) .
Air cleaner housing bolts – 6-cylinder models
25 Remove the power steering pump reservoir mounting bolts, and position the reservoir to one side. There is no need to disconnect the fluid hoses.
26 Reach beneath the alternator and pull the air cooling hose down and off of the alternator rear cover.
27 Pull off the cover (where fitted), then unscrew the nut and disconnect the wiring from the rear of the alternator (see illustration) .
Disconnect the wiring from the rear of the alternator
28 Undo the upper and lower alternator securing bolts (see illustration) .
Undo the upper and lower alternator mounting bolts (arrowed)
29 Withdraw the alternator from the engine.
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