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Hello all, Recently i came into acquisition of a wonderful 2005 CLK 320 (Pre-Facelift) and one of the first issues i noticed was that not all of the LEDs in the Instrument cluster come on when the rest do. This leaves my IC looking very "Spotty" and becomes annoying to look at after a little while. there are no other electrical issues in the car. I have pulled the fuse on the drivers side fuse panel and it has not blown or shown signs of corrosion. What would be the next step in diagnosing this problem? im completely new to MBZ's so im a bit overwhelmed and am looking for direction
**Followup* - I replaced my battery a week ago with a brand new one so it couldnt be that
Last edited by RalphieN; Jan 23, 2020 at 09:08 PM.
Reason: Supplemental Information
The back-lighting for the cluster is a series of LED's surface-mounted on a flexible Mylar circuit board. It's almost impossible to repair without the proper soldering tools, but there are shops that specialize in this sort of thing. If you do send the cluster off for repair, just DO NOT drive the car with it out because the odometer is stored both in the cluster and ignition switch. A mismatch will cause a loss of the odometer reading and getting it back is VERY difficult.
The back-lighting for the cluster is a series of LED's surface-mounted on a flexible Mylar circuit board. It's almost impossible to repair without the proper soldering tools, but there are shops that specialize in this sort of thing. If you do send the cluster off for repair, just DO NOT drive the car with it out because the odometer is stored both in the cluster and ignition switch. A mismatch will cause a loss of the odometer reading and getting it back is VERY difficult.
So are you suggesting that the individual leds in the the cluster are bad? what could be some other causes so that i can rule out all other possibilities
Rudeney, do you know if odometer is also stored (or not) in the ECU and/or TCU?
No, it is only stored in the EIS and the instrument cluster. However, the VIN is encoded intot he ECU, and for the 722.9, also in the TCU.
Originally Posted by RalphieN
So are you suggesting that the individual leds in the the cluster are bad? what could be some other causes so that i can rule out all other possibilities
LEDs usually don't go bad, so it's probably bad solders where they are attached or it could be cracks int he Mylar circuit board. Either way, it's very difficult to solder on Mylar without melting it.
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