GM3 BCU V4 (SM042V4)

GM3 BCU V4 - System Overview

Borrowed directly from BMW, as the most suitable ECU to modify for the L322 Range Rover application, the GM3 BCU is one in a series of GM variations which controls a large number of different systems throughout the vehicle such as Alarms & Locking, Doors & windows, Wipers and washers.

SM042 - GM3 BCU V4 - System Help file

Version 1.27

GM3 BCU - Known Fitments

Vehicle makes, models and variants known or believed to be using this vehicle system, required diagnostic lead and degree of known compatibility.

Vehicle Make	Vehicle Model	Vehicle Variant	Diagnostic Lead
Land Rover	Range Rover MK III ( L322)	2002 - 2009	Black OBDII Lead/LD020/LD021

GM3 BCU - Physical Details

SM042 - GM3 BCU - Diagnostic Capabilities (Read Fault Codes)

Reads the fault code memory. The ECU can self detect over 140 different problems with itself, its wiring and its associated sensors, storing the respective code if it detects any malfunction or reading outside of pre defined acceptable limits. Not all stored faults may cause the fault warning lamp to illuminate.

SM042 - GM3 BCU - Diagnostic Capabilities (Clear Fault Codes)

Clears the fault code memory.

SM042 - GM3 BCU - Diagnostic Capabilities (Settings)

Values, configuration settings, and other stored information which can be read from the ECU, edited and then rewritten back. Read settings can also be stored as a standard HTML page for reference. These pages can then later be re loaded and re written back to the ECU. Please note that some values may be read only due to the fact that they are supplied from the ECU’s ROM or are internally calculated.

