I checked fuses, but they were all ok. It wasn’t long till I determined it was a cluster failure. Luckily, I had the Mercedes cluster removal tools, which I purchased many years ago at Mercedessource, to remove cluster from my W126. Even though C209 is not listed, they work perfectly.

Using the cluster removal tools, I had the cluster out within a few minutes.

The next challenge was to find someone to fix the cluster, within a short space of time. I initially contacted “Ringwood Speedometer Service” and “Automotive Instrument Repairs”, but both business owners were on leave for at least another week. Back to the drawing board, I trawled the web and found Justin at “Australian ECU Repairs”. Justin provided a fixed price for cluster repairs, ranging from $385-$440, depending on the chassis type. As ours was a C209, price was $440, not including shipping.

I sent the cluster via Express Post on the Wednesday and received it on the following Wednesday via TNT Express.

As soon as it was plugged in, cluster lit up and when turning key I had full instrumentation.

After this experience I can highly recommend Justin at “Australian ECU Repairs”. Their website is excellent, allowing online bookings and then providing fast turnaround. I would not hesitate to use Justin now for any ECU or cluster work, even though I’m located in Melbourne.

Author:  Nick Gruzevskis is a contributor to classicjalopy.com, and the custodian of a great collection of classic and modern cars.  Links to some his other articles can be found here

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I don’t really like not being able to trust my gauges to be generally correct, so I wanted to see what I could do about this.   The issue seems to be mostly due to grounding.  The whole cluster gets ground from one plug, which then provides ground to each of the instruments, and lights.

A friend of mine with a W123 had fixed a cracked solder joint in his cluster that had made a big difference.  I’m terrible at soldering, so he offered to take a look at my cluster and see if the same solder joint needed repair.

Last week I removed my instrument cluster.  On removal, it had obviously been out before.  Somebody had written an odometer reading on the back, which I assume was done when the odometer was previously repaired.   The cluster was generally in very good shape, except somebody had tried to pull it out from the front before and slightly damaged the front cover, so I had to be careful.

I find the easiest way to remove these clusters is to remove the drivers side speaker and push it out from behind.  The W123 instrument cluster is harder than the W126 version, because the oil pressure sender is mechanical.  For reasons only known to them, Mercedes-Benz give you almost no slack to play with on the oil pressure line and speedo cable.  Even an extra two to three centimeters would make a big difference.

A 10mm spanner is needed for the oil pressure line, but the rest of the connections can be done by hand.

My friend looked at my cluster, and didn’t see the same solder joint broken.  There was some oil inside the cluster, and some of the screws were a bit loose.  Since the oil pressure gauge does not seem to be leaking now, I wonder if it leaked in the past?   Regardless he gave it a clean and also made sure it was screwed in properly.  From what I understand, the screws are important for the grounds.

I also decided to add another ground line.   From reading on the forums, it seems a lot of other W123 owners do this.   I figured it couldn’t hurt.  I grabbed a couple of ground lines with eye terminal from the 420SEL parts car. One terminal went on the other side of the ground bolt behind the W123 instrument cluster, held it on with a washer and nut, also from the 420SEL.  I put the other ring terminal behind one of the screws on the instrument cluster.   The only non Mercedes part was a connector between the two ground lines.

I put it all back together and took the car for a test drive. Getting the oil pressure line on is quite fiddly.  Eventually I got the cluster back in place and tested all the connections.

Today is very hot, mid 30s, so I was curious to see how the temperature gauge performed.   The fuel tank is full, so I will not be able to test that until I have used some fuel.   At least on the 20 minute test drive I did, the gauge seemed to perform very well.  It crept up to about 100 at one point in stop and go traffic, and then when I was on the move again, slowly came down.   It never used to perform so predictably.   I will keep an eye on it, but so far it seems like a big improvement.

The post W123 Instrument cluster grounding appeared first on Classic Jalopy.

The first step is to remove the cluster and have a look.  You can’t order the gears until you check what you have, as the various combinations of instrument cluster use gears with different numbers of teeth.   The factory tool to remove the cluster is not necessary.   The easiest way to get the cluster out is to remove the speaker and push it out from behind.

