Another new problem in my CLK. I hope to avoid going to the dealer again (the less it is there the better)
Once I reach about 90km/h the speedo stops moving up smoothly (it moves in bursts of about 5-8 km/h) even though I continue to accelerate at a constant rate. Below 90 is ok. It only does this as speed increases, not if speed decreases, that is it will decelerate smoothly from any speed.
I have gone as high as 160 km/h to test (haven't been on the hiway, only city) and it exibits this behaviour consistantly above 90km/h.
Any ideas ? Could some piece of dirt of something have fallen in there somewhere ? The dash was recently replaced at the dealer.

Was your stereo on during this event?

I have noticed that bass from my speakers in the front dash causes my speedometer needle to jump 3-4mph. IT only happens for me when I am accelerating at speeds over 45mph (top dead center for my gauge)

I don't think this will help, but, you never know.



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Jeff Biesenberger

'84 Euro 300D 261k miles

Thanks, but nothing to do with the stereo. I have had that situation in other vehicles though.

It is my impression that all the instument needles in that IC (inst cluster) are stepper motors responding to a calculated value. That would make me think that the problem is more likely to be the motor than the signal (or the processor). Although poor circuitry could cause the processor to have bad output.

Does the speedo act similarly if accelerating with the "Accel" funtion of the cruise control. If the acceleration is smooth on the cruise control I would presume that the speed signal is good; which leaves the IC. Is it out of warrantee??

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Steve Brotherton
Owner 24 bay BSC
Bosch Master, ASE master L1
26 years MB technician