Part Number: This is the manufacturer's part number for the ECU.
Hardware number: This is the hardware version which denotes the processor and circuit board type.
Software number: This is a number which relates to the software programmed in the processor of the ECU.
Supplier number: This is a number which defines the supplier using a standard look up list of supplier of ECU manufacturer.
Coding index: This is a number which denotes the layout of the options within the EEPROM of the ECU and denotes which coding map should be used to program the ECU with.
Diagnostic index: This is a number that indicates the diagnostic capabilities support level.
Bus index: This is a number that indicates the bus communication support level, the vehicle communication buses.
Week of build: This is the week of the year in which the unit was built.
Year of build: This is the year in which the unit was built.
Intensive Wash: Front windscreen intensive wash program, normally disabled on a Range Rover.
Headlamp Power Wash: Denotes if the headlamp power wash is fitted or not fitted.
Front Wiper Pressure Control: Denotes if the front wiper pressure control is enabled or disabled, normally disabled on a Range Rover.
Infra Red Remote On Passengers Door: This denotes if the infra red remote on passenger's door is enabled or disabled.
Passenger Door Key Barrel Disable: This is normally set to enabled whenever a passenger door key barrel is not fitted.
Folding Mirrors: This denotes if the electric folding mirrors are fitted or not fitted.
Heated Mirrors: This denotes if the heated mirrors are fitted or not fitted.
Memory Mirrors: This denotes if the memory for the outside mirrors is either enabled or disabled.
Electric Rear Windows: This denotes if the electric rear windows are enabled or disabled.
Sunroof: This denotes if the sunroof is either fitted or not fitted.
Steering Column Memory: This denotes if the steering column position is either enabled or disabled.
Vehicle Type: Range Rover or other can be selected.
On Board Computer Immobilisation: Status of the on board computer enabled or disabled - normally disabled.
Opening Of Windows With Ignition Off: This function sets the body control to allow opening of window with ignition off.
Interior Lights On With Tailgate Open: This function sets the body control to allow the interior lights to stay on when that tailgate is open.
Speed Locking: This performs automatic self locking of the vehicle if the vehicle exceeds the speed as dictated in the speed locking speed value.
Repeat Speed Locking: This function can be either enabled or disabled. When enabled, the car locks using automatic speed locking. If you unlock it, it will lock again the moment it passes through the set threshold in the speed locking speed value.
Boot Lid/Tailgate Functionality: Set to Saloon or Estate - normally Saloon for Range Rover.
Self Closing Tailgate: This is a feature built into the GM3 Body Control Module when fitted to other vehicles.
Un Superlock With Tailgate Unlock: This denotes if the this feature is enabled or disabled.
Servotronic: This is the speed related power steering sensitivity system, enabled or disabled, normally enabled on a Range Rover.
Signal For Servotronic Source: set to either K Bus or ABS.
Servotronic Type: Range Rover or other.
Servotronic Map Source: ROM or EPROM - EPROM is used for the New Range Rover. The value it is set in the mapping section.
Alarm Arm only When all Panels Closed: This enables or disables alarm arm acknowledgement only when all doors, lids, bonnet are closed.
Wiper Speed Step-down At Standstill: If enabled, the wiper will slow down at standstill. Normally this is disabled if a rain sensor is fitted.
Wiper Interval At Standstill: The wiper interval can be set to either 3 or 5 seconds.
Timed Intermittent Wipe: This function is disabled when a rain sensor is fitted.
Wiper Blade Change: enabled or disabled - when enabled this allows the wiper to be left on the screen when the ignition is turned off and allows the blade to be changed when the system is used on vehicles where the wipers hide behind the rear edge of the bonnet.
Interior Lights Soft On/Off: When enabled, it caused the interior lights to fade in when turned on and when turned off to fade off.
Drivers Seat Memory Outstation Module: This denotes if the function is either fitted or not fitted.
Passengers Seat Memory Outstation Module: This denotes if the function is either fitted or not fitted.
Rear Seat Switch Pack Outstation Module: This denotes if the function is either fitted or not fitted.
Sunroof Outstation ECU: This denotes if the function is either fitted or not fitted.
Hydraulic Boot Opener: This is a function for usage on vehicles supplied with hydraulic boot opening capabilities obviously not the Range Rover.
Key Memory Personalization: This function can be either enabled or disabled. Enabled allows settings to be stored for individual keys.
Single Point Entry For Key 1 to 4: When enabled, unlocking the vehicle the first press will only unlock the driver's door. Unlocking the vehicle with the second press will unlock all doors.
Speed Related Locking for Key 1 to 4: When enabled, locking the vehicle passes through the threshold set in the speed locking value, locking automatically the doors.
Lazy Unlock with Key: When enabled, this allows the user to use the key in the door lock to wind down the windows.
Lazy Lock with Key: When enabled, this allows the user to wind up the windows when locking the car with the key.
Speed Locking Speed Value: This is a value set in kilometres per hour from 0 (instant) in 4 km/h steps to a maximum of 28 km/h.
Driver Window 1 Touch Close: enabled or disabled - When enabled, it allows the window to be closed with one touch letting go. When disabled, it operates in dead mans handle mode with the button being continuously pressed for the window to keep moving.
Driver Window 1 Touch Open: enabled or disabled - When enabled, it allows the window to be opened with one touch letting go. When disabled, it operates in dead mans handle mode with the button being continuously pressed for the window to keep moving.
Passenger Window 1 Touch Close: enabled or disabled - When enabled, it allows the window to be closed with one touch letting go. When disabled, it operates in dead mans handle mode with the button being continuously pressed for the window to keep moving.
