Failing or usless LCD odometer - a fix!

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Sean602
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Location: Roslin -yes the one with the chapel in Dan Browns book.
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Failing or usless LCD odometer - a fix!

Post by Sean602 »

So i Joined this forum a while ago as i needed to find info on fixing the dash on my newly acquired Dispatch ( http://www.frenchcarforum.co.uk/forum/v ... =3&t=42996 ) Ive been busy with this problem for a bit.

I had taken the dash out to replace the bulb on the fuel gauge but in the process had missed a locating screw and in the wrestle the odometer reset pin must have disturbed the ribbon to the digital odometer,

I had tried to solder it back resulting in melted mess then bought £40 replacement dash only to find that the chip for the mileage is on board , my van had gained 100K miles and the dash stopped working after it got warm and dried out. Bugger

The main trouble is the module is attached via a polymer coated ribbon which is heated and pressed on to the board when the polymer is at a certain thickness it conducts when its thicker it resists, the difference between the two is the thickness of the copper trace on the board. Being able to replicate this using a soldering iron or a domestic laundry iron is at best hit or miss - believe me ive tried! Its also common for there to be water damage in this area whether its water form an open window going down the resit pin and selling on the PCB or if the polymer is hydrophilic there is often fuzz around the interface.

Finally worked out how to fix the problem and so here is the solution,

First of all the LCD doesn't emit light, it just goes clear where the cells make up the numerals. So first port of call is the backlight. This is the only lamp that is permanently lit so logically its the first to burn out- swap the bayonet bulb and holder for one of the other known working ones.
Image
check bulb by Sean602, on Flickr


still no joy? or some of the numerals not working ? stage 2

Dash out and split in to its pieces. 2 t20 screws or variations depending what its fitted to. You have to undo the yellow and blue multi pin connectors press the lock, flip the lever and they should pop off. You have to undo the 6 t10 screws and then undo the plastic clips - this allows the black front to pull off and then the clock faces can be eased off the circuit board - they are only held on by the pins to the various gauges.

now you will see the the black module held on by further clips , ease them off with a screw driver and post the led module into the gap below its housing
next split the white part 4 more clips and it hinges apart releasing the printed circuit with the led attached ( or not)
Image
detached ribbon by Sean602, on Flickr

you now have to clear any residue from the bonding process polish the copper traces with scotch bite or the like in the direction of the tracks. 3M the manufacturers of the ribbon state the correct process to clear the residue from the ribbon - a cotton bud soaked in acetone free brake cleaner worked wonders.
Image
DSC00496 by Sean602, on Flickr

you can do as i did and test it all now , plug the board in to the loom turn on ignition and with a finger hold the face of the ribbon on the board to see if you can get contact and cells going clear, as I discovered it just needs the slightest of pressure to make good contact.

Now you have to cut a piece of plastic (i tried old PCB and thicker plastic but found a piece of CD case perfect) cut it to the same size as the un printed part of the board. Cut away the bottom left corner to leave space for the reset pin. While holding this piece in place drill both the plate and the board 1.5mm outside of the outermost copper tracks ( the outer tracks are un used so dont worry about damage) I used a 1mm drill for the small self tapping screws i had left over from a maplins box then drilled the plastic to 1.5mm clearance hole .
Image
holes and plate by Sean602, on Flickr

You need an even and gentle pressure this wont happen if you just clamp down the plastic on the board. I used a small piece of sticky backed foam
Image
DSC00499 by Sean602, on Flickr
a bit rubber band cut and glued between the screws would probably work, then its back out to the vehicle , hook it all up place the ribbon under the clamp and fiddle about till you see all the cells working,hold the ribbon and tighten down the clip.
Image
screwed down by Sean602, on Flickr
back to the bench and re assemble the dash, take care plugging the clocks into the PCB you have toget all the long pins into their sockets and they are easily bent.Its best if the board is loose in the white housing till its all in. Re fit and - bobs yer uncle (then panick about the miles you have done and remind yourself to get a timing belt kit on order)

If its only a few cells that are not lighting then you could just make up the clamp and try clamping to see if it makes better contact - otherwise peel the ribbon and follow the above

if the ribbon is faulty at the glass end then sorry not worked that one out yet.

Image
DSC00502 by Sean602, on Flickr

Good luck hope it works

( Ok its not the most comprehensive step by step guide. Im not going to go in to huge detail - if you cant work how to get the dash out or the the LCD module out its little housing then its probably not for you - if your pretty handy at doing stuff then you'll get the principal. If you go tonto with the Black and Decker drilling 1/2" holes in your dash for 2"10 woodscrews don't come bleating that your dash wont work. Its a fiddly job with tiny screws and 0.5mm electrical tracks needing aligning while you do up the screws - still its saved me a few bob and hopefully others will find it usefull to know that they CAN be fixed)
kissing the lash
white van (turbo, computer and built by Citroen, what could possibly go wrong!)
orange 2cv
blue 2cv( been to the Sahara and back)
red Dyane( in bits)
Skoda (thank goodness there is a teutonic vehicle on the drive)
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Si_Woods
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Joined: 20 Dec 2021, 10:51
Location: Limerick, Ireland
My Cars: 2003 Peugeot 307SW 1.6l P
2008 Citroen C4 Grand Picasso 1.6l TD
2002 Peugeot Expert 1.9l D
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Re: Failing or usless LCD odometer - a fix!

Post by Si_Woods »

I have had this exact same issue with my odometer LCD, it stopped illuminating back in October(2021), on my 2002 Peugeot Expert van (1.9D).
Thank you for sharing your pictures and steps taken to fix this issue, I didn't find much else about this issue online. This has greatly helped me to fix mine.

At first when I saw the LCD ribbon had come off the board and before I found your post, I thought I'd have to replace the instrument cluster. So I headed online and had a look for one, surprisingly there wasn't many for the years I needed and the cheapest I found on eBay was £200 plus shipping :shock: sod that, plus the recorded mileage is recorded on the circuit board so replacing it would show mileage from another vehicle.

In my case I didn't have a suitable solvent to hand to clean the copper strips, so I carefully, under a magnifying desk lamp, cleaned off the glue using the tip of a carpet blade.
I made a clamp just like you did and using a piece of inner tube rubber with a piece of packaging foam which I glued to the rubber and when dry placed it under the clamp and tightened down the screws to the circuit board. This worked perfectly for me. I also trimmed the edge of the clamp to leave room for the reset pin, not shown in my image.

I went through all the dash bulbs to see what was working and what was blown and I had seven blown bulbs which I have now replaced and the display is like a brand new twenty year old display.
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2002 Peugeot Expert LCD Odometer ribbon fix to circuit board
2002 Peugeot Expert LCD Odometer ribbon fix to circuit board
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