Land Rover Defender: Towbar - Operation

DEPLOYABLE TOWBAR

The deployable towbar operates when the vehicle is stationary and the selected transmission gear position is PARK or NEUTRAL.

Press the deployable towbar switch to deploy the towbar. When the towbar is operating, an audible warning is emitted from the deployable towbar speaker. The LED warning indicator on the deployable towbar switch flashes slowly when the towbar is operating. When the deployable towbar is fully deployed, the audible warning stops and the LED warning indicator is permanently illuminated. The purpose is to indicate that the towbar has deployed and locked correctly.

When the deployable towbar is deployed, press the deployable towbar switch to stow the towbar under the vehicle.

The LED warning indicator extinguishes after 2 seconds when the towbar is fully stowed.

Press the deployable towbar switch to stop movement of the deployable towbar at any time. Press the switch again to reset the towbar to the deployed position.

When an obstruction occurs during deployment of the deployable towbar, the towbar movement stops. The LED warning indicator flashes faster, accompanied by an audible warning sound. When the obstruction has been cleared, operate the deployable towbar switch to reset the towbar.

When the vehicle is put in gear or moves and the towbar is not fully locked, the warning sound occurs. The sound does not depend on a trailer being present.

NOTE: Do not tow with the vehicle when the powered towbar is not fully deployed. When this action does occur, a warning sound is audible for 10 seconds.

In the event of an unexpected operation, pressing the deployable towbar switch resets the towbar. During the reset operation, the deployable towbar completes a full stow and deploy cycle.

The user also can operate the deployable towbar on the FCDIM.

The following functions of deployable towbar are available on the FCDIM menu:

• Stow
• Deploy
• Stop
• Recover
• Lamp test
• Nose load measurement.

The FCDIM shows the current towbar status and the warning signs for faults and obstructions. The FCDIM communicates with the BCM/ GWM on the HS CAN Human Machine Interface (HMI) systems bus. The BCM/ GWM transmits the signals to the TBM on the HS CAN body systems bus.

DEPLOYABLE TOWBAR WARNING INDICATOR

The TBM is able to communicate various status and fault indicators through the warning indicator on the deployable towbar switch.

Details of the warning indicator codes are shown in the following table:

TRAILER LAMP TEST SWITCH

A trailer lamp test switch is located beside the deployable towbar switch. A single press of the trailer lamp test switch initiates a 3 minute sequence, testing both the vehicle and trailer lamps.

When initiating the trailer lamp test, all the vehicle lamps and ignition must be switched OFF and the Electric Park Brake (EPB) must be engaged. During the trailer lamp test, each trailer lamp and the corresponding vehicle lamp operates in turn.

The 3 minute test sequence can be stopped by any of the following actions:

• Operate the trailer lamp test switch.
• Turn the vehicle lamps ON.
• The ignition switch is in Power Mode 6 (ignition ON).

OVERUSE PROTECTION

The overuse protection is used to prevent the towbar motors from overheating. The temperature is estimated by the TBM. When the temperature is over the programed value further operation of the deployable towbar is inhibited when the deployable towbar has reached the deployed position. When the overuse protection is active, the LED warning indicator flashes briefly when the deployable towbar switch is pressed.

It is safe to tow with the towbar in the inhibited condition.

The deployable towbar motors cool down fully in 90 minutes, irrespective of if the vehicle is used or not. No further action is required and normal operation is restored.

TRAILER LOAD CHECK

The trailer load check is performed every time when the deployable towbar stows the towbar arm. The TBM initiates a sequence to detect if there is any load on the towbar arm. The purpose is to determine if the trailer is connected.

When the TBM detects a load, the stow operation is canceled.

NOSE LOAD MEASUREMENTS

When the towbar is deployed, the nose load that the trailer is putting on the towbar can be measured. The measurement is initiated from the FCDIM.

The conditions for measuring the load are the following:

• The vehicle is in NEUTRAL or PARK and is not moving.
• The vehicle is on level ground.
• The temperature is in the range -20ºC (-4ºF) to 60ºC (140ºF).
• The normal suspension height is selected.

The trailer nose load is measured by slightly unlocking and then relocking the towbar. The current taken to relock the towbar is accurately measured and the load calculated from that. The TBM sends a load signal to the FCDIM and the load is shown to the user. A range is displayed to allow for the tolerance in the readings.

When the load is very small or the trailer is pulling upwards on the towbar arm, the FCDIM shows 'less than 25 kg'.

The deployable towbar cannot measure upward loads. When the load is very large, the FCDIM shows 'more than 200 kg'. The deployable towbar cannot accurately measure very large loads.

DIAGNOSTICS

The TBM records any DTCs and related data. Read the DTCs and related data with the JLR approved diagnostic equipment.

The JLR approved diagnostic equipment can read live data and activate certain components.

CONTROL DIAGRAM

CONTROL DIAGRAM - 1 OF 1

A = HARDWIRED: AZ = HS CAN BODY SYSTEMS BUS: BA = HS CAN HMI SYSTEMS BUS.

1. TBM
2. FCDIM
3. BCM/ GWM
4. Trailer socket
5. LED warning indicator - Deployable towbar
6. Deployable towbar speaker
7. Deployable towbar mechanism
8. Ground
9. Power supply
10. Hall effect sensor - Deployable towbar mechanism (quantity 4)
11. Deployable towbar and trailer lamp test switch

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