Navigation Unit Details

Here are some interesting facts I just found out on the E38 Navigation System unit:

Left side of trunk, left to the CD Changer. Below the Navigation CD Reader.

To get access to it, first remove the Navigation CD Reader by plugging in the Philps "hooks" into the holes of the reader. If you don't have this specific tools, you can also insert some nails. They will bend the clamps of the unit so that you can draw it out. Remove the cables. The coax cable also is only plugged, no wrench needed. After that, unclip the plastic frome of the Navi CD reader. Then remove left trunk cover. Unplug the naviagtion unit (again, all coax connectors are only plugged. Remove them with gentle force).

2 small coax cables - the TV diversity antennas
1 big coax calble - the CAN bus
1 blue connector - power supply and control wires
1 white connector - In total 4 black cables: the audio/video in/out

For all of you who are looking for the famous AV option, here are the connectors located! If you don't have these AV connectors then -in case you want to run an extra DVD player or Video- you surely have to access this white connector. Here is the pinning of the blue (X18804) & white (X18806) connector at the Video module. The first two tables should be valid for the older versions, the other one for the newer cars.

In my car cables are attched to the white connector of the Video module. The lead to the AV in/out jacks in the back of the passenger compartment (under the ventilation unit for the rear passengers).

Components inside:
Oops, lot of ICs. What I was able to see after opening it and removing the metal protection shields inside (a few devices could not be identified as they were coated with some kind of passivation paint):
Name Manufacturer Description assumed function
SCC68070 Philips 16/32 bit CMOS MPU Main processor
SCC68470 Philips I/O module Interface to all other modules
4 x N28F020 ?? 2 Mbit Flash Eprom Software program memory
HYF514... Siemens RAM Processor Memory
COM20020 SMC CAN bus controller / Arcnet CAN bus interconnection
TDA8451 Philips P2CC Delay Line and Matrix TV PAL decoder
TDA8452 Philips ??
TDA8466 Philips ???
TDA8490 Philips SECAM decoder SECAM TV reception
SAA9042 Philips Teletext Videotext (TV Text, Teletext)
SAA 5191 Philips Teletext Video Processor Videotext (TV Text, Teletext)
MB81C514256 ?? 1 Mbit RAM Videotext Page Memory
PCF8200 Philips Voice Synthesizer (get datasheet  from Scott) Providing the Speech
CAT 28C64BN CSI 64 kbit EEPROM Settings like TV Channels, ...
HM27C1024 ?? 1 MBit Eprom Speech memory or Boot ROM

MPU board

Navi unit with removed MPU board and removed protection shields


When I browsed the Internet for all of these components, I was frequently led to some UNIX/LINUX pages. So it seems to me that the rumors are right when they say the Navi Unit is a downgraded UNIX microprocessor. Now the challenge will be to make an own boot CD for this system ...

Obtaining secrets from the Check Control (E38)

The Check Control in the instrument cluster of the current BMW 5/7series hides somes secrets. Here is the procedure how to unveil them and how to unlock the system to get access to all tests:

  • Turn ignition to pos. II
  • Push right button in the instrument cluster and keep it pushed. You will first see "Check Control OK", some seconds later you will see "Test Nr.01"
  • Push the left button on the instrument cluster to see the car's identification number. Add the 5 digits together and write down that number, you will need it for unlocking all the functions. Example: DG23278 will lead to 2+3+2+7+8 = 22
  • Push the right button until you see "Test Nr.19"
  • Push left button until you see the number that is equal to the one you calculated above
  • Push right button again
  • Now you will have unrestricted access to Test No.3-21. If you made an error in the procedure mentioned above, Test No.3-21 will only display Lock:ON

    Most of the tests are self-explaintory, and here is a first listing (as far as I can recall):

     1. Display Car's identification number, HW/SW version, date of construction
     2. A very beautiful instrument test
     2. Current consumption (liters/100 km)
     3. Current consumption (liters/hour)
     4. Average consumption (liters/100 km)
     5.Current range
     6. N/A
     7. Average fuel in tank (liters)
     8. Current Speed (kph)
     9. System voltage at Term. "R" (Battery Voltage)
     10.Country/Language (US, Spa, Ger, Jap, etc.)
     11. Units am/pm
     12. Average Speed
     13. ETA
     14. Date of Software Mask
     15. Production Diagnosis
     16. ""
     17. Display Vehicle Specific Data
     18. Alarm Changeover (cont. vs. intermittent OBC chime)
     19. Lock/Unlock
     20. Correction factor for fuel consumption (nicht ändern!)
     21. Reset all defect codes

     1. several numbers and data
     2. [Dispay Test]
     3. VBR: x,x (liters/hr)
     4. RW-VBR: x,x (liters/100 km)
     5. RW: x (km)
     6. N/A 7. TMTL: x,x (liters)
     8. V: x (kph)
     9. UB: xx,xx (V)
     10. LAND: 2=USA, 3=I, 4=E, 5=J, 6=F, 7=CDN, 8=AUS/GOLF, 0=D, 1=GB
     11. EINHEIT 1: B3, B4, B5, B6, B7, B8, B9, BA, BB, BC, BD, BE, BF, B0, B1
     EINHEIT 2: [similar to above, I didn't want to mess with it]
     12. VANK: xx,x (kph)
     13. ANK:xx:xx
     14. ROM:
     15. DIAG: 01 01 000 E3
     16. PORT: 01 101010000, 02 101010000, 03...etc
     17. PROM: 00 12, 01 37, 02 18, 03 E6, 04 02, 05 B3, 06 FF, 07 7E
     18. HORN: DTON or [DTON flashing]
     19. LOCK: ON
     20. KVBR: 1000
     21. RESET?