Passenger Window 1 Touch Open: enabled or disabled - When enabled, it allows the window to be opened with one touch letting go. When disabled, it operates in dead mans handle mode with the button being continuously pressed for the window to keep moving.
Rear Window 1 Touch Close: enabled or disabled - When enabled, it allows the window to be closed with one touch letting go. When disabled, it operates in dead mans handle mode with the button being continuously pressed for the window to keep moving.
Rear Window 1 Touch Open: enabled or disabled - When enabled, it allows the window to be opened with one touch letting go. When disabled, it operates in dead mans handle mode with the button being continuously pressed for the window to keep moving.
Sunroof 1 Touch Close: enabled or disabled - When enabled, it allows the sunroof to be closed with one touch letting go. When disabled, it operates in dead mans handle mode with the button being continuously pressed for the sunroof to keep moving.
Sunroof 1 Touch Open: enabled or disabled - When enabled, it allows the sunroof to be opened with one touch letting go. When disabled, it operates in dead mans handle mode with the button being continuously pressed for the sunroof to keep moving.
CDL Removes Superlock: When enabled, unlocking using the centre unlocking button unlocks it even in superlocked mode.
Remote Lazy Unlock: When enabled, it allows the user to unlock/wind the window down using the remote control.
Remote Lazy Lock: When enabled, it allows the user to lock/wind the window up using the remote control.
Auto Relock After Two Minutes: When enabled, if the vehicle is unlocked using the remote control and there are no doors or tailgate opened, after two minutes the vehicle will relock but not superlock. The alarm will not be rearmed.
Unlock if Ignition on 30 Seconds After Locking: When enabled, if the ignition is turned on within 30 seconds of locking the doors the locks will unlock.
Interior Light on Repeated Lock Requests: When enabled, the interior lights illuminate with every press on the lock button on the remote or by key.
Unlock with Key if Armed: When enabled, unlocking using the door key is enabled even if the alarm is still armed.
Alarm: The body controls alarm system, either enabled or disabled.
Volumetric Sensor: Enabled or disabled, depending on whether a volumetric sensor is fitted or not.
Tilt Sensor: Enabled or disabled, depending on whether a tilt sensor is fitted or not.
Remote Arming/Disarming: The options are either the remote control only is capable of arming/disarming the alarm, or both key and remote are capable of arming/disarming the alarm.
Alarm Sound: The sound of the alarm, either continuous or intermittent.
Main Beam on Alarm: When the alarm has been triggered, the main beams are used if set to enabled. If set to disabled, the main beam will be not used.
Dip Beam on Alarm: When the alarm has been triggered, the dip beams are used if set to enabled. If set to disabled, the dip beam will be not used.
Hazard on Alarm: When the vehicle has been triggered, the hazards are only used if set to enabled. If set to disabled, the hazards will be not used.
Alarm Arm Acknowledge with Hazards: When enabled, arming the alarm will produce a single flash on the hazards.
Alarm Arm Acknowledge with Horn/Siren: When enabled, this will cause the alarm arm to make a beep on the horn or siren.
Alarm Disarm Acknowledge with Hazards: When enabled, disarming the alarm will produce a single flash on the hazards.
Alarm Disarm Acknowledge with Horn/Siren: When enabled, this will cause the alarm disarm to make a beep on the horn or siren.
Alarm Acknowledge Beep Time Length: This is a value selectable in 10 millisecond increments from 0 to 150 milliseconds, normally set to 80 milliseconds.
Rear Volumetric Sensor: This function is enabled when an additional volumetric sensor is fitted in the rear.
Emergency Disarm: This enables or disables the emergency disarming system.
Alarm Repeats if Trigger Still There: When enabled, the trigger of an alarm if it is still present will cause the alarm to continually re-trigger, otherwise it will trigger just once.
BBUS: The battery back up sounder - either fitted or not fitted.
Automatic Immobilisation: This causes the engine to automatically immobilise after a set period of time.
SPE: This denotes if single point entry is enabled or disabled.
Door Contact Logic: This either ensures a door is closed or open, monitoring the contact when the door is closed.
Anti Trap Reversing: This is the distance the windows reverse when detecting a trap condition and it can be set to either short or long.
Driver's Front Window Anti Trap Monitoring: This enables or disables the anti trap function for this window.
Driver's Rear Window Anti Trap Monitoring: This enables or disables the anti trap function for this window.
Passenger's Front Window Anti Trap Monitoring: This enables or disables the anti trap function for this window.
Passenger's Rear Window Anti Trap Monitoring: This enables or disables the anti trap function for this window.
Window Timer Configuration Type: This is a value which configures the conditions under which the window timer times out. In some markets it times out as soon as the ignition is turned off and in other markets when the driver's door is opened. Normally it is set to 1 in all markets for the Range Rover.
Tailgate Window Anti Trap Monitoring: This is normally disabled on the Range Rover because it does not have an electric opening/closing tailgate window fitted.
Front Door Ajar Input Via: Direct input means that is straight from the switch to the body control module. Outstation is via an external door control unit.
Panic Alarm: The panic alarm is a function where pressing and holding the tailgate to unlock button, the alarm sounds and the hazards warning lamps flash according to their settings.
Trigger Delay for Panic Mode: This is the amount of time the user has to press the remote control tailgate button before the panic mode is engaged where the alarm, siren and illumination activates if set by that feature. This is a value between 0 and 3 seconds.
Number of Engine Cylinders: This is the number of engine cylinders.
K Bus Remote Disable: When enabled, remote control functions are transmitted via the K Bus.
Inhibit Time After Ignition Off: This is a the period of time the remote control cannot be used after the ignition has been switched off. This is a numerical value between 0 and 3 seconds.

