ABS light on constantly - not OVP
 

1993 190E 2.3 4cylinder auto USA model.

Happy New Year everyone.

For the second time in 2 years my ABS dash light is on all the time.
The 1st time (about 18 months ago) it was accompanied by poor starting.

I rectified this with a secondhand OVP relay (part # 201 540 3745) - this had 2 fuses compared with original's 1 fuse (part # 201 540 3245).

Car has been running fine until 1 month ago; I was driving along and ABS light came on and has stayed on ever since. Poor starting followed - predictably! I checked OVP relay to find one of the fuses blown.

I Replaced fuse - ABS light still on and poor starting. Changed OVP relay for a spare I had (part# 201 540 3245. Starting better-than-ever but ABS light still on. Changed OVP relay for brand new item (part# 201 540 3245).
Result; starting not quite as good and ABS light still on.

Any ideas? I read somewhere the ABS sensors may need cleaning?! My useless Haynes manual doesnt tell you about ABS so can anyone help me?
Also, can anyone tell me where I can download a decent factory workshop manual or equivalent.
Many thanks
Nick

You may want to check the physical ovp plug and make sure it is not corroded or broken in any way first.

The OVP plug is fine. Also took off the ABS sensors at the front and cleaned them and checked the wiring. Everything seems fine.
I cannot find the fuse for the ABS system - any ideas?

Cleaning the front sensors might not fix it. There is a grooved ring in the hub that the sensor is reading. If that grooved ring (looks kinda like a geared ring) is full of junk, the sensors may not be able to read it correctly. Pull the sensor and put a compressed air probe in the hole to the senso-ring and rotate the brake rotor whilst blowing the air - that might just fix it.

ABS voltage
 

If the alternator bushes are at its last end the output is a little erratic and spiky this overloads the OVP .Do clean the pins where it fits
mak