Once removed, the instrument cluster can be unplugged (there are a lot of plugs) and brought to a workbench.  The first thing that must be removed is the exterior temperature display.   It is held onto the bottom of the instrument cluster with two screws and simply slides out.   These two screws also hold in the speedometer.

Next, there are four more screws to remove the speedometer housing.    They are the gold ones with the hexagonal heads on the edges.

Once those screws are removed, the entire assembly for the speedometer just lifts out, once the warning light that clips on is removed.    At the same time, the two smaller inner bulbs for the indicators, and larger outer bulbs for the illumination should be removed.

It is not possible to repair the odometer while the speedometer is still in its plastic housing.   The four inner screws must also be removed.   On my cluster they were the silver phillips head screws, but I’ve also seen gold flathead screws on other clusters.

The speedometer unit lifts out, and care should be taken to not lose the four rubber spacers that go on the plastic feet that stick through the circuit board.   There are also plastic baffles for the light bulbs that slide out.

With the cluster removed, you can see the original vivid orange the speedometer needle was, as well as the the max speed markings and 50/60 hatching.  These should all match, so I elected not to repaint my speedometer needles, as I do not have a steady enough hand to repaint the sections on the speedometer face.   They look terrible when they don’t match, as well as looking terrible when painted red, not the factory orange.

The odometer gears are accessed to the right of the speedo.   There is a cover held on by two tiny philips head screws.   In the picture above, the cover has already been removed (top right) and the tiny screws are on the table.  The cover is a bit of a pain to get off, due to the black box.

With the cover off, it is easy to see the three gears that wear.   The small one, from the drive motor on the right, the top one, and the next one.  There are also two more gears that don’t seem to wear and do not need to be replaced.

The main thing to do here is to remove the two larger gears and count the teeth on the inner gear for each.  The outer teeth seem to always be 48, but the inner teeth vary.   I guess I’m going to need reading glasses soon, as I couldn’t count the inner teeth without the magnifying glass app on my phone.   When I last did this a few years ago, I didn’t need any assistance!

The picture below shows one of my gears, including the missing teeth.

The smaller gear always seems to have 12 teeth, so does not need to be counted.   There also seems to always be a 12/48 gear.   However, for my 560SEL with a 260KM/h speedometer and a 2.47 rear end, I needed a 14/48 gear.   My old 300SE needed a 13/48 and my 560SEC with an MPH speedometer needed an 18/48.   I purchased my gears from Garagistic.

By the time the gears arrived, plus I had a bit of work travel, it had been a few months since I removed the cluster.   It is a pretty simple matter to remove the two larger gears, but the original small gear is on a brass bushing, which is no longer needed.  The easiest way to remove it is to break it with a set of cutting pliers.

Once that is off, the new small gear is just press fit on.  The two larger gears are much easier to put in.   At this point, I made a mistake.  I assumed that the white gear was the replacement for the light coloured gear, and the blue gear was a replacement for the black one.   I put everything together and tested in the car.   It didn’t work properly.   I then removed it all again, and looking at the photos of when I did my 300SE, I realized I had them backwards, and it was binding.   The blue one should have been the top one.

I also used a small amount of rubber grease, as I found I could hear the gears on my 300SE with no lubrication.   As can be seen from one of the pictures up above, the original gears were lightly lubricated.

At this point, I also thought I would try replacing my broken clock with a different one.  I have a few spare W126 instrument clusters, so I removed the clock/tacho from the one that was in the best visual condition and swapped it over.

This was a pretty simple thing to do, but proved futile, as the replacement clock didn’t work either.   I put my old one back, as it was in much better visual condition than the other two spares.   Removing and the bulbs for the illumination a couple of times caused them to fail, so I ended up replacing both of them.  I keep bulbs like this on hand so it was easy to do.

In doing this testing, I didn’t push the cluster back in properly which made it easy to take it in and out until I was happy with everything. Once I was, I pushed the cluster back in place and replaced the speaker.

The final test was to check the accuracy of the odometer with my GPS.  On a 2.8km course, the trip odometer recorded 2.8km, so I was happy with the result.    I’m glad my 560SEL odometer repair is finally done, as I don’t like to drive cars without a working odometer.

