GM6 BCU - System Overview
The GM6 BCU is, like the earlier GM3 BCU taken directly from the BMW stable and converted to suit a different model. In this case all Rover 75. A very sophisticated and integrated unit, it controls a large variety of different sub systems throughout the vehicle such as Alarms & Locking, Doors & windows, Wipers and washers.

There are two different versions of the GM6 ECU, a high line and a Low Line and visually they are identical except for the colour, the low line (pictured ) is near white and the high line is near black. Functionally they are identical with the exception that the high line one has the capability to operate electric windows in the rear of the vehicle
SM078 - GM6 BCU - System Help file
Version 1.22

GM6 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
Rover 75 All Models Black OBDII Lead
Rover 75 Tourer All Models Black OBDII Lead
MG ZT All Models Black OBDII Lead
MG ZTT All Models Black OBDII Lead

GM6 BCU - Physical Details

GM6 BCU - Pin Outs
Details of the pin usage for the ECU connector(s).

 
1 Driver's lock motor
2 Boot release actuator
3 Right rear window anti-trap
4 Left rear window anti-trap
5 Passenger window down
6 Front wiper slow/fast relay
7 BBUS arm/disarm
8 Right rear door open switch
9 Driver's door open switch
10 Driver's door key lock switch
11 Logic earth
12 Sound alarm
13 Intermittent wiper delay potentiometer
14 Heated rear window relay
15 Alarm RF receiver +12V
16 Front wiper speed feedback
17 Master unlock switch
18 K Bus 1
19 Not used
20 Driver's window anti-trap
21 Passenger window anti-trap Input
22 Not used
23 Passenger window up
24 RF code in
25 Left rear door open switch
26 Passenger door open switch
27 Driver's door key unlock switch
28 Inertia switch OK signal
29 Auxiliary sense (Fuse 8)
30 Front washer pump
31 Ultrasonics in
32 Not used
33 Driver's window switch bus link
34 Front wiper run/park relay
35 Master lock switch
36 Alarm sensors switched +12V
37 Left rear window down
38 Left rear window up
39 Right rear window down
40 Right rear window up
41 Alarm LED
42 Horn/headlamp power wash
43 Not used
44 Boot release switch
45 Bonnet open switch
46 Interior light switch
47 Boot open switch
48 Boot key barrel switch
49 Column switch 2
50 Column switch 1
51 - 52 Not used
53 Front wiper park switch
54 Logic power (battery supply)

 
1 Not used
2 Recalculated air
3 Evaporator temperature thermistor
4 Air conditioning switch LED
5 Heated rear window switch LED
6 Recirculation switch LED
7 Heated rear window switch
8 Recirculation switch
9 Air conditioning switch
10 Fresh air
11 Heater blower relay
12 Pollution sensor
13 Driver's window down switch (hardwired)
14 Driver's window up switch (hardwired)
15 Spare 2
16 Spare 1
17 Heater blower motor sense
18 K Bus 2

 
1 Interior light power VBatt
2 CDL power V Batt
3 Power earth
4 Motor common relay
5 Front window earth
6 Passenger window 2
7 Front window power V Batt
8 Rear window earth
9 Left rear window 1
10 Rear window power VBatt
11 Glove box, vanity mirror lamps
12 Interior lamps
13 Superlock motor relay
14 Passenger and rear doors motor relay
15 Driver's window 2
16 Driver's window 1
17 Passenger window 1
18 Left rear window 2
19 Right rear window 2
20 Right rear window 1

SM078 - GM6 BCU - Diagnostic Capabilities (Read Fault Codes)
There is a choice of reading codes from 3 different memory stores, a traditional fault code memory, a mislock memory and an Alarm trigger event memory.

Fault Codes
The system can self detect up to 49 different problems with itself and 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.
Alarm Trigger events
There are 15 different causes of the alarm activating and this function reads a list of the cause on each occasion for the last 15 occasions, with the oldest cause being shown first and the most recent being the last shown.
Mislock Events
There are 15 different causes of a mislock and this function reads a list of the cause on each occasion for the last 15 occasions, with the oldest cause being shown first and the most recent being the last shown.

