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Instrument Cluster Problem

19K views 50 replies 3 participants last post by  Daniel Viorel Dumitrascu 
#1 ·
my cluster looses power for a few seconds and then comes back on while driving. most of the time in the morning when the car is cold from being in the garage and not in the sun. At the same time when the cluster resets the LCD on the Comand turns off and then back on briefly but the music doesnt stop. Sometimes the LCD's on the cluster goes blank and the back light is stuck on even after locking the car for few hours. There was one small fault that says Possible steering angle sensor fault and my turn signal switch only blinks 3 times but doesn't stay on on both sides. The cluster issue sometimes happens a few times on every trip and sometimes i go through a few days without any issue. Sometimes when i start the car cold in the morning all the warning lights flicker a few times until everything settles down. I really thing its not a defective cluster since the Comand display loses power briefly but am not sure it happens every time since i don't always pay attention to the nav display.
My impression is that it could be a lose wire or connection somewhere. i would really like to try everything before i go on and get a new cluster installed since they are extremely expensive. What is weird is that sometimes the display on the cluster gets stuck to whatever says on it and the steering wheel buttons can not change it to different menu.
Any idea o what i should be checking first.
 
#2 ·
It almost sounds like something is going on with the CAN bus. Has your car been flooded or otherwise exposed to water in the cabin? There is a CAN bus connector under the driver's side door sill. Corrosion there can cause problems.
 
#3 ·
I don't think it was flooded. I will check that connector. Do you have more detail on how i can get to it? Also about a month ago the SRS light came on and went to a shop last week and they erased the code and said there is also a possible steering angle sensor fault that their scanner was reading. Anyway a week later and the SRS light came on. I also have a short on the Horn Fuse i belive #43 , the one with 3 feet witch makes me think the Steering Clock Spring is defective, Could that also cause the turn signal switch to not stick to the on position?
 
#17 ·
Just removed the cluster (easiest cluster to remove ever) and disconnected the harness and cleaned it with a little air pressure since it was dusty. My issue is that the cluster resets and sometimes the display gets stuck even when the car not started and key in only in position 1. Sometimes even gets stuck when checking the voltage on the screen and doesnt go anywhere uness i reset it by pulling the fuse. Last time i fully charged the battery it didnt have the problem for like 2 days so i just put the charger on it and the display reset as i opened the door right after it turned on. Seems like a issue with the cluster but then why does my command display and climate control display turn off for split second when the cluster resets.
 
#5 ·
This installation manual fro the SmartTop will get you to the CAN bus connector:

mods4cars product manual

The clock spring does not affect the turn signal. However, a bad clock spring can cause SRS problems as well as steering angle problems. But this is likely unrelated to your other electrical gremlins.
 
#6 ·
great help. That link just answered few of my other wonders about this car. :) Last time when they cleared the SRS code they checked and the steering angle sensor was the only code. Before the SRS code came on i got in the car turned it on and the cluster lost power briefly and then came back on with the SRS light on. The same thing happened last time when the SRS light came on. Can the clock sprig affect the SRS and the Cluster? I am not going to rule out corrosion because a while ago top and left brake lights stopped working and all i had to do is clean the connection between the bulb for the left and just unplug and plug back in the 3rd brake light and they worked since.
 
#7 ·
I do not see how a clockspring problem could cause the cluster itself to malfunction. If the cluster malfunctions so that the SRS MIL cannot illuminate, that can actually cause an SRS fault itself. It sounds to me like you have a cluster problem.
 
#8 ·
i checked for corrosion under the driver side carpet and found dust but no change when wires moved around. I unscrewed the connectors by the battery in the prefuse box and tightened them back up. Did the same for all ground wires i seen. I replaced the Cluster fuse also. I wish i can put up a video on here with the issue but i think i will list it on youtube and post a link when i can actually record it because it only happens whenever it feels like it.
My only issue is that everything operates normaly and then the cluster loses power the Comand display and the Climate display lose power for split second. Maybe there is a relay Common relay for these units?
 
#13 ·
Yesterday i unplugged the wire under the airbag for the steering controls but they made no difference since i still had the issue today. Next i will unplug the comand fuse see if that could cause the power loss. This weekend i intend to take the clockspring apart and check to see if there is any damage since there is a issue that the scanner read about the steering angle sensor. Any instructions or things i should pay more attention to? I'm also going to replace the turn signal switch since it doesnt hold in position
 
#21 ·
after driving it during the day and parking it in the garage its about 12.4- 12.5
in the morning usually 12.4
with the car on its anywhere from 14.0 to 14.3

today im going to get a car charger and cut the wire and connect it to a voltmeter so i can check when the cluster resets if the voltage drops because the screen on the comand and screen on the climate lose power for a split second.
 
#22 ·
today while driving to work on the freeway the cluster stopped working and had a few warning lights stuck on witch doesn't happen offten so i started recording and after like a minute it reset again and went back to normal. I uploaded it on youtube. Notice even the odometer and lcd are blank and just the backlight on them is lit
 
#24 · (Edited)
is there a way to check if the clock spring or steering angle sensor is at fault before i buy a cluster and pay to get it reprogramed? If its the cluster I Just can't understand why the SRS light turned on and then i had to clear the code and a week later it came back on thats why im inclined to think that the clock spring might be the issue even if the steering controls work and remember i had that steering angle sensor code come up when i erased the srs code. Would Star scanner say exactly where the problem is cuz then ill go to a shop and pay for them to diagnose it.
Thanx keyhole for the great help u provide. I see your posts almost on every thread. Great Work!
 