The post 560SEL Odometer repair appeared first on Classic Jalopy.

I ended up installing it as part of my failed attempt to change the centre vent.   Even after changing the bulb, the vent illumination was not working.   I realized that it must require the instrument cluster to be plugged in.    This proved to be the case, and also fixed the illumination for the outside temperature gauge.

Before I re-installed the cluster, I added more ATF to the speedometer cable.   This is an attempt to lubricate it and stop the speedometer needle bouncing around at low speed.   I then plugged in all the electrical connections.   Most of them had plenty of slack, so this part of the job was quite easy.    Re-attaching the speedometer cable is more fiddly as there is minimal slack.

I didn’t push the cluster all the way in and did a test drive around the industrial complex.   It was soon apparent that the bulb that illuminates the left hand side had blown.   I had one left in my box of bulbs, so I quickly swapped it over.    If you own these cars, its really handy to keep spares like this on hand.    On the less positive side, I can’t say that the ATF has really helped my speedometer needle a great deal.  It is improved, but not by very much.  It was worth a try.

Given that you are sitting in front of the instrument cluster the whole time you are driving the car, I think is a very worthwhile improvement.  I find these sort of projects really make a big difference.  My refurbished W124 instrument cluster wasn’t all that expensive and only a few hours work.     It is especially apparent when compared to how it was.

The post Refurbishing a W124 instrument cluster – Part 4: Installation and testing appeared first on Classic Jalopy.

While I was in the UK for work in January, I purchased a good used W124 instrument cluster housing.   My plan was to transfer my instruments and electronics to that new housing.   The actual gauge faces were in good condition.    It’s been on my to do list ever since then.  I didn’t know about the bitumen stuff that covered my cluster back then, but this has the added benefit of fixing that too.

The new housing is almost perfect.   It has no white spotting, and the glass is in great shape.  It still has the rubber blocks that help the cluster stay in too.   The only slight imperfection is there is a little bit of melting around where the dash lights go.   A previous owner of this cluster probably used the wrong bulbs.   It is also ever so slightly different, with a ridge at the bottom.

I had already removed the cluster and the outside temperature display which is the first step.    Unlike on the W126, where its easier to remove the instruments individually, I found on the W124, it sort of all has to be done together.   I first removed all the screws that hold in the speedometer and rheostat.  However, this didn’t really want to come out until I removed the screws that hold in the left and right circuit board and instruments.  There are two on each side.  For example the little circuit board on the top left is underneath the silver housing for the clock and tacho.

A lot of people at this point would paint the needles on their instruments.   I personally don’t like to do this, as the needles should be the same colour as the max RPM marks and crosshatched section on the speedo face.   My hand is not steady enough to repaint those, and freshly painted needles just show up those sections unless they are done too.

Getting the instruments in the housing was not hard, just a bit fiddly.   I found I had to start by clicking in the small circuit board above the clock/tacho and then slowly guiding in the other instruments.

The other thing I had to change was the backing for the warning lights.   This cluster had obviously come out of an Airbag car.   Its a simple matter of using tweezers to pull out the backing strip and put in the correct one for my car.   These backing strips vary quite a lot, depending on the car they came out of.  Interesting that the font changed a bit.

Just a simple thing like changing the W124 instrument cluster housing has made a huge difference.   As it sits in front of you as you drive the car, I think it’s a worthwhile improvement.   The white spot is gone, the glass is clear and I can see my instruments properly.   When I couple this with the repaired outside temperature LCD, its going to be a big improvement.

The final step for this process is going to be reinstalling and testing the instrument cluster to make sure I have it all back together properly.

The post Refurbishing a W124 instrument cluster – Part 3: Changing the housing appeared first on Classic Jalopy.

The main problem with these displays is that when exposed to too much hot sun, the LCD panel ‘bleeds’.   Over time, this makes it increasingly illegible, not to be mention ugly.    I previously fixed the displays in both my old 300SE and the 560SEC.    The W124 outside temperature display is basically the same as the unit found in the W126 and W124.  They are just in different housings.

The good news is that replacement LCD panels are available.    The LCDs used changed in about 1988, so for the 300TE I needed to use the newer version of the LCD panel.    I also bought another earlier one to fix a spare W126 unit I have on hand.

