ABS light intermittently flashing (W126) - PeachParts Mercedes-Benz Forum

tinypanzer · #1 04-28-2009, 09:52 PM

For some reason I just seem to be inundated with issues all of a sudden.

Now my ABS light is flashing very briefly and intermittently. What could this be? Wheel sensor? Control unit? Never happened before.....

90 300SE, 123K

Any direction greatly appreciated.....

duxthe1 · #2 04-28-2009, 11:48 PM

Check the charging system. When the system voltage is low, the ABS is the first to have problems. Usually you will have the ABS light on before the battery indicator light when you stop charging. If it were an abs sensor I'd expect the light to stay on, not flicker. If the charging system checks out, even under load, then double check your OVP relay. Post back if you havn't fixed it by then.

sranjesuper · #3 04-29-2009, 03:22 PM

check your brake fluid reservoir. Although it is one reservoir, There is 2 little reservoirs inside and both have to be on the same level with brake fluid. IF one looks like it has more than the other, top it off until they are the same level

tinypanzer · #4 04-29-2009, 05:36 PM

Thanks, I'll check those things.....

Here is some more info... First, I just replaced my OVP last week with a brand new one. I wonder if it has issues.

Secondly, it appears that I am either losing engine power when the light flickers on OR, the brakes are engaging. Hard to tell, it happens so fast. But, I definitely feel a brief loss of vehicle speed when the light comes on. It never seems to come on for longer than a second....

What would be the best way to test the charging system on this car?

Thanks much!!

duxthe1 · #5 04-29-2009, 09:19 PM

Turn on all of your lights and accessories and measure the voltage present at the battery. Leave it running and check again in 5 min. Sometimes, with one bad diode an alternator will charge around 10 to 11 volts, enough that you're not totally stranded but the electrical starts to get goofy. Alternately your voltage regulator may be in the early stages of failure. I may be way off base but it is good to rule out the charging system before diving into a full bore diagnostic on an ABS system without fault memory.

tinypanzer · #6 04-29-2009, 10:25 PM

Oh, so test it just like any other car...... Duh.... Okay, I thought there might be some specific way on this car.....

Anyhow, I am going to test that as well as open up my ABS relays to see if there are any solder joint related issues. Luckily I snagged a spare set of ABS relays from a boneyard this week........

Thanks!

Addbhp · #7 04-30-2009, 03:35 PM

The same thing happened to me about 6 months after I bought my used 300e, I left it for approximately a year. Then the light came on more frequently until one day I was left stranded, with the car losing all electrical and then power while driving. I ended up replacing the OVP, and then the Voltage regulator. I think it had to do more so with the voltage regulator, as comparing the new vs. the old, the two bushings were so worn, it's a wonder I had any charge at all.

I doubt its the ABS at all.

tinypanzer · #8 04-30-2009, 04:09 PM

Thanks for sharing your story.... I am beginning to think that at $35 I might as well just replace the voltage regulator on general principle. Heck, 123K miles is a lot for any alternator, especially one that runs in such a high RPM beast like a 300SE. It wouldn't surprise me to see the brushes worn to a nub.

My OVP is about 2 weeks old, so unless it is defective I don't think that's my issue.

Thanks again!!

tinypanzer · #9 04-30-2009, 05:35 PM

Well, I bit the bullet and bought a voltage regulator. Gonna put it on tomorrow.

Then, in a test of courage, I am going to drive it to North Carolina and back this weekend.

I guess I will find out soon enough if that is my issue.

Pray for me!!

tinypanzer · #10 05-04-2009, 04:10 PM

Addbhp - I think you were spot on in your diagnosis. I put a new voltage regulator on my car Friday, and then proceeded to drive it a thousand miles this weekend, to North Carolina and back with absolutely no issues. Many many thanks, my friend. The trip was quite urgent, and there were no rental cars available, so I had to take my 300SE. I had my mom in the car the whole time too, so a breakdown would have sucked.

Thanks again, you really saved me some grief.

DrFrizog · #11 07-06-2009, 01:17 PM

it's always the battery, everything else is fine but the battery is aging then the abs light fgoes on

RSA560 · #12 07-09-2009, 10:50 AM

Excuse the hi-jack, please.

Guys, my mother's 300 E has for a few yrs lit its ABS light upon cold start-ups - very seldomly, maybe once every 2 months.
It would light for a few seconds during which time the engine would stumble at around 500 rpms. A quick rev used to sort it out quickly. More recently it would happen on a weekly basis, but now the car would stall and would have to be restarted and revved a few times to get it going. The light only ever comes on upon start-up. Otherwise its running fine with a new alternator and battery.

Could it be the voltage regulator or what?
Its due for its 250 000kms lube service and I want to ask the mech to replace whatever you guys think is necessary or could rule it out.

Thanx a mill