E38 FEATURES

Feature 1: enabled or disabled - this is a special feature for E38s only. It is normally disabled on a Range Rover.
Feature 2: enabled or disabled - a specific E38 feature which is enabled on a Range Rover.
Ignition Active in Crash Mode: When a crash has been detected it automatically turns on the ignition.
1 Touch Windows Disabled with Door Open: When the door is open it disables this feature. This function is disabled on a Range Rover.
Feature 4: a specific feature for the E38 - set to disabled on the Range Rover.
Vehicle Options Programmed Flag: This flag must be set on new ECUs to the programmed as opposed to the not programmed option. This indicates to the body control unit that the entire vehicle's options memory is actually valid data as opposed to zeros on a blank ECU.

MAPPING

Servotronic Speed Map: These values are hexadecimal bytes which set up the speed map for the servotronic with default values for Range Rover of: 00, 02 ,0A, 14, 1E, 28, 32, 3C, 46, 50, 5A, 6E, 82, 96, A0, FA. These values must be separated by commas.
Servotronic Speed Map Programmed Flag: This must be set to programmed for the servotronic speed map to be recognised.
Servotronic Current Map: These values are hexadecimal bytes which set up the speed map for the servotronic with default values for Range Rover of: F3, BF, AC, A3, 9A, 92, 8B, 83, 7A, 74, 6E, 5F, 4C, 38, 2D, 1D. These values must be separated by commas.
Servotronic Current Map Programmed Flag: This should be set to programmed as opposed to not programmed to indicate that the servotronic map is current valid data.
Coding Data: A specific block of programmable data stored in the ECU to control its functionality for specific variations of vehicle. There are a number of hexadecimal digits, each digit separated by a comma. Re-entered parameters should be entered in an identical format to that which is read. Changing this values can produce unknown alteration in the functionality of the ECU, damage the ECU, or even damage your car.

SM042 - GM3 BCU - Diagnostic Capabilities (Inputs)

Realtime live display of the information the electronic control unit of the selected vehicle system is currently deriving from its input sensors.

Tailgate Ajar: This shows the current status of the tailgate: open or closed.
Dashboard Mounted Tailgate Release Switch: This shows if the button is pressed or not.
Lower Tailgate Release Switch: This shows if the button on the lower tailgate has been released or not.
Upper Tailgate Release Switch: This shows if the button on the upper tailgate has been released or not.
Bonnet: This shows if the bonnet is closed or not.
Driver's Front Door Ajar: This shows if the driver's door is open or closed.
Passenger's Front Door Ajar: This shows if the passenger's door is open or closed.
Rear Passenger Side Door Ajar: This shows if the rear passenger's side door is open or closed.
Rear Driver Side Door Ajar: This shows if the rear driver's side door is open or closed.
Wiper Park: This shows if the wiper is in park position or not.
Rear Driver's Door Window Switch: This shows the current position of the rear driver's door window switch.
Rear Passenger's Door Window Switch: This shows the current position of the rear passenger door window switch.
Passenger's Door Window Switch: This shows the current position of the passenger's door window switch.
Manual Central Locking Switch: This shows if the button is pressed or not.

DRIVER'S DOOR SWITCH PANEL

Driver's Window Switch: This shows the current position of the driver's door window switch for the driver's door.
Rear Driver Window Switch: This shows the status of the driver's door mounted rear driver window switch.
Rear Passenger Window Switch: This shows the status of the rear passenger's window switch mounted on the driver's door.
Passenger's Window Switch: This shows the current position of the driver's door mounted passenger window switch.
Mirror Switch: This shows the current direction of the mirror direction switch.
Mirror Select: This shows if the mirror switch is selected to passenger's side or driver's side.
Power Fold: This shows if the mirror power fold button is pressed or released.
Rear Window Disable Switch: This shows if the rear window disable switch is on or off.