The W124 outside temperature display unit just screws into the back of the instrument cluster.   Its the first thing you have to remove to get the gauges out, so now was a good time to repair it.

To repair the W124 unit, there are four small screws that must be removed.   On this model, the upper and lower parts of the housing must come apart to get to the front part where the LCD panel is.

The later unit as on my 300TE has a more sophisticated baffle for the bulb that illuminates the display.   Otherwise there are basically the same, with the two black ‘blocks’ that transmit the signal from the PCB to the LCD panel.     The dot at the top of the LCD panel faces upwards.

As I purchased two LCD panels, a new one and an old one, I had the issue of not being able to work out which was which.   Probably it would be evident with a strong magnifying glass, but I couldn’t tell.   I tried one, and as it turned out, it was the wrong one.    The W124 outside temperature display is a separate unit to the instrument cluster, so its possible to test it without installing the entire instrument cluster.

It also looks like the blub in my unit has blown.  It would be easy to change if you are good at soldering.   This is soldered onto the PCB, and I’m terrible at soldering.   For now, I’m going to leave it as is.    I’m still pretty happy with this repair.

The post Refurbishing a W124 instrument cluster – Part 2: W124 outside temperature display appeared first on Classic Jalopy.

1. It had the dreaded ‘white spot’ disease.   Not just on the instrument cluster surround, but the inside of the glass too.
2. The outside temperature LCD was all cloudy and difficult to read.
3. The speedometer needle jumped around at low speed.

I assume the white spot is some kind of mould.  it seems to affect cars that have spent time in the tropics or humid environments the most – e.g. Hong Kong, Singapore, Queensland etc.   My car spent over 10 years in Queensland, so I guess that’s where it came from.

The other night I started replacing the front speakers in the car.   I will cover this separately, but this made it very easy to push out the instrument cluster from behind.     On doing this I noticed a fourth thing.   A previous mechanic or owner had used some kind of thick black bitumen like substance to hold the cluster in place.   It was really sticky and hard to get it off the dash surround.     I tried to get as much off the inside of the dash as I could.   It was also hard to get it off my hands.

I cleaned it off as best as I could and unplugged the cluster.    I put the cluster aside to take home.  My first task was to lubricate the speedo cable.   This should improve the jumpiness of the needle at low speed.   I used ATF in a syringe.  I wasn’t able to get very much in there, but I will have another go before I put the cluster back in.    The roll of tape was to keep the angle of the speedo cable up.

I really don’t know why the W124 uses a cable.   The earlier W126 is all electronic.  On the W124 they still have to convert it to an electronic signal for various accessories like the tempomat and the speed sensitive volume feature on some radios.    Seems kind of a step backwards.

The next phase of my W124 instrument cluster project will be to refurbish the outside temperature display.

The post Refurbishing a W124 instrument cluster – Part 1: Lubricating the speedo cable appeared first on Classic Jalopy.

The easiest course of action would have been to solder a wire in place.   I didn’t go with that approach as there is no soldering used on this circuit board at all.  It uses rivet looking connectors to take the power to the other side.    I wasn’t sure how well the backing would hold up to the heat and was worried about the solder breaking off.  The board flexes each time the power connectors are removed or installed and it can get hot in behind the dash.

The copper tracks on the board are particularly wide.   This gave me enough room to drill small holes in strategic spots.  I chose spots that were wide enough so I did not touch any other tracks.   I then used conductive screws to bring the power to the back of the board where I could use wires to get past the crack.    The bolts are 3mm.

The four screws are set up so I can bypass the break.  The break is near the square hole in the top left of the picture.   The outer track is for ground and the inner for +12v.   The screws stick up a bit more than the rivets do, but they are quite secure and are not going to come off over time.    You don’t want normal screws at the hardware store as most of them are coated and have low conductivity.

The picture above also shows my quite rare temperature gauge.  This was generally fitted to cars in very cold climates only.  It is very useful in hot ones too!

Once the screws were in place I was able to create two lengths of wire and crimp eyelet connectors on each. This is a similar approach to the tachometer.  The tachometer uses the rivets instead of the screws though.    It was then a simple matter of connecting up the wires around the back of the speedometer.  The wires are tucked so they should not be in the way.   The only downside is the board sits up a bit  more on this corner.  The bulb just near the wires leaks a little light because it is sitting up.

