Antitheft System - Inadvertent Alarm Activation
NO.86/03/96/US
DATE
9/16/96
SUBJECT
Inadvertent Alarm Activation-Associated with Front Door Latches
MODEL
Range Rover 4.0/4.6
AFFECTED VEHICLES
LP 300190-309000
DETAIL
Reports have identified a number of system alarm concerns relating to incorrect door open messages.
The items on the following list are known symptoms associated with door latch electrical faults:
1. Alarm sounds followed by message display showing "alarm triggered bonnet" when ignition turned on.
2. Door open message when door closed.
3. Alarm sounds followed by message showing "alarm triggered X door".( X = defined door on message center).
4. Central door locking buttons jump up and down.
5. Alarm sounds when opening door after unlocking with mechanical key.
6. Battery goes dead.
ACTION REQUIRED
Upon customer complaint of inadvertent alarm activation, the information provided below will assist in diagnosis of specific door latch problems.
PARTS INFORMATION
ALR6954, ALR6958 - Right hand door
ALR6955, ALR6959 - Left hand door
WARRANTY
Not Applicable.
COMP. CODE
Not Applicable
SRO
Not Applicable
PROCEDURE
Item 1, This problem can be caused either by a faulty front door latch or hood switch circuit If the customer has not seen any incorrect hood open messages while driving the vehicle then its unlikely that the fault is caused by the hood switch circuit If it is not thought to be associated with the hood switch then ensure both front latches are to the latest type.
NOTE: This failure mode can also prevent the BeCM from going into sleep mode and can result in the battery going dead.
Item 2, This problem can be caused either by a faulty door latch, out station (front doors only), or a short to ground on the purple/white wire for that particular door. If a door open message is permanently displayed, remove the door trim pad, inspect the purple/white wire in the door for chaffing or being trapped. If the wire is okay, close the door and remove the 6 way connector from the door latch. If the message disappears the door latch is faulty.
Repeat to confirm the latch fault. If the message remains, the fault is a trapped wire (on rear doors check this wire back to the BeCM) or an outstation fault. If the door open message is intermittent, remove door trim and inspect this wire for damage. If wire is okay, replace the door latch.
Item 2, As item 2 (treat as an intermittent fault).
Item 4, (Sill buttons lock and unlock by themselves). This can be caused by a faulty front door latch, an intermittent open circuit or short to ground on the green/red wire. On the door that has the fault, if the sill button will not lock or unlock, check the green/red wire which is located in the front door between the door latch and the outstation in both front doors. On the right hand front door this wire also extends from the outstation to the lower tailgate release button. An intermittent short to ground on this wire can cause an unrequested locking and unlocking of the central door locking. If the wiring is okay, replace the door latch that did not lock and unlock.
Item 5, Caused by either a faulty drivers door latch, outstation or door harness. The BeCM which controls the alarm system is looking for the correct sequence of signals from the door latch, otherwise the alarm will go off when the door is opened. Check the signals, 5 Volts when open and 0 Volts when closed, on the blue/red wire (key switch) and the green/red wire (central door locking switch) at the outstation in the drivers door. If the signals are incorrect (see diagram 1) then replace the faulty component or repair harness. If the signals are correct, then the vehicle may have a drivers door latch on the front passenger door and may prevent the BeCM from operating correctly. To determine if this is the case, disconnect battery and disconnect both front passenger door harness connectors inside 'A' post (remove door to 'A' post grommet at 'A' for access), wait 30 seconds before reconnecting the battery. If the alarm no longer sounds when unlocking and opening drivers door then replace front passenger door latch with correct part.
Item 6, See item 1.
NOTE: When replacing latch ensure latch is the latest type (i.e date code for front and rear latch is between >031 and 365). Date code can be found on the jaws of the latch (stamped into plastic).
(SEE ILLUSTRATION)- The latest front latch can be identified by a single pin in the 2 way connector housing.
The extract from the Electrical Trouble Shooting Manual provided on the following page shows the electrical circuit for a right hand front door. A left hand front door latch has the same circuit except the wire locations in the 6 way latch connector are different Rear doors do not have outstations and the latches are wired directly to the BeCM and only have a door ajar switch.
When the central door locking switch, key switch or door ajar switch is open (as shown in diagram 1), then the voltage on the wire to the outstation for that switch will be 5 Volts. When the switch is closed the voltage on that wire will drop to 0 Volts.
When central door locking button is down the central door locking switch is open. (green/red wire)
The key switch is open when the key is not turned in either the lock or unlock direction. (blue/red wire)
The door ajar switch is open when door is dosed. (purple/white wire)
For rear doors the door ajar switch's voltage (when open) will be 12 Volts. For front doors the switch will be open (5 Volts) when the front door is closed.