todd5854

Hey guys. I have a 1994 E320 sedan, and the ASR and ABS lights are always on. car has 210,000 miles. I bought the car with this condition a week ago. During the test drive, everything went smoothly. I drove the car home (hour and a half drive home), everything was fine, and that night, it went into what I searched for, and is known as "limp home" mode. This isn't my daily driver, I bought the car for dirt cheap hoping to turn it around and sell it for more.

I did tons of searching, some of the W124 owners said their ABS and ASR lights come on intermittently, when they hit the brakes, or whatever. My lights are always on. Since I took it home that night, limp mode has been going on within either a few seconds of accelerating, to a few minutes. It's been random.

If I turn the car off and turn it on again, the lights are still lit, but it stays normal for a little bit before going into limp home mode.

Apparently I can replace a switch under the brake pedal, and it will more than likely make all of this go away? How likely is that switch to fix my problem?

Thanks.

todd5854

No one? Really??? Am I the only one who is experiencing these problems?

Jim's500E

Did you check one or both of the speed sensors up by the front shock towers?...if one was left un-plugged, those lites would stay on. Typically folks un-plug them to do burn outs or track the car (so the ASR doesn't interfere with the fun).

If the car goes into LH mode, then there is a short somewhere, could very well be due to the upper wiring harness. They are known to have problems with the plastic wiring coverings degrading, causing shorts which puts the car into limp home mode.

Could also be the TBA, throttle body actuator...it's a pretty costly part to replace also (1000$+). But if it were me, I'd look at the upper wiring harness first off (look for a sticker with a build date) . It's easy to replace yourself on the 6 cylinder cars if it is the original equipment...

Also, if none of that fixes the problem, look at the neutral lock-out switch on the tranny. They go bad too. Unfortunately, tracing down a LH problem can be costly and troublesome as the codes thrown don't usually point to the problem with this vintage car. Good luck with it .

fredtga

also, don't forget to check your battery and see if the alternator is charging properly.

I had a case of all-the-time-low-voltage on my 300CE and usually ABS light was coming on. My car did not have ASR but i'm pretty sure ABS and ASR are tied together so if one system fails the other gets disabled.

It turned out to be the voltage regulator which is a common issue on these older benzes. So, check that out too.

todd5854

Alright, it's been a week since I posted this. The car hasn't gone into limp mode since, so I think its safe to say, hopefully, that it's not the throttle body actuator. Is the upper wiring harness another name for the entire engine harness? Or is there a specific harness just for ASR/ABS? Where can I physically locate the ASR harness on the car? Where is the best place to buy the new harness? Will the build date be on the main pigtail, or just a part of the wire?

Thank you so much for your response, I have a lot to look for now. Sorry for all the questions, but now I know what to look for next time the car acts up. My OVP has a good fuse, I checked that. I'll check the regulator next, I imagine there is specific procedures to properly test both.

Plutoe

The one big thing that you will learn is that most owners of older MB do not know about the systems on their cars let alone take the time to learn, because without that basic understanding you will be spending long hours trying to fix a problem.

First the ABS system and the ASR system are different systems with separate control modules. Because your car has a CAN system sensor information is shared and used by different control modules. A good example is a speed sensor that signal is used by many modules and if it can't receive the information a fault develops.

The other thing you must recognize is that the typical OBD scanner can't read MB B and C codes and the ABS and ASR fall in that category, therefore when your ASR stays on its telling you that there is a fault, but where----that takes special software to find the fault. The ABS is also in that category and some what more dangerous because the ABS system will not function in that state----thats an unsafe situation.

All your issues can quickly be defined cleared and resolved with an MB indy with good software---otherwise you are left to the I think so or its gotta be that or have you tried this approach!!

todd5854

Basically since both ASR and ABS lights are on, I figured it had to be a problem like you mentioned, such as a wheel speed sensor, or a brake pad sensor. But the above reply suggested that because the car goes into limp-home mode sometimes, that it could be my harness. I guess there's also a chance that the ASR and ABS malfunction is two separate problems.

Plutoe

Run do not walk to Ace hardware!!

todd5854

Could you explain that a little better?

Stevester 500e

Todd5854,

Did you ever solve your problem?
I had all the symptoms except limp home mode.
My ASR and ABS lights still come on.

I had an old harness on my car, so I started there because I was planning on replacing it anyways. That didn't solve the problem.

I will now look at the speed sensors. And then maybe my voltage regulator.

Just wonder what solved you problem.

Regards