SM078 - GM6 BCU - Diagnostic Capabilities (Clear Fault Codes)
This gives a choice of clearing the fault code memory, the mislock cause memory or the Alarm trigger event memory.

SM078 - GM6 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.

This gives 3 choices, General settings and information, Read ECU data to Map file and Program ECU with data from map file.
The read ECU data to Map file and Program ECU with data from map file functions allow you to save data from any ECU as a MAP file and re use it at any time to re program any new or used ECU. The General settings and Information allows values, configuration settings and other stored information, to 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.

GENERAL SETTINGS AND INFORMATION
  • Part Number: This is the part number for the ECU.
  • Supplier Number: This is a number which defines the supplier using a standard look up list of supplier ECU manufacturer numbers.
  • Hardware Number: This is the hardware version which denotes the processor and circuit board type.
  • Software Number: This denotes the coding inside the processor for the hardware.
  • Coding Index: This is the coding identification for the programming maps.
  • Diagnostic Index: This is a number that indicates the diagnostic capabilities support level.
  • BUS ID: Identifies the bus communication support level, the vehicle communication buses.
  • Manufacturing Week: Gives the week in which the unit was built.
  • Vin Number: Gives the car VIN number.
  • Plips: All key fobs come new with an attached label bearing a long number at the top, a striped bar code in the middle and another long number at the bottom. These two numbers are referred to as upper and lower bar codes and uniquely identify the fob electronically via its transmitted code. The upper bar code is 18 digits long and the lower is 17 digits long. Both numbers begin and end with stars, which are also often called asterisks.
  • Plip 1: Barcode 1 - Upper Barcode on Plip.
  • Plip 1: Barcode 2 - Lower Barcode on Plip.
  • Plip 1: Status - Enabled or Disabled.
  • Plip 2: Barcode 1 - Upper Barcode on Plip.
  • Plip 2: Barcode 2 - Lower Barcode on Plip.
  • Plip 2: Status - Enabled or Disabled.
  • Plip 3: Barcode 1 - Upper Barcode on Plip.
  • Plip 3: Barcode 2 - Lower Barcode on Plip.
  • Plip 3: Status - Enabled or Disabled.
  • Plip 4: Barcode 1 - Upper Barcode on Plip.
  • Plip 4: Barcode 2 - Lower Barcode on Plip.
  • Plip 4: Status - Enabled or Disabled.
  • Plip 5: Barcode 1 - Upper Barcode on Plip.
  • Plip 5: Barcode 2 - Lower Barcode on Plip.
  • Plip 5: Status - Enabled or Disabled.
READ ECU DATA TO MAP FILE
This function reads the entire memory of the ECUand it stores on the server in a file that starts with GM6.

PROGRAM ECU WITH DATA FROM MAP FILE
Clicking on this link causes the vehicle explorer to communicate with the Vehicle Server to obtain a list of all of the map files on the vehicle server which can be programmed into the ECU. It will then automatically open the following page:
  • PROGRAM SELECTED MAP TO ECU
    You must program a valid ECU map. To program a map, select, from the drop down menu, the map that you want to use to program into the ECU and then click on the button itself around the list box. The Vehicle Server will start programming the ECU and give you a status report of progress as it does so. The system automatically verifies that they are maps for the GM6BCU ECU and suitable for the ECU's coding index.

SM078 - GM6 BCU - Diagnostic Capabilities (Inputs)
Constantly updating display in HTML of real time information the electronic control unit of the selected vehicle system is currently deriving from its input sensors and switches. These displays can be saved as HTML snap shots, recorded as an AVI movie or captured as A CSV data file for import into a spread sheet program such as Excel.

