Installation kit – electrical components for trailer coupling BMW 3 Models (E30) – with and without Check-Control

EBA – 01 29 9 750 863
BMW Installation Instructions

There may be slight differences between the trailer couplings, depending on the manufacturer. Please refer to the manufacturer’s own fitting instructions.

The following equipment and tools are required for installation work:

1/4” ratchet V*” extension
1/4” socket heads, 10 and 13 mm
1/4” ratchet Vi ” extension
1/4” socket heads, 17 and 22 mm
Torque wrench, range 40 … 90 Nm
Screwdriver No. 4
Phillips screwdriver No. 2
Twist drills, 5 and 10.5 mm dia.
Shell boring bit, 36 mm dia.
Zinc powder paint
Small brush
Marking tool
Centre punch
Hammer Drill
Body filler
Round file
Tape measure

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Installation kit - electrical components for trailer coupling BMW 3 Models (E30) - with and without Check-Control

Take out the luggage compartment floor mat and the tail panel trim if necessary.

Unscrew nut (1) and screw (2) at left and right.

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Installation kit - electrical components for trailer coupling BMW 3 Models (E30) - with and without Check-Control

Unscrew the nut at left and right.

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Installation kit - electrical components for trailer coupling BMW 3 Models (E30) - with and without Check-Control

Remove the screw at left and right. Detach the bumper. Detach the bumper mountings at left and right.

(These mountings can be discarded — the bumper will later be attached to the trailer coupling.)

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Installation kit - electrical components for trailer coupling BMW 3 Models (E30) - with and without Check-Control

Release the nuts, lower the rear exhaust silencer app. 10 cm an secure to the car body.

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Installation kit - electrical components for trailer coupling BMW 3 Models (E30) - with and without Check-Control

Break out the marked panel (1) at the left and right. Coat the edges with zinc powder paint.

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Installation kit - electrical components for trailer coupling BMW 3 Models (E30) - with and without Check-Control

Insert the reinforcement (1) in the frame side member at the left and right.

Note:

If necessary, tap 10 mm (M 10) holes.

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Installation kit - electrical components for trailer coupling BMW 3 Models (E30) - with and without Check-Control

Attach the reinforcements (1) hand-tight to the bodywork with:

4 hex bolts, M 10×20

4 washers, 10.5 x 30 x 3 mm

Important:

Remove underseal from the body areas at which the trailer coupling is to be attached. Coat the bright metal areas with zinc powder paint.

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Installation kit - electrical components for trailer coupling BMW 3 Models (E30) - with and without Check-Control

Drill holes (a).

Drill holes (b), first drilling pilot holes with 5 mm bit.

A = 52 mm

D = 10.5 mm dia.

Deburr the holes and coat with zinc powder paint.

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Installation kit - electrical components for trailer coupling BMW 3 Models (E30) - with and without Check-Control

Mark out and drill the hole for the wiring (drill a pilot hole and use a shell boring bit for the main hole).

A = 24 mm
B = 20 mm
C = 36 mm dia.

Deburr the hole and coat with zinc powder paint. Clean the luggage compartment of drilling swarf.

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Installation kit - electrical components for trailer coupling BMW 3 Models (E30) - with and without Check-Control

Attach the trailer coupling with:
4 hex nuts, M 10
4 washers, 10.5x30x3 mm
Tighten nuts and bolts to 43 … 48 Nm.
Fully tighten the rear exhaust silencer.

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Installation kit - electrical components for trailer coupling BMW 3 Models (E30) - with and without Check-Control

Insert reinforcement panel (2).
Tighten nuts to 43 … 48 Nm and fit caps (1).
4 nuts, M 10 2 reinforcement panels Note:

Seal the holes (a).

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Installation kit - electrical components for trailer coupling BMW 3 Models (E30) - with and without Check-Control

Detach negative lead at battery.

Lift out BMW badge.

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Installation kit - electrical components for trailer coupling BMW 3 Models (E30) - with and without Check-Control

Mark steering wheel position in relation to steering column spindle.

Unscrew nut (1) and remove together with washer (2).

Important:

The steering wheel can only be removed with the steering lock disengaged.

When installing:

Tightening torque for the nut 73 … 85 Nm.

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Installation kit - electrical components for trailer coupling BMW 3 Models (E30) - with and without Check-Control

Remove instrument panel.

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Installation kit - electrical components for trailer coupling BMW 3 Models (E30) - with and without Check-Control

Remove lower section of steering column surround.

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Installation kit - electrical components for trailer coupling BMW 3 Models (E30) - with and without Check-Control

Insert bulb into the holder of the additional cable. Install the holder in the additional turn indicator repeater light base on the instrument carrier. (The instrument carrier has been removed to illustrate this work more clearly.) Run the cable to the steering column.

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Installation kit - electrical components for trailer coupling BMW 3 Models (E30) - with and without Check-Control

Screw on the brown earth (ground) cable (1).

Disconnect the plug housing from the turn indicator relay and connect cable (2) to compartment 4 of the plug housing.

Fit new turn indicator relay and attach plug.

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Installation kit - electrical components for trailer coupling BMW 3 Models (E30) - with and without Check-Control

Run the additional cable through the hole and fit rubber sleeve (1).