    Watch TV / Videotext during driving

    This works on all 5/7 Series with the Mk. I  Navigation System (the one with the male voice). On Mk II (the newer version with the female voice) you have to use "brightness" instead of contrast for TV and "color" instead of brightness for videotext to get the trick to work. I know that the trick works on latest 99 7series models as well. But I heard also that some cars sold into the US do not have any TV equipment on board. You will notice this as they do not have any TV option in the main menu. Also latest BMWs sold in Europe (2000 onward, 3/5/7 series) have the trick disabled! The only chance to get the TV running is somewhere hidden in the menu of the BMW Sevice Tester DIS. But up to now I can't thell you where. If I ever find it out, I'll post it here!

    As far as I know the software update for latest navigation CD Roms does not affect or disable this trick.

    To watch videotext use the same procesure as above, but chose"brightness" instead of "contrast" (thanks to my friend Herbert Posner, who discovered this secret).

    Service Mode Menu

    If you have a MK2 Nav System (female voice), you can bring up a Service Mode Menu as following:

    Radio Service Mode

    For pulling out a nice Service Menu out of the Radio, do the following:

    A "Service Menu" will appear. You will be informed about To get back from this menu, simply switch off the radio.

    DK specs (E32)

    As everybody might know, the DK units (Drosselklappen = Throttle flap/valve) including a stepper motor and some variable resistors tend to fail after some years. As new parts are very expensive (why doesn't BMW or Bosch provide a repair kit??), DIY's cantry to fix these parts (I did it with success). As a precious help, here are two pages from the original Bosch DK spec including electrical schematic and resistor values. I got the whole document, so if you need more info, email me.

    Disconnecting the battery

    Before trying to repair something electrical on the beloved BMW, make sure to disconnect the battery first. Since the battery is located under the rear passengers seat (and it´s a PITA to get access to it), here is an easier way how to disconnect it:

    There is a 4 inch plastic cap on the wall below the left rear passengers seat. Remove this cap. It will reveal a screw. Unscrew it. Remove the second, black plastic cap. Under it, you will find a connection for the battery (ground). Open the screw to disconnect the battery from the chassis.

    Replacing heater control valves

    Here is the clue...

    I had the leak problem on my earlier '83 528i. The heater control valve body had a slight crack - lost much water (1 liter each day). Next point could be defective rubber gaskets inside. By the time, they wear off because of the opening/closing of the valves. If they are defective, the water drains through them and comes out on 4 dedicated holes on each valve. Anyway, you cannot repair anything inside. No standard parts. But If you want to check it, here ist the how-to:

    1) Loacte the solenoid/valve system at the drivers side mounted on the firewall. In my car, it is covered with a black plastic cover.

    2) Remove the cover (pull upwards heavily, will be hold by the metal rings)

    3) Find the metal plate with 6 screws holding it

    4) open the screws

    5) remove the metal plate with the solenoids (pull out)

    6) check the rubber gaskets

    7) fill some water into the remaining body and you will see the water coming out through the 4 holes (overflow function).

    BTW: Spare part is about 160$ (+90$ labor).

    Front Shimmy

    Really hevy front shimmy can occur when front tires are worn uneven. Balancing does not help always. Happens at 60-70mph (90-100km/h). After replacing front tires, the problem is mostly gone. Worn bushing can also cause a shimmy problem. BMW replaced front bushings at my E32 with full success. All shimmy was gone!

    Wind noise from doors

    Wind noise from doors can occur above 120mph(180km/h). This happens due to leaky door seals. To solve the problem, open the door, move power window down, pull the upper part of the door towards you, so that it bends for 2-3cm (1 inch). Be careful not to brake the window frame. Do this gently three or four times. Close the door and testdrive. If the problem persists, do the same procedure again. It helps.

    ABS control module connections

    Here are the ABS control module connections (taken from BMW's ETM):
    Pin # Direction  Function Location
    1 I Battery ABS relais
    2 O Switched ground Magnet valve front left
    4 I Ground Wheel sensor
    6 I Wheel sensor front left -
    7 I Wheel sensor rear left -
    9 I Ground Wheel sensor rear left
    10 I Ground distribution -
    11 I Wheel sensor front right -
    14 I pump relais input -
    15 I battery power generator
    18 I switched ground magnet valve rear left
    19 I switched ground magnet valve rear right
    20 I Ground distribution -
    21 I ground wheel sensor front right
    24 I wheel sensor rear right -
    25 I brake light switch -
    26 I ground wheel sensor rear right
    27 O switched ground valve relais
    28 O switched ground pump relais
    29 O display ground check control display
    32 I display valve relais(?) valve relais
    34 I ground distribution -
    35 O switched ground magnet valve front right
    Note: I means input (to the control module), O means output (from the control module)

    Pins not mentioned are not used/not connected

    Wheel sensors < 1 ohm

    Valve relais 70..100 Ohm

    Motor relais 34..58 Ohm