OTHER

Wiper Switch: This shows if the wipers are on or off.
Intermittent Speed Wipers Switch: This shows if the current selection for the intermittent speed as a numerical value.
Windscreen Wash Switch: This shows if the windscreen wash button is pressed or not.
Power Steering Characteristics: This shows the current status of the servotronic power steering related to vehicle speed.
Any Signal Received: This shows if a signal of the correct frequency is being received.
Key Signal Received: This shows if a signal of the correct frequency for the correct key is being received.
Last Key Used: This shows the number of the key last accepted.
Key Learned: This tells if the key last used was learned to the vehicle by the control module or not.
Key 1 Battery Status: This shows the current status of the battery in Key 1.
Key 2 Battery Status: This shows the current status of the battery in Key 2.
Key 3 Battery Status: This shows the current status of the battery in Key 3.
Key 4 Battery Status: This shows the current status of the battery in Key 4.
Driver's Door Anti Trap Strip: This shows the input of the anti trap strip mounted at the top of the window of the driver's door.
Passenger's Door Anti Trap Strip: This shows the input of the anti trap strip mounted at the top of the window of the passenger's door.
Rear Driver's Door Anti Trap Strip: This shows the input of the anti trap strip mounted at the top of the window of the rear driver's door.
Rear Passenger's Door Anti Trap Strip: This shows the input of the anti trap strip mounted at the top of the window of the rear left passenger's door.
Interior Light: This shows if the interior light button is pressed or released.
Sunroof Switch: This shows the current status of the sun roof switch.
Sunroof Initialise: This shows if the sun roof is initialised or not.
Servotronic PWM %: This shows the current percentage value of the servotronic server motor output.
Power Steering System: This shows the status of the servotronic power steering system related to vehicle speed.
Transmitter Tailgate Button: This shows that if the button on the key fob in use is pressed for the tailgate.
Transmitter Lock/Unlock Button: This shows if the button on the key being used is being pressed for the Lock or Unlock.
Driver's Door Unlock: This shows if the key is being turned to the unlock position.
Driver's Door Lock: This shows if the key is being turned to the lock position.

SM042 - GM3 BCU - Diagnostic Capabilities (Outputs)

A selection of functions and outputs that can be tested. Each output has the option ON and OFF in order to start and stop testing. BECU has control over the following features:

DOORS AND LOCKING

Warning: leaving the locking solenoids energized (on) for more then a few seconds can result in their being permanently damaged.
Upper Tailgate Release: Turn the upper tailgate release solenoid ON or OFF.
Lower Tailgate Release: Turn the lower tailgate release solenoid ON or OFF.
Rear Doors Lock: Turn the rear doors lock solenoid ON or OFF.
Rear Doors Unlock: Turn the rear doors unlock solenoid ON or OFF.
Rear Doors Secure Lock (Superlock): Turn the rear doors secure lock solenoid ON or OFF. This will superlock the rear doors.
Driver's Door Lock: Turn the driver's doors lock solenoid ON or OFF.
Driver's Door Unlock: Turn the driver's doors unlock solenoid ON or OFF.
Driver's Door Secure Lock (Superlock): Turn the driver's doors secure lock solenoid ON or OFF. This will superlock the driver's door.
Passenger's Door Lock: Turn the passenger's doors lock solenoid ON or OFF.
Passenger's Door Unlock: Turn the passenger's doors unlock solenoid ON or OFF.
Passenger's Door Secure Lock (Superlock): Turn the passenger's doors secure lock solenoid ON or OFF. This will superlock the passenger's door.

WINDOWS

Windows: All four windows can be opened and closed. Click on ON to start the movement, and on OFF to stop it.
Caution: make sure that nothing obstructs the window. With the anti trap on, the window should stop winding up when detects an obstruction.
Wipers and Washers: Tests the wipers and washers for the windscreen and headlamp.
Alarm: tests the alarm and alarm's LED.
Driver's Mirror: Possibility to move the driver's mirror up, down. left, right, fold in fold out, or the mirror heater.
Passenger's Mirror: Possibility to move the driver's mirror up, down. left, right, fold in fold out, or the mirror heater.

SM042 - GM3 BCU - Diagnostic Capabilities (Other)

Choice of functions that can be performed.

Read Transport Mode: This allows the current transportation mode to be verified.
Set Transportation Mode: This allows the transportation mode to be set. Make sure that the vehicle is not central locked or super locked. By setting the body control in transport mode, the ECU will store a fault. where the vehicle will no longer adjust its height.
Clear Transport Mode: This allows the transport mode lock to be cleared. Make sure that the vehicle is not central locked or super locked. Clearing the transport mode will not clear the fault code in the BCU memory. As long as the faults remain in the memory, the ECU will be reported as in transport mode.