  • Wiper Feedback: Gives the percentage value of the wiper feedback. (Nominal values: <10% = off. 10% - 60% = slow up to intermittent. 60% - 80% = fast).
  • Intermittent Speed Wiper Switch Wiper Intermittent Speed Short Circuit/Speed 1/Speed 2/Speed 3/Speed 4/Open Circuit.
  • Wiper Park Sense: Gives the state of the BCU wiper park sense. Wiping or Park.
  • Column Switch: Gives the state of the BCU wiper column switch. Off, Intermittent, Slow, Fast or Flick.
  • Wash Pump Switch: Gives the state of the BCU wash pump switch. On or Off.
  • Lamp Power : Gives the state of the BCU lamp power On / Off.
  • Interior Light: Gives the state of the BCU interior light On/Off.
  • Window Power: Gives the state of the BCU Window Power. On or Off.
  • Passenger Window Down Switch: Gives the state of the BCU passenger window down switch. Pressed or Released.
  • Passenger Window Up Switch: Gives the state of the BCU passenger window up switch. Pressed or Released.
  • Passenger Window Down Relay: Gives the state of the BCU passenger window down relay. On or Off.
  • Passenger Window Up Relay: Gives the state of the BCU passenger window up relay. On or Off.
  • Driver Window Down Relay: Gives the state of the BCU driver window down relay. On or Off.
  • Driver Window Up Relay: Gives the state of the BCU driver window up relay. On or Off.
  • Rear Right Window Down Switch: Gives the state of the BCU rear right window down switch. Pressed or Released.
  • Rear Right Window Up Switch: Gives the state of the BCU rear right window up switch. Pressed or Released.
  • Rear Left Window Down Switch: Gives the state of the BCU rear left window down switch. Pressed or Released.
  • Rear Left Window Up Switch: Gives the state of the BCU rear left window up switch. Pressed or Released.
  • Rear Right Window Down Relay: Gives the state of the BCU rear right window down relay. On or Off.
  • Rear Right Window Up Relay: Gives the state of the BCU rear right window up relay. On or Off.
  • Rear Left Window Down Relay: Gives the state of the BCU rear left window down relay. On or Off.
  • Rear Left Window Up relay: Gives the state of the BCU rear left window up relay. On or Off.
  • Drivers Window Down: Gives the state of the BCU driver’s window down switch. On or Off.
  • Drivers Window Up: Gives the state of the BCU driver’s window down switch. On or Off.
  • Passengers Window Down: Gives the state of the BCU passenger window down switch. Pressed or Released .
  • Passengers Window Up: Gives the state of the BCU passenger window up switch. Pressed or Released.
  • Rear Right Window Down: Gives the state of the BCU rear right window down switch. Pressed or Released.
  • Rear Right Window Up: Gives the state of the BCU rear right window up switch. Pressed or Released.
  • Rear Left Window Down: Gives the state of the BCU rear left window down switch. Pressed or Released.
  • Rear Left Window Up: Gives the state of the BCU rear left window up switch. Pressed or Released.
  • Rear Disable: Gives the state of the BCU rear disable switch. Pressed or Released.

SM078 - GM6 BCU - Diagnostic Capabilities (Outputs)
Choice of outputs that can be tested. The outputs would be pulsed.

  • Driver Window Close: Forcing this output closes the driver window.
  • Driver Window Open: Forcing this output opens the driver window.
  • Passenger Window Close: Forcing this output closes the passenger window.
  • Passenger Window Open: Forcing this output opens the passenger window.
  • Rear Right Window Close: Forcing this output closes the rear left window.
  • Rear Right Window Open: Forcing this output opens the rear right window.
  • Rear Left Window Close: Forcing this output closes the rear left window.
  • Rear Left Window Open: Forcing this output opens the rear left window.
  • Heated Rear Window: Forcing this output turns the rear window heater on.
  • Wiper Enable: Forcing this output activates the wiper run/park relay.
  • Wiper Fast: Forcing this output activates the wiper fast/slow relay. In order to force the fast/slow relay, the run/park relay (wiper enable) must be run first.
  • Interior Light: Forcing this output turns the interior light on.
  • Map light: Forcing this output turns the map light on.

SM078 - GM6 BCU - Diagnostic Capabilities (Other)
  • Plip receiver test: This test allows any PLIP (Key Fob) of the correct frequency to be used too Lock and Unlock the vehicle allowing correct operation of the RF receiver circuit to be verified.