w123 tachometer - Mercedes-Benz Forum

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post #1 of 4 (permalink) Old 01-25-2009, 10:47 AM Thread Starter
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w123 tachometer

hi. i would like to know why my 230 (w123) won't accelerate or accelerate really rough when i connect the tachometer on the ignition coil. thanks.
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post #2 of 4 (permalink) Old 01-25-2009, 11:29 PM
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I don't think it's supposed to connect to the coil directly, it seems there should be a connector block on the left inner fender with maybe 2 green wires connected together with a phillips screw. We had problems with the tach having a short in it causing the ignition primary signal to diminish to the point the ign. didn't work. Is a stock setup? and what year is it?
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post #3 of 4 (permalink) Old 01-26-2009, 10:24 AM Thread Starter
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it's ok. i worked it out. it seems that the guy that first hooked it up messed the wires and had the power hooked on the signal wire. it works fine now. thanks anyway.
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post #4 of 4 (permalink) Old 04-07-2010, 03:03 AM
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I'm using this method and worked fine. From the behind of tacho unit, connect the (+) to the clock wire (+) and the (-) to the coil (-). It just using one cable to the coil to catch the ignition pulse.

W123 280 1979
W115 200 1976
W124 300E 1991
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