Land Rover Defender: Towbar - Description

DESCRIPTION

DEPLOYABLE TOWBAR

NOTE: Vehicle with 5 doors is shown, vehicle with 3 doors is similar.

1. Deployed position
2. Stowed position

1. Electrical connector (quantity 2)
2. Cross beam
3. Trailer socket
4. Towbar arm
5. Deployable towbar mechanism

The deployable towbar comprises a fabricated steel cross beam which replaces the armature located behind the rear bumper cover. The cross beam is attached at each end to the vehicle body with 16 bolts and washers. The bolts are screwed into threaded holes in the vehicle body.

A pair of brackets are welded centrally on the cross beam. The deployable towbar mechanism is located between the brackets and secured with 7 bolts. The deployable towbar arm comprises of the ball arm and the ball.

The trailer socket is attached to the deployable towbar arm with 2 bolts. The trailer socket moves together with the deployable towbar arm during the deploying and stowing process.

DEPLOYABLE TOWBAR MECHANISM

1. Gear and lock housing
2. Trailer socket
3. Bolt (quantity 7)
4. Boot
5. Motor housing
6. Electrical connector
7. Breakaway cable attachment point
8. Towbar arm

The deployable towbar mechanism comprises 2 motors and the towbar arm assembly.

The first motor controls the stow and deploy movement functions. The second motor controls the locking and unlocking of the towbar arm.

DEPLOYABLE TOWBAR MOTOR - STOW/DEPLOY

NOTE: The procedure contains some variation in the illustrations depending on the vehicle specification, but the essential information is always correct.

1. Towbar arm
2. Towbar arm gear
3. Motor gear
4. Deployable towbar motor - Stow/deploy
5. Deployable towbar motor - Lock/unlock

The deployable towbar motor - Stow/deploy has a tapered gear wheel attached to the motor spindle. The gear wheel meshes with gear teeth on the towbar arm. The gear teeth on the towbar arm are shaped in a way that which rotates and lowers the towbar arm as the motor operates. The deployable towbar motor - Stow/deploy is controlled by the TBM

The deployable towbar motor - Stow/deploy contains 2 Hall effect position sensors. The position sensors are used by the TBM to determine the position of the towbar arm. When the towbar arm approaches either the stowed or deployed positions, the TBM detects the position and stops the deployable towbar motor - Stow/deploy.

DEPLOYABLE TOWBAR MOTOR - LOCK/UNLOCK

NOTE: The procedure contains some variation in the illustrations depending on the vehicle specification, but the essential information is always correct.

1. Towbar arm locked position
2. Towbar arm unlocked position

1. Deployable towbar motor - Lock/unlock
2. Locking blocks (quantity 2)
3. Deployable towbar motor - Stow/deploy

The deployable towbar motor - Lock/unlock operates a threaded spindle. The spindle has a left and a right threaded locking blocks which move along the 2 threads on the spindle. The 2 threads drive the locking blocks in opposite directions when the deployable towbar motor - Lock/unlock is operated. The locking blocks are engaged or disengaged with the grooves on the towbar arm.

The deployable towbar motor - Lock/unlock contains 2 Hall effect position sensors. The position sensors are used by the TBM to determine the position of the locking blocks.

The position of the locking blocks when unlocking is monitored by the TBM using the following:

• The current measurement of the deployable towbar motor - Lock/unlock.
• The pulses from Hall effect position sensors.

The deployable towbar motor - Lock/unlock is operated, driving the locking blocks to the outer sides of the motor housing. When the locking blocks become near to the end of the spindle, the TBM stops the deployable towbar motor - Lock/unlock. Then the TBM operates the deployable towbar motor - Lock/unlock to deploy the towbar arm.

When the towbar arm moves to the deployed position, the TBM determines that the towbar arm is in the fully deployed position. The TBM uses the pulses from the position sensors. When the fully deployed position is reached, a mechanical catch holds the towbar in the deployed position and the TBM initiates locking.

The TBM operates the deployable towbar motor - Lock/unlock, which rotates the spindle. The spindle moves both locking blocks towards the center of the spindle. The TBM monitors the current rise in the deployable towbar motor - Lock/unlock and measures the pulses from the position sensors. The TBM determines that the towbar arm is fully locked.

The above procedure is repeated for both stow and deploy functions.

TOWBAR CONTROL MODULE

NOTE: Vehicle with 5 doors is shown, vehicle with 3 doors is similar.

The TBM is located in the loadspace, behind the loadspace floor trim panel. The TBM is located on 2 studs and secured with nuts.

All functions of the deployable towbar are controlled by the TBM which responds to user requests for stow and deploy from the deployable towbar switch. A Light Emitting Diode (LED) warning indicator on the deployable towbar switch is controlled by the TBM. The warning indicator is illuminated in various ways to advise the user that the towbar is operating correctly or a fault condition exists.

The TBM also controls the deployable towbar speaker, providing the user with audible warnings to advise on towbar operating or fault conditions.

Power supply for the TBM is through a fused connection from the rear junction box. The TBM is connected to the vehicle electrical system on the HS CAN body systems bus.

The Diagnostic Trouble Code(s) (DTC)s are stored in the TBM and can be read using the Jaguar Land Rover (JLR) approved diagnostic equipment.

The TBM is able to communicate various status and fault indicators through the following:

• An audible warning from the deployable towbar speaker.
• The LED warning indicator on the deployable towbar switch.

DEPLOYABLE TOWBAR SPEAKER

NOTE: Vehicle with 5 doors is shown, vehicle with 3 doors is similar.

The deployable towbar speaker is located in the loadspace, behind the loadspace floor trim panel. The speaker is attached to the TBM bracket with 2 cross bolts and nuts.

The deployable towbar speaker is connected to the TBM through hardwired connection. The TBM uses the deployable towbar speaker to give audible warning to the user when:

• The deployable towbar is operating.
• There is a system fault.

DEPLOYABLE TOWBAR AND TRAILER LAMP TEST SWITCH

NOTE: Vehicle with 5 doors is shown, vehicle with 3 doors is similar.

1. LED warning indicator
2. Deployable towbar switch - Stow/deploy
3. Trailer lamp test switch

The deployable towbar and trailer lamp test switch is located in the left loadspace trim panel. The switch is a press fit and secured with spring clips.

The switch is connected to the TBM directly through hardwired connection. The connections are for switch illumination, LED warning indicator, stow/deploy selection, trailer lamp test selection and ground. The ground is connected back to the TBM.

The trailer lamp test switch allows the vehicle lamps and the trailer lamps to be checked for correct operation by the user without assistance.

The deployable towbar switch has an LED warning indicator which is controlled by the TBM. The TBM can illuminate the warning indicator in a number of ways to provide visual indication to the user when:

• The deployable towbar is operating.
• There is a system fault.

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