ABS,ASR, Speedometer
 

a friend bought (as is) 1996 C280 which has the following problems:

1- ASR, ABS lights always ON when engine is on. although car does NOT go into limp mode and both systems are working.

2- Speedometer won't work.

3- Odometer frozen at certin milage.

the dealer told him it is a faulty ASR control Module. so he bought a used one for $500 and nothing changed.

any idea??????

Check to see if the left front wheel speed sensor is connected, if it is you may want to test the sensor and it's voltage output.

800 to 1400 ohms resistance
>700mV AC while spinning

thank you MrCjames, well check that.

by the way where do I find the OPR in the 1996 C280 ???

All of your symptoms except one lead me to believe you have a speed sensor problem.

The one symptom that messes it all up and suggests an ECU problem is that the light is on and "both systems are working." That is about impossible. I'm guessing you are wrong when you say they are working. If not you have two problems: one for who is turning on the light and two for why the controller doesn't recognize the light is out of its control. The controller will not work with the light on or disconnected.

Have you tested the ABS on some wet grass? Does it work? What other evidence do you have of it working since it is a non intrusive system. Does the traction control triangle light when accelerating on wet grass?

Steve,

what you said makes sense, actually I wrote what my friend told me, but I'll take the car for a test drive tomorrow and I'll confirm if both systems (ABS and ASR) are working or not. by the way the car is 1994 and not 1996 as I mentioned before.

Steve,

sure enough what you said is 100% TRUE. Both systems (ABS, ASR) are NOT working. I just tested both as you suggested on a wet grass.

so that means it is a speed sensor problem, right? any idea how much it Cost for 1994 C280???

is it hard to replace? or does he have to take it to the dealership?

thanxxxxxx again, for the valuable info. I really appreciate it.

You need to be sure which one is out. As mentioned above one of the front sensors is used for the speedo on ASR cars. On ABS cars the differential sensor is used.

Steve, you lost me :cool:

my understanding is, there is more than one speed sensor!?
and I have to check which one is out.

could be the front wheels or on the differential?

3 sensors? right.

is the car fixed?
 

Always frustrating to read these threads when you have a similar problem and it gets to the end with no post as to whether the problem is fixed! Not giving you a hard time, just really wanting to know :-)

Can you tell me if the speed sensor fixed the problem for you and if not what did you do to fix the ASR and ABS lights being on?
Thanks!
John