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Installation kit - electrical components for trailer coupling BMW 3 Models (E30) - with and without Check-Control

Connect the central plug.
Power supply to: Cable colour Terminal number
Left turn indicator blue/red 1/L
Rear fog light grey/violet 2/54G
Earth (ground) brown 3/31
Right turn indicator blue/black 4/R
Right rear light and license plate light grey/white 5/58R
Brake light green/red 6/54
Left rear light grey/yellow 7/58L

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Installation kit - electrical components for trailer coupling BMW 3 Models (E30) - with and without Check-Control

Pull rubber seal (1) on to socket.

Screw socket to holder.

Tap threads if necessary.

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Installation kit - electrical components for trailer coupling BMW 3 Models (E30) - with and without Check-Control

Remove luggage compartment lock.

Attach clips (1) and run the additional cable along the standard wiring harness to the rear lights.

Replace luggage compartment lock.

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Installation kit - electrical components for trailer coupling BMW 3 Models (E30) - with and without Check-Control

Remove bulb holders at left and right.

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Installation kit - electrical components for trailer coupling BMW 3 Models (E30) - with and without Check-Control

Press the socket (1) out of the holder and connect to the multi-pin plug (2) of the additional cable.

Connect the socket (3) of the additional cable to the holder of the rear light housing.

Install bulb holders.

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Installation kit - electrical components for trailer coupling BMW 3 Models (E30) - with and without Check-Control

Additional work on cars with Check-Control:

Partly remove the left wheel arch trim.

Run the additional cable along the existing wiring harness.

Remove the control unit.

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Installation kit - electrical components for trailer coupling BMW 3 Models (E30) - with and without Check-Control

Disconnect the multi-pin plug (1) from the control unit and connect to the socket (2) of the additional cable. Connect multi-pin plug (3) of the additional cable to the control unit.

Checking operation:

Connect the negative lead to the battery. Make quite sure that the connections on the plug are the same as the connections in the socket. When a trailer is attached to the towing coupling, make sure that the trailer lights and flashing turn indicators are working properly. The additional repeater light flashes only when a trailer is attached.

Attach all components and trim removed during installation work.

Attach the nose-weight label.

Important:

On cars with additional brake lights, fuse No. 6 (7.5 Amp) must be replaced by a 15 Amp fuse.

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(Circuit diagram without Check-Control)

Installation kit - electrical components for trailer coupling BMW 3 Models (E30) - with and without Check-Control

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Installation kit - electrical components for trailer coupling BMW 3 Models (E30) - with and without Check-Control

Key to electrical circuit diagram

  1. = Cross-section, mm2
  2. = Basic colour
  3. = Identification spiral
  4. = Compartment number
  5. = Terminal designation
  6. = Screw connection (cable shoe)
  7. = Round-pin plug
  8. = Round-pin socket
  9. = Flat-pin plug
  10. = Flat-pin socket
  11. = Solder tag or connector
  12. = Compartment number
  13. = Plug connector designation
  14. = Cables with no cross-section indicated are always 0.75 mm2
  15. = Earth (ground)
E1 Left rear light
E2 Left rear fog light
E3 Left reversing light
E4 Right reversing light
E5 Right rear fog light
E6 Right rear light
H1 Left rear turn indicator
H2 Left brake light
H3 Right brake light
H4 Right rear turn indicator
X1 Plug connector, left main wiring harness for trailer coupling cable
X2 Connection for left rear light
X3 Trailer power socket
X4 Plug connector, right main wiring harness for trailer coupling cable
X5 Connection for right rear light
54 Current path continuation

(see main vehicle electrical circuit diagram)

Colour codes
BL blue
BR brown
GE yellow
GN green
GR grey
RT red
SW black
VI violet
WS white
TR transparent

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Installation kit - electrical components for trailer coupling BMW 3 Models (E30) - with and without Check-Control

Circuit diagram with Check-Control

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Installation kit - electrical components for trailer coupling BMW 3 Models (E30) - with and without Check-Control

Key to electrical circuit diagram

  1. = Cross-section, mm2
  2. = Basic colour
  3. = Identification spiral
  4. = Compartment number
  5. = Terminal designation
  6. = Screw connection (cable shoe)
  7. = Round-pin plug
  8. = Round-pin socket
  9. = Flat-pin plug
  10. = Flat-pin socket
  11. = Solder tag or connector
  12. = Compartment number
  13. = Plug connector designation
  14. = Cables with no cross-section indicated are always 0.75 mm2
  15. = Earth (ground)

E1 Left rear light
E2 Left rear fog light
E3 Left reversing light E4 Right reversing light
E5 Right rear fog light
E6 Right rear light
H1 Left brake light
H2 Left turn indicator
H3 Right turn indicator
H4 Right brake light
X1 Trailer power socket
X2 Plug connector, main wiring harness (bulb tester) for trailer coupling cable (8-pin)
X3 Plug connector, main wiring harness (left rear light) for trailer coupling X4 Connection for left rear light X5 Plug connector, main wiring harness (right rear light) for trailer coupling X6 Connection for right rear light
54 Current path continuation

(see main vehicle electrical circuit diagram)

Colour codes
BL blue
BR brown
GE yellow
GN green
GR grey
RT red
SW black
VI violet
WS white
TR transparent
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