OVP's, ABS's oh the headache

[rocker]

what an annoying 2 weeks. my beloved merc failed MOT for the abs light being on. which started about 3weeks ago, along with difficult starting problems. after lots of investigation and advice from experts, everything pointed to the ovp relay, which i replaced at a cost of £72 from merc (can you really justify a tiny box with a couple o wires and a couple o fuses). plugged it in last night, worked a treat, abs light went out, and engine fired up straight away, so got it booked in for retest today. started the car this morning, back to square 1.
i'm losing my mind as to what could be up with it. if anyone has had the same experiences or even better, can hel pwith the solution, i'd be most grateful.

 

[grober]

You may have a genuine ABS fault of course- check/clean the wheel sensors and associated wiring for damage. However the ABS light will light if the supply voltage to it drops below a certain level. You might just have some dodgy connections somewhere- recheck the OVP socket. Check the new OVP fuse hasn't blown indicating another electrical fault somewhere. The other thing is to check the voltage supply to the ABS unit isn't too low with a voltmeter. Should be comparable to the battery output voltage whatever that is.

 

[jpskiller]

I have this but on a older 190e, used to be intermitent until I tried swapping OVP relay then it became permament (bad wire around ovp somewhere), havent had time to fix before MOT, so on a long shot I pulled the bulb from the cluster, and car passed MOT ok. Gives me more time to try and sort issue out.

 

[BlackC55]

You were booked in with me on Monday so I could have a look.