Today, while driving down the freeway my ABS light went on for a few miles, then went off and immediatly my CEL light came on, vehicle ran fine. The CEL light went off and immediatly the ABS light came on, for a few miles, then went off and immediatly the CEL light went on and stayed on. It went back and forth like this several times with both lights going on and off at times. over a 100 mile trip. I ran some errands so that the car was shut off for a few minutes and the CEL light would stay on when I restarted the car, and after a few miles the CEL light would turn off and immediatly the ABS light would go on. I have not been able to check for codes yet, but I recently had the instrument cluster out to replace a ignition switch that was intermittantly getting hot, I also serviced the battery terminals when I replaced the ignition switch [not the IGN. lock cylinder].

Could this be a OVP relay issue?? The vehicle seemed to start [hot] and run fine.

What is the proper way to check for ABS/CEL codes on a 1990 190e 2.6 california model? I understand that there is a different way to check for codes unique to the 1990 California 190E.

OVP almost dead positive. First check the fuse on top, then replace.

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2016 Monsoon Gray Audi Allroad - 21k
2008 Black Mercedes E350 4Matic Sport - 131k
2014 Jeep Wranger Unlimited Sahara - 62k
2003 Gray Mercedes ML350 - 122k

OVP good place to start

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1986 300SDL, 211K,Dealership serviced its whole life
1991 190E 2.6(120k)
1983 300D(300k)
1977 300D(211k)

I checked for CEL codes and got 18 flashes which appears to be a "Air Control Valve voltage illogical" error. I do not know how to retrieve ABS codes.

The OVP will not give a CEL "code". If you are getting error codes, then that is another story that needs to be resolved.

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2016 Monsoon Gray Audi Allroad - 21k
2008 Black Mercedes E350 4Matic Sport - 131k
2014 Jeep Wranger Unlimited Sahara - 62k
2003 Gray Mercedes ML350 - 122k

I have confirmed that my OVP relay is intermittant by tapping on it with a screw driver handle and watching the IACV cut in and out consistantly with me tapping on the relay. In 20 years of owning this car it has never had a ABS or CEL light come on when driving [only on prove out] and all of a sudden one day both lights come on. I have ordered the correct OVP relay from the local M/B dealership and will install, road test and report back.

Mean while I have pulled all three of my ABS sensors and cleaned them, confirmed the IACV operates with 12v applied, confirmed IACV continuity to the CIS-E control unit and confirmed no shorts circuits from the IACV coils and housing. And replace my front and rear Flex joints and installed a rebuilt/rebalanced drive shaft assembly [new u-joint and center support bearing] replaced the power steering fluid and filter and cleaned the ABS relay contacts.

I put the new OVP relay in a went for a 20 mile road test in 104F tempuratures. The car ran great and no ABS or CEL lights. Appearently a bad OVP relay can set a code 18 on a 1990 190E 2.6 A.T California model.
By the way the Replacement OVP realy from the M/B dealer was the type with two[2] 10amp ATO fuses in it. Part # 210 540 37 45
The old OEM relay was part # 201 540 32 45 with a date code of 10/09/89.