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96 SL600, 07 BMW M5 ,04 545i sold, 2013 C300 Sport (for wifey) 03 CL55 s/Chg sold,91 500SL, sold
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Discussion Starter #1
Hello Folks...I was wondering if anyone that currently or ever did own any mercedes w140 body or R129 series experienced the dreaded flashing instrument cluster lights or dead cluster issue.I know there has been numerous post on fixing the cluster by changing the 3 capacitors on the circuit board.I am aware of that and I did mine years ago, that fixed my temporary blackout/malfunction issue whenever I used my turn signal.My question is that recently I had an issue with my battery and alternator upon which I changed both.Just before changing them I started experiencing the flashing lights/dead cluster issue again.Only temperature gauge works.Does any one know what else was changed their cluster beside the capacitors? Something else such as a power regulator must need changing but which one?Any ideas?..Yes, I did try to change the capacitors again.But this time no luck? Secondly does anyone know or have the wiring diagram for the cluster.Mine is a 91'500sl but I think it will share certain common traits with it's siblings.Any help will be appreciated.Thx.
 

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Hey MBRider, I had this same problem with my 92 500 SL took it to Ultimate Benz in Lithonia Ga. they fixed the problem by replacing the fuses. Note that the fuses were not blown just bad.. the Capacitor was not the problem, had it replaced first. Hope this helps you and Happy Benzing!!!!!!!
 

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Just posted close to the same issue 3 minutes before yours. Hopefully someone has a response. I have replaced fuses as suggested and even replaced the cluster with no fix, so it would appear there is something more that could cause this issue.... as I stated in my question to the forums it occurred after the battery was dead and had to be charged... your failing alternator and battery make me wonder if there is a connection between our rather identical problems... Hope someone comes up with a fix.
 

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96 SL600, 07 BMW M5 ,04 545i sold, 2013 C300 Sport (for wifey) 03 CL55 s/Chg sold,91 500SL, sold
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117 Posts
Discussion Starter #4
Yea,I checked my fuses in the engine bay by the fender all are good.I even had them all replaced about a year ago..I detected that my battery kept draining overnite for no obvious reason.After weeks of sleepless nights and a million test.I finally traced my battery drain issue to the back of my alternator.There are two wiring harness stems on the back of alternator.One screws on harness that comes from the battery in the trunk and the other goes to the car's electronics/computer including the instrument cluster.Without proper contact one the small wire/stem my alternator was not getting good ground..This caused it to have the drain overnite.It was only when I decided to take the alternator out to get replaced did I notice that the contact on the back of the alternator was not sitting flush.This is the little stem that the smaller wiring harness hooks up too..The nut that holds the actual stem from the alternator was not tight enough.That fixed my issue after getting a new alternator since I had a lifetime replacement.I just sent off my cluster to a repair center in Massachusetts today.I will keep you guys posted on what parts were changed or repaired.Hopefully that will help shed some more light on our cluster issues.
Thx.
 

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96 SL600, 07 BMW M5 ,04 545i sold, 2013 C300 Sport (for wifey) 03 CL55 s/Chg sold,91 500SL, sold
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117 Posts
Discussion Starter #5
Well folks,I needed to update everyone on my findings.My R129 cluster as I stated was sent for repair.I got a call from the repair center that apparently my circuit board was damaged and beyond repair.The service center had another cluster which they sold me.I was glad to get another cluster but soon realized another issue.The cluster that the service center sold me had two issues 1) Erratic or jumpy speedometer and fuel gauge reading was wrong by about 1/4 tank more? I immediately suspected that this was probably for a W140 body or needed calibration? I sent it back to the service center and they checked it and found no faults.I even opened up the unit and found a R129 sticker on the circuit board but not sure why my speedometer was jumpy and wrong fuel reading.This actually caused me to run out of gas one night just 3 blocks from home..You can guess how frustrating I was! I then decided to either bite the bullet and order a new one from the dealer for $998 or try to find another used one online.I took the chance and picked up one online which now works perfectly.So to summarize the issue, my original cluster could have been repaired by just changing the three capacitors on the circuit board.If that does not fix your issue,then you most likely have a damaged circuit board like mine which may not be repairable.Hope this info helps someone.Good luck.Thanks to all the members that contributed to this thread.
 

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Greek God of the R129
SL500-500SEL-190E
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Are you aware that are odometer places that repair them?
For something like $200?

Regards,
aam.
 
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