Once I put the cluster back in I was rewarded with lights that worked without flickering or pushing on the cluster.

While I was at it, I also swapped over the petrol gauge from the parts cluster.  It was in much better shape than the one on the car.    I have not yet taken the car for a test drive, as the weather in Sydney has been poor.  I expect my home Citroen DS instrument cluster repair to hold up well.

The post Citroen DS Instrument cluster repair appeared first on Classic Jalopy.

My first assumption was the rheostat had failed.   The rheostat is the dimmer that lets the driver control the brightness of the instrument cluster lights.   Over time, these can develop dirty connections.    On the DS, the rheostat is actually not part of the cluster, but under the steering wheel.   This made it easy to test.   Once I had removed the instrument cluster I could use a multi-meter to check that I was getting 12v to the pin for instrument lighting.    I was.

Next step was to check the cluster itself.   It is simple to remove on the DS – four screws, three electrical connectors and the speedo cable.   Another four screws opens up the cluster.

At first glance, there did not appear to be anything wrong with it.   I didn’t think it would be a blown bulb because there are two of them and both were working before it failed.   In any case both bulbs looked good.

Readers who are familiar with the DS will immediately spot that my instrument cluster is not correct for a 1970 model car.     It is either a 1973 model or has been pieced together from multiple models years.    How do I know?   For 1970 and 1971 the instrument clusters had long needles for the speedometer and tachometer, and the braking distance was a ring set above the speedometer needle.    Specific to 1970 models was markings on the speedometer for the shift points.    In 1973 the clusters went to long needles and some time in 1973 the indicator lights flash together on the dash rather than separately.

When I purchased the car it had this cluster with a different MPH speedometer with a short needle.   Later, I changed the speedometer for a KM/H unit and the front cover for a nicer one.   I don’t know if the entire cluster or just the speedometer was changed in the past.   I keep an eye out for the right 1970 cluster with shift points for a DS21 but so far I have only ever seen the D Special/D Super unit.

After doing more testing I found that the cluster could light up, but it was extremely sensitive.   It would stay lit up if the cluster was dismantled and not in the dash properly, but if i bumped it or re-assembled it the lights would no longer work.

I also noticed that one of the bulb holders was cracked so I changed that one.   That change seemed to make it a bit less sensitive, but now knowing the root cause I’m not sure that was actually the case.  I would get it back in the car and it would work until pushed back into the dash properly.

At this point I was really stumped.   I got out my spare parts instrument cluster and dismantled it to see if I could spot any differences.     Perhaps there was a bad connection in the cluster somewhere?  I removed the circut board on the parts cluster which is the simplest circuit board I have ever seen.   There are almost no electrical components, just copper channels to direct power to the various bulbs.    The board is so simple I couldn’t see how a bad connection would even occur.

I went back to the good instrument cluster and removed the circuit board to compare.   This immediately showed up the problem.   There is a crack in the board!  The place it is cracked has two functions only – power and ground for the cluster lights.   The crack was not noticeable until the board was removed which was why it was so intermittent and why the cluster was not working pushed back in the dash with more pressure against it.

Now I know the problem it should be a fairly simple repair.   The board is so simple even that thick section has only two tracks.     I’m not sure if the crack has been there a while and it just got worse removing the cluster for the fan light, or if it somehow cracked during that modification.

The post Citroen DS Instrument Cluster Lighting appeared first on Classic Jalopy.

The antenna was looking very shabby also, and it took a lot of searching to find a replacement that looked period and didn’t have lots of plastic parts.   After a lot of searching I found one in the UK at a place called Classic Car Stereo, which with shipping wasn’t cheap but I didn’t like any of the other options.

The Retrosound Model 2 also provides a bluetooth handsfree option.   I mounted the microphone on the rail under the roof.  It seems to work quite well although so far I have only made calls from the garage!

With the speakers and microphone mounted, I was able to re-install the seats and other trim options.   I bought a rear deck cover to replace the old carpet which is starting to make the car look less tatty.

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