- Phillips screwdriver.
- Soldering iron.
- New capacitors and new bulbs.
1. Disconnect the battery!
2. If they your steering wheel extend, you should be able
to get the dash module out without having to remove the steering
wheel. Extend it all the way out, and then you should be able
to slide it out of the same side as the turn indicator, takes
a little wiggle, but it works perfectly.
3. Else, you will have to remove the steering wheel, be extremely
careful if your car is equipped with airbags (see Bentley
manual). You can remove the the plastic cover under the steering
wheel and access the 2 bolts that hold the steering column
up. Remove those bolts and the column will drop enough for
you to access the instrument cluster, you can set off the
airbag with this method!
4. Remove the instrument cluster and open it.
5. Click in the picture,
the yellow arrows are the capacitor which go bad, the red
arrows are the screws which must be removed and the blue arrows
are the retaining clips which must be carefully pried back.
Once that is done you can remove the glue on the edges of
the board and remove the board.
6. Check the values printed on the side of each capacitors
(like 220mF 40V). It has been suggested to replace them with
105°C capacitor but 85°C will work fine.
7. But sure to take note where each capacitor is located.
Check polarity when removing and installing the capacitors
or you will damage your board. Capacitors are always marked
as far as negative and positive.
8. Use a desoldering tool to remove the old capacitors and
solder the new ones without touching other connections on
the board.
9. You should change all the light bulbs while you have the
cluster open!
10. Recoat the bottom of the board with an insulating varnish
for the circuit board and reassemble.
Some capacitors don't have a value printed on them: EPJ 22-40
W5 = 22 microfarad and 40 volt. (Can be replaced with 50V
ones.)
Bulbs part # from Stewart Ebrat:
- 12V3W (07.11.9.978.372) Quantity: 3
- 12V1.5W (62.11.1.391.260) Quantity: 6
- 12V1.2W (62.13.1.383.311) Quantity: 10 (Note same for OBC)
- OBC Light is #62 13 1 383 311 quantity: 3
- Heat and fan panel light: p/n 62 11 1 391 777 Quantity:
1
A thought on Instrument clusters.
There is two model of instrument clusters, one from built
date: '88- Feb 89 with the coding plug in the wiring harness
(brown connector), and another one after '90, the coding plug
is inside the instrument cluster.
Both clusters boards are different inside and the bulbs are
also different. The new instrument cluster can be used in
place of the older one, but the older one won't work with
the newer BMW E34 because there will be no coding plugs. The
connectors are at different locations on the newer cluster,
but this doesn't affect the functioning.
Coding Plugs (from Bill R.)
It controls the odometer reading, miles/kilometer/ some of
the gauge functions as well. When replacing it you need all
the numbers that appear when you do the self test on the instrument
cluster. That will tell the dealer which version hardware/sofware
you have. You also must disconnect all connectors on the back
of the dash cluster with the battery disconnected and wait
a few minutes for all residual power to drain to keep from
damaging the memory on the coding plug. THIS is a must. Also
since the obc shares data with the coding plug, the plug to
the obc on the back of it must be disconnected and wait at
least one minute after the coding plug has been changed.
This will reset the obc for the new coding plug.
To switch from km to miles, you need to change the coding
plug.
|
|
Coding plug |
|
Images courtesy of Hannu Myllynpää
|
The problem with the coding plug is that it counts only up
to 300,000km or miles... After that your odometer stops counting,
we are still working on a solution:
I have friend that lives in Belgium and he used to work in
a shop that reparied BMW dash boards. English is his 4th language,
but he is a smart guy. He also states the instrument calibration
is in the module which confirms my observation. Bill
Yep that is the odometer module. it contains a 93C46 chip
made by national semiconductor and uses a communication port
called microwire.it has 64 words of memory (64 * 16 = 1024
KiloBIT). The odometer information is stored as 16 words in
what is caled a rolling-write memory. Formula to calculate
the data : Take mileage divide by 16 and also remember the
remainder. Take FFFF and substract the hexadecimal (mileage
/16). That is the data that needs to go into ALL of the 16
memory locations. Now look at the remainder you had from the
division : that is the amount of times you
need to write hex(mileage/16) -1 so for a mileage of 100 miles
:
100 / 16 = 6 with a remainder of 4
FFFF - hex(6 ) - FFF9
the memory dump becomes:
FFF9
FFF9
FFF9
FFF9
FFF9
FFF9
FFF9
FFF9
FFF9
FFF9
FFF9
FFF9
FFF9
FFF9
FFF9
FFF9
now modify the 4 first lines( 4 because fo the remainder
that was 4 ) to be FFFF- hex(6) -1 if youneeded 101 miles
then it would have been the first 5.
FFF8
FFF8
FFF8
FFF8
FFF9
FFF9
FFF9
FFF9
FFF9
FFF9
FFF9
FFF9
FFF9
FFF9
FFF9
FFF9
this gives you exactly 100 miles on the counter this rolling
scheme allows them to write precise information , and spread
the writes across the eeprom . it causes less wear and tear
on the module and makes the memory last longer. The module
also contains calibration data that pertains to maximum speed,
gauge calibrations and more. To calibrate that you need to
have access to what is commonly called the 'mother computer'
from BMW . That machine can update the data inside this module.
When a dashboard was so badly damaged it had to be replaced
we copied the information from one to another. problem was
that we couldn't touch the calibration data .So we only moved
the odometer data. There are other fields like oil change
counters and lifetime counter as well in that module. As well
as your cars chassis number and a couple of other things unique
to your car .It's basically your car's logbook and passport
roled into one..
Coding plugs and Fuel / Temperature Gauges: (Thank to
Bill)
After changing the capacitors, the the gas gauge and temp
gauge were still dead.
I changed the instrument cluster and I wanted to maintain
the odometer reading, so changed out the non volatile module
and it made the gas gauge and temp gauge quit. I put the new
one back in and it worked. So it seems that the coding plug
can get corrupted and affect the gauges also.
Capacitors don't solve it all: (Stewart Ebrat)
Have just solves 3 month long problem of no odometer, trip
meter, fuel gauge, service lights, economy gauge and message
board. Changed capacitors to no avail, searched Bruno’s
site as well as the forum's archive for any other answers
but was left disappointed. Only explanation was capacitors.
Finally took car to specialist Euro auto electrician who changed
the whole box below instrument cluster where globes and readout
lcd's are located. Luckily I did not change instrument cluster.
Total cost for labor and new box $450 AUD ($300 USD) and all
fixed. Box is actually second hand (stealer wants $1200 AUD
for new) but came with 24 mth warranty. Capacitors are not
the only cause of this problem. Hope this can help some other
board members avoid the frustration I experienced.
LCD, temperature gauge and fuel gauge out: (Grant Patullo)
Just letting you know I had the dash in my E34 535i fail
about 12 months ago and I replaced the caps as per the instructions
on your website and everything was fixed until 3 weeks ago
when the LCD readout and the fuel and temp gauges stopped
working, so I pulled the dash out again and replaced the small
tantalum cap on the LCD and also cleaned up few suspect solder
joints and reinstalled the dash. Whatever I did fixed the
fault and the dash is working once again.
Thanks for the great website and keep up the good work.
Thanks to George D, James Hartline
& Bill Rikard
|
