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Marty, Mercedes Technician
Category: Mercedes
Satisfied Customers: 53775
Experience:  Bosch Certified Master Tech. Over 35 years experience.
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What will cause the back light of the cluster to go out and

Customer Question

What will cause the back light of the cluster to go out and blow the 5 amp fuse after someone charge your battery when it was dead? I replaced the cluster and it took that light out too but didn't blow the fuse. Can you please assist me on this matter?
Submitted: 1 year ago.
Category: Mercedes
Expert:  Marty replied 1 year ago.

Hi, my name is***** the battery was charged with the cables connected it could cause the problem with the instrument cluster. When charging the battery the battery cables should always be disconnected from the battery to prevent any surges in the electrical system.

Expert:  Marty replied 1 year ago.

If your replacement cluster also has no back lighting I would say that your replacement cluster is bad.

Expert:  Marty replied 1 year ago.

You should check fuses 79, 84 and 85. All of those fuses power the instrument cluster.

Expert:  Marty replied 1 year ago.

You can also try rebooting the vehicle network by disconnecting both battery cables and connecting the two cable terminals together for 5 minutes then reconnect them to the battery.

Expert:  Marty replied 1 year ago.

Let me know if you have any questions.

Please remember to rate my service when you are done.


Customer: replied 1 year ago.
Hello Marty
Thank you for your quick response but the replacement had a backlight on the cluster for about 2 days then it bleeped out. Now before the battery was recharge my original cluster worked for about a 4 days then that flicker out.
Expert:  Marty replied 1 year ago.

Hi, did you install a new or a used cluster?

Expert:  Marty replied 1 year ago.

If you installed a used cluster I think you just got a bad cluster. You should check the charging system voltage and make sure that the system is not overcharging. Other than an overvoltage situation there is nothing that will cause the back lighting to fail.