Land Rover Defender: Seatbelt System - Diagnosis and Testing

DIAGNOSIS AND TESTING

PRINCIPLE OF OPERATION

For a detailed description of the seatbelt system and operation, refer to the relevant description and operation section of the workshop manual.

SAFETY INFORMATION

WARNINGS:

• To avoid accidental deployment the back-up power supply must be depleted before beginning any work on the SRS system or its components. Failure to follow this instruction may result in personal injury.
• Do not use a multimeter to probe an SRS module. It is possible for the power from the multimeter battery to trigger the activation of the module. Failure to follow this instruction may result in personal injury.

NOTE: Do not to use a mobile phone or to have a mobile phone in close proximity when working on the SRS system or components.

Power supply depletion

Before beginning any work on the SRS system or related components:

1. Remove the ignition key
2. Disconnect the battery leads, ground first
3. Wait 1 minute for the power circuit to discharge

There are comprehensive instructions on the correct procedures for SRS system repairs, refer to the relevant section of the workshop manual

INSPECTION AND VERIFICATION

CAUTION: Diagnosis by substitution from a donor vehicle is NOT acceptable. Substitution of control modules does not guarantee confirmation of a fault, and may also cause additional faults in the vehicle being tested and/or the donor vehicle.

NOTES:

• The 'car sense system' of the seatbelt is sensitive to both cornering and braking forces and is designed to lock when it detects this. It is therefore possible to lock when parking the vehicle on high kerbs and inclines. The seatbelt retractor will be locked when removed from the vehicle as it is not in the exact orientation that it was installed on the vehicle. This can be mistaken as a jammed seatbelt retractor.
• If a control module or a component is at fault or may be at fault and the vehicle remains under manufacturer warranty, refer to the Warranty Policy and Procedures manual, or determine if any prior approval program is in operation, prior to the installation of a new module/component.
• When performing voltage or resistance tests, always use a digital multimeter that has the resolution ability to view 3 decimal places. For example, on the 2 volts range can measure 1mV or 2 K Ohm range can measure 1 Ohm. When testing resistance always take the resistance of the digital multimeter leads into account.
• Check and rectify basic faults before beginning diagnostic routines involving pinpoint tests.

1. Verify the customer concern by operating the seatbelt
2. Visually inspect for obvious signs of mechanical or electrical damage. Additionally inspect the seatbelt webbing and upper D-loop for signs of dirt/contamination

Visual Inspection

3. If an obvious cause for an observed or reported concern is found, correct the cause (if possible) before proceeding to the next step
4. If the cause is not visually evident, complete the test methods described below, alternatively check for diagnostic trouble codes and refer to the relevant diagnostic trouble code index

Lap belt (anchor point) pretensioner webbing check

Refer to the 501-20 removal and installation section of the workshop manual, remove any trim panels required to expose the lap belt (anchor point) pretensioner.

Be careful not to remove the webbing pin from the loop of the webbing. Make sure that the webbing pin is installed correctly inside the loop of the webbing with the webbing pin and the loop slotted into the assembly.

SYMPTOM CHART FOR SEATBELT ROWS 1, 2 AND 3

INERTIA REEL SEATBELTS

The vehicle is equipped with (two row one), (three row two), and (two row three (seven seat versions only) ) inertia reel seatbelts These seatbelts are "dual sensitive" which means that they have:

• Car sense system - A vehicle motion sensor, which locks the seatbelt webbing under braking, cornering, on steep hills and in adverse camber conditions, when parked on a steep incline or driveway or two wheels on a high pavement. When the seatbelt retractor is removed from the vehicle and not oriented at the exact angle that it is installed in the vehicle, on level ground, it will be locked. This can be mistaken as a jammed seatbelt retractor.
• Web sense system - A webbing motion sensor, which locks when the seatbelt webbing is extracted suddenly

The seatbelts in the following positions are equipped with an automatic locking retractor function:

The automatic locking retractor function is a feature to secure a child seat or heavy load to the seat

SEATBELT LOCKING TEST

With the vehicle stationary and on level ground take firm hold of the seatbelt webbing (on the tongue side of the upper seatbelt anchor) and withdraw sharply, the retractor should lock. Preventing further webbing release (repeat this test 3 times). Any seatbelt retractor which fails to lock must not be used and a new seatbelt must be installed.

DIAGNOSTIC GUIDE INERTIA REEL SEATBELTS

PINPOINT TEST A : BACKLOCK

PINPOINT TEST B : WEBBING - TRAPPED IN SEAT

PINPOINT TEST C : SEATBELT RETRACTOR - WEBBING GUIDE LOOSE

PINPOINT TEST D : TWIST IN WEBBING

PINPOINT TEST E : INTERFERENCE - WEBBING ROUTING

PINPOINT TEST F : SEATBELT RETRACTOR - INCORRECT INSTALLATION

PINPOINT TEST G : D-LOOP NOT ROTATING CORRECTLY

PINPOINT TEST H : SEATBELT BUCKLE - NOT LATCHING/JAMMED

PINPOINT TEST I : SEATBELT SLOW RETRACTION

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