ABS light on all the time, I have read that OVP is faulty, yes or no? - PeachParts Mercedes-Benz Forum

ROLLGUY · #1 01-26-2015, 12:39 AM

1993 190E (yes I know this is the Diesel section, so I will call it a 1987 190D if the OVP location is the same and the ABS system works the same

). The ABS light is on all the time (car driving or stopped). I have read that most times the OVP relay is the culprit. My question is: Where is the OVP located on a 1987 190D? Is there another place I should look for a fault other than the OVP? Can I assume that if the fuse/s are blown then I have found the problem?

tjts1 · #2 01-26-2015, 12:48 AM

Its behind the battery hidden by a black plastic cover. You can pull the cover straight up without removing the battery.

Mxfrank · #3 01-26-2015, 12:59 AM

Sometimes it's the OVP. Is the tach working? Is your idle always steady? If so, then maybe not.

I've also had the ABS light due to...wait for it...a problem with the ABS system. Specifically, a bad sensor.

I know of no test that will accurately determine the status of the OVP, other than replacing with a known good OVP. But you can measure the resistance of the ABS sensors, the correct numbers should be in the FSM. Also, the front ABS sensors tend to pick up a lot of magnetic debris over time...it's worth pulling them and cleaning them up.

Jeremy5848 · #4 01-26-2015, 01:10 AM

Have you tried the ABS system to see if it actually works?

ABS light on all the time generally means there's something wrong with the ABS system. Check the front ABS sensors to see if a wire has been cut or otherwise broken. Remove the two front wheel sensors, see if they are dirty or if the tooth wheel (look in the sensor hole w/bright flashlight) is all crudded up. Rear sensor (on differential) is usually OK but should be checked if fronts are OK.

If OVP has failed, tach will not work. OVP also powers ABS so the light might not work at all if OVP has failed (can't tell from schematic).

ROLLGUY · #5 01-26-2015, 09:25 AM

I have read that the ABS light only illuminates if a sensor is bad after the vehicle is moving. The consensus is that if the light is on all the time, it is NOT a sensor. However, I have not pulled any wheels and checked the sensors. I also don't know if the tach works, I will have to ask (the car belongs to a friend of mine). If in fact the tach does not work, I now know the first place to look. She did say that another friend worked on the brake lights (re-wired or something with a bulb), and the ABS light has been on since. The brake lights do work as they should now, but I don't know exactly what was done to make them work, or if the work is related to the ABS light.....Rich

tjts1 · #6 01-26-2015, 09:30 AM

On my 93 2.3 I have an intermitant ABS light but I've only see it on when the car is not moving.

ROLLGUY · #7 01-26-2015, 02:17 PM

I found out today that the tach is in fact working fine, as well as the idle. Even though I can't see why it would help to clean the sensors (from the way I understand how the system works), that seems like an easy enough job to do. I have to replace the radiator on this car in a couple weeks, so I will add the sensor cleaning to the list, and let you all know what I find out......Rich