I have a 1995 W124 e320 with an odd problem. The check engine light is not functioning at all. Does not come on at start up. Also the ABS light is always on. I have gone through the abs system quite a bit and have not found any problems(sensors, relays, brain, resistance for front lines). My mechanic says it may be the diagnostic module aka the CARB unit. Have not checked the wiring harness, where does one check it? thanks everyone.

have you checked your OVP? those things cause all sorts of oddball problems

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hum.....
1987 300TD 311,000M Stolen. Presumed destroyed

That was my first thought. However, doesn't the tach usually drop out ?and rough idle, etc.? I thought the problems would be more severe if the OVP was failing.

Never hurts to check them they do cause oddball problems, but yes that is a possibly symptom

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hum.....
1987 300TD 311,000M Stolen. Presumed destroyed

Have you owned the car since new? If no, then maybe a previous owner pulled the bulb out for the ck engine lite. You should be able to pull the code up for the abs.

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Jim

There is a small button on the diagnostic plug just forward of the battery (in CA cars w/ CEL). Turn the key on, hold this button down for 4seconds, release, does the light next to the button flash?

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Gone to the dark side

- Jeff

Checked the diagnostic flashes. Nothing. No light the whole system seems to be dead. So, ovp or carb unit. Both not cheap. Wouldbe nice to figure out instead of buying both. Checked bulb in dash it is ok.

Start with the OVP, IIRC there are two circuits in the '95.

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Gone to the dark side

- Jeff

Im sorry what is IIRC? pulling the fuse on the ovp has no effect on the engine, even while its running. If that helps

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1995 wagon, 1995 e300D, 2001 e320

Found an ovp and tried it today. Let's file this one in to the many idiosyncrasies of the ovp file...., problems fixed!

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1995 wagon, 1995 e300D, 2001 e320