#29 ·
Just noticed that if the car is on or key in position 2 where everything is on and the cluster decides to reset then the headlights turn On for about a second and then off even if the lights switch is off ( 0 Position ) I'm about to rull out any issue with the cluster since the lights turn on and the comand and climate screens turn off for split second and voltage stays stable. Also my outside temperature is about 10 degrees Fahrenheit higher than regular temperature. Hopefully the Star diagnostic tool figures it out on Tuesday.
 
#30 ·
I took a look at the function of the clock spring (A45) by studying the circuit diagram - I have never really understood it's purpose. I believe that it is used to maintain electrical connection with parts on the rotating steering wheel with fixed modules on the column. Specifically:

a) horn button
b) driver's airbag squibs
c) left & right multifunction buttons on the steering wheel.
d) steering wheel gear shifter (CLK55 only)

Intermittent failure of those circuits would give an SRS warning, I believe. Is there something that can be sprayed there with aerosol circuit cleaner?
 
#31 ·
i had to replace the clock sprint on a lexus is300 a few years back because the horn would not work. I don't have the issue when i turn the wheel. turning the wheel doesn fix or cause the problem. I'm thinking is further down the line since the issues in the cluster differ each time and there are mor systems that act up like headlights that i just figured out, comand and climate control LCD's. Is there a relay that turns on and off power to the units when door opened or when car goes to sleep? I'm new to Mercedes cars and others have sugested CAN BUS but i don't even know what or where it is, or maybe the can bus has a relay that has corrosion on it and loses power briefely.
 
#32 ·
The CAN bus is like a computer network - it's just a series of wiring that allows different electrical components to communicate through a single pair of wires. My favorite way of explaining the CAN bus is this. Think of all the "stuff" in your driver's door - four window switches, door lock button, that door's lock, the side view mirror, the window, and the power seat controllers. If each switch position needed a wire to communicate with the rest of the car (i.e. seat control to seat motors, window switches to window motors, etc.) then you'd need quite the bundle of copper coming out of the door. However, instead of that, there is s small computer in the door called the door controller. All the wiring from all those "things" in the door connect to the door controller. It supplies power or reads switches. It then has just a single pair of wires, like a computer Ethernet cable, that talks to the rest of the car. So, when you press the button to raise the seat, the button tell the door controller to send a specific signal over the CAN bus. The seat controller listens on the CAN bus, hears that signal and then moves the seat accordingly.
 
#34 ·
Correct - the CAN bus is just a series of wires that connect these parts. There are a few CAN bus "hubs" in the car, that are basically just wiring harnesses for various feed that come together. One such hub that can sometimes cause problems is the one located under the driver's side door sill. If the car gets flooded with water, it can corrode that connector.
 
#35 ·
The car nas never been flooded but it did have corrosion on some tail lights and brake lights contact between the bulb and light
I looked under the door jam and it looks like a billion wires but no sign of corrosion on the 2 long connectors that connect the few wires. im going to the store to get some electrical connector cleaner and am going to spray on them just in case. I drove around with fuse #64 disconnected and the problem is still there. Now I'm looking to find a way to disconnect the climate control and check if that is the issue becausei found lots of soda an coffee w while back when i took the comand off to clean it due to sticky buttons.
 
#36 ·
just cleaned every connection i taught of with electrical cleaner specifically made for cleaning wire connections on cars, including the whole harness under the left door jam. Sprayed all grounds and all plugs. The issue has worsened. Now every time the car goes to sleep the LCD doesnt come back on when opening the door, just the back light comes on. Also the lights flicker more and it only getting worse. Hopefully the STAR test can figure out the exact problem on thuesday
 
#38 ·
Isn't there anyone in the US that repairs MB clusters? I am sure that in the UK we can get SAMs, clusters, etc., repaired and returned by postal delivery.

Otherwise if you buy a new one, your odometer will read the wrong mileage. It is stored in a chip on the cluster.
 
#39 ·
i have a bad cluster in the C240 and I've done a lot of research on these things. In the USA, there are really only two types of cluster repair services - repairing the fading LCD panels, and "correcting" mileage. If you purchase a new "virgin" cluster, it can be SCN coded via SDS and "married" to the EIS and thus have a proper mileage reading on the odometer. If you install a used cluster, it's coding won't match the EIS and you'll get '------" on the odometer. Some DIYers have been able to swap the EEPROM chips (assuming they are functional) from their old cluster to a used cluster and everything seems to work. I have heard of people taking a used cluster and having its mileage zeroed, then being able to use SDS to "re-marry" it to their EIS.

Honestly, the only "certain" fix for a bad cluster is to have the dealer replace it with a new one.
 
#40 ·
bought a used unit and sent both of them out for the mileage to get transferred over to the other one. I plugged it in before to make sure it's the right model but didn't have the guts to drive it around for a bit since i didn't want to mess anything up. Car is parked for now and hopefully by end of next week i'll have a good cluster after spending almost $600 for everything ($110 for diagnostics, $135 used cluster, $300 to get the mileage switched over, and $30 shipping) I didn't want to drive like this any more because i guess due to cold weather the cluster acts up more. Usually in the morning since it got a little colder the cluster would act up like 5 to 10 times and almost never at lunch or after work when it would be sitting in the sun. The only time i had issues in the afternoon was on weekends when the car would be sitting in the garage. I will update the post later when I get the cluster to let everyone know how it went and if the issue was solved. For now thanks a lot for all the ideas and the instructions.
 
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