The Return of the Pixels: The third installment in the e36 instrument cluster LCD repair trilogy

A 10-minute shorter version of this video can be found here (honestly, it is even better):
• The Return of the Pixe...
Please make sure you see this additional video (before you begin working on your cluster):
• Instrument cluster LCD...
Electrical issues are amongst the hardest to diagnose and repair - most certainly when intermittent. It took 4 tries for me to finally repair the intermittently fading pixels of my e36 LCD odometer screen.
Summary:
1. There are multiple contacts that trigger LCD pixels to be in on (open) and off (closed) state
2. Two main points of failure could be at the rubber zebra (elastomeric) connector and/or the cold solder/partially corroded soldering of the pins of the LCD housing on the PCB board
3. It ended up being both in my case
4. Procedure:
- remove two bolts (T15) atop of the cluster
- loosen air bag bolts found behind steering wheel (T27) (if your e36 is not an M3 you may get away with removing the cluster without the need to remove the steering wheel).
- Remove the key from the ignition completely (to avoid airbag warning light - or if preferred disconnect the battery)
- pull away the air bag system and carefully remove the two wires
- unscrew the 16 mm (~5/8") bolt holding the steering wheel
- mark precise location so you do not misalign steering wheel when placing it back on
- pull steering wheel off and wiggle the cluster out and turn slightly to release the 3 harnesses
- place back steering wheel (without bolting it) so it is not hanging loose
- remove cluster and unscrew the 5 torx bolts (T10)
- open carefully and determine if you screen rubber connector needs cleaning (after removing the metal clip that holds it)
- if the soldering on the PCB needs repair, then you need to drill the tops of the 10 pegs holding the PCB to the back of the cluster.
- resolder the pins that appear corroded. Mine was 2nd row 2nd from the left
- I would have re-soldered all 38 or 45 pins, but I have the protective coating
- It is possible if your car is not an M3 or an older e36 that your pins may not have a protective coating (other videos showed exposed pins).
ACKNOWLEDGEMENTS:
Special thanks to all who guided me and commented on my earlier videos and replied to my questions on their videos. This includes the following people/channels in the order of help received or video reviewed:
- 23tlujan23
- Geoffrey McEvoy
- Pixelfehler Hamburg
- Francesco ’s BMW Kanal
- Fischers Garage
Disclaimer: This video is for educational purposes only and I hereby release myself from ANY liability for any damages you may incur by attempting any of these procedures. If you are not comfortable working on your car, please seek professional help. This clearly requires specific tools and comfort with soldering. Improper procedures could lead to injury and/or potential issues with your airbag system.

[@nesnas]

I had to open it up again today since the problem returned. I don't have another video, but when plugged, pushing on pins #7,8, and 9 (top row inward - right side when facing the LCD screen), as well as the left most pins bottom row resulted in intermittent pixel flickering. Since it is very difficult to etch at the protective coating without invariably damaging the PCB board component, I took the conservative route of touching the top of each of the 45 pins with a 280 °C soldering iron for 5 seconds. I can see the original solder melt under the protective coating (viewing under the magnifying glass), and for now, that removed the intermittent issue; and after I was done, when I was pushing against the pins in the back, there was no more flickering! I think, the 5th time opening this is the charm - fingers crossed. Having built up this experience with this job, I can get to these pins after 15 minutes; hence I was encouraged to open it up again!

[@nesnas]

5th time was not the charm; the sixth time was. Here is the last video that finally fixed instrument cluster (addendum video):
ua-cam.com/video/VIeLri_AI7M/v-deo.html

[@danc2014]

I think the repetitive use of the odometer reset button allowed reg board to flex and solder joint to crack. Luckily it is not a broken traces but a solder reflow.

[@nesnas]

Thanks. I agree. That's how I first noticed the issue since when I used to press the reset button and the pixels would flicker in and out. But honestly the factory soldering job was in my humble opinion sloppy - likely a semi automated process with minimal flux/solder. I was generous with flux/solder and made sure I don't have to do the job again (I followed this up with another video after this in which I soldered all 45 pins). It has been perfect since (fingers crossed)!

[@leecruz2952]

Awesome video bro. Very detailed instruction. Now it’s time for me to fix mine.

[@31acruz]

Thanks for making this video, very informative.

[@GaryVolts]

Hi Nasri. You should get some kind of award for inhuman persistence. The problem looks to me like its the zebra strip. That thing is flexible and the design depended on that property to bridge the signals from the gold contacts to the LCD planted contacts. When it gets old it looses its sponginess and takes the shape its been held in instead of pushing back on the LCD and contacts. May even shrink in volume, you can see how some of the wrong LCD segments are being activated because the zebra is bridging the wrong connections, diagonally. If it was available, the right repair would be to put in a new rubber zebra strip I would think.
The soldered part of the assembly should be solid, but pushing on the PCB near it is moving the zerba connector ever so slightly on the other side. BTW, those rubber strips are also called elastomeric connectors.
BTW, are the lights inside the LCD chamber replaceable without disassembling the cluster unit as you have done?

[@nesnas]

Thank you Gary for your comments. To answer your last question regarding the replacement of the light bulbs within the LCD chamber: Yes. They are super easy to twist off and replace without having to open the cluster. You only need to remove the cluster from the dash.
On your discussion of the elastomeric connectors: I also considered this to be the culprit and someone else on one of my videos shared the concept of the rubber potentially slightly shrinking with age/heat (22 years now). Although quite likely to be the case with other clusters, in my case, what finally fixed this issue is the complete soldering of the 45 pins in the back (specifically pin #7 and the few around it); please see also this final video:
ua-cam.com/video/VIeLri_AI7M/v-deo.html

[@sheepdogtactical1430]

Put Diolectric grease in the connector and send it 😎👍