Abs/speedo

[Iain the gadget]

1994 C180

Have only glanced thru posts as yet and not started pulling bits apart on the car.

I have a non working speedo and an illuminated abs light. Could they be connected in some way? I have bashed the speedo housing just in case it had the sticky needle but no difference.

Has anybody had similar problems to the one I describe?

 

[C220GJS]

You probably have a faulty abs sensor ,one on each front hub and one on the rear differential housing. The speedo gets its signal from the abs system as an average of the signals from the three sensors but if one is faulty it breaks the loop,hence no speed signal and an abs fault light.

 

[Sprint'n'Go]

I recently disturbed the ABS sensors on the front of my van during replacement of some adjacent components. I was suprised to see that they were just a push fit and not a particularly tight one. Check that your abs sensors are close to the serrated abs rings, almost touching but not quite otherwise I doubt they would get a valid signal and this will upset both the speedo and the ABS. Worth a look before anything else I reckon.

 

[Iain the gadget]

Thanks Guys.
I'll check in the morning and get back here.

 

[Iain the gadget]

I'll be checking all connections this morning. But it will be handy if anybody knows which sensor doubles up as the speedo sender.

 

[C220GJS]

As I said in my first post;the speedo gets its signal from the abs system as an average of the signals from the three sensors but if one is faulty it breaks the loop,hence no speed signal and an abs fault light;so any one of the sensors could be faulty ,you will just have to check them all. First check all the wiring connections are secure.

 

[Iain the gadget]

All connections fine and dandy!
Perhaps it needs the obd treatment!

 

[Iain the gadget]

Checked all connections and everything appears OK.
Anymore suggestions? I have had the ecu read and there are no codes showing.

 

[eric242340]

hi, The front left speed sensor affets both systems. If you stand at the front of the car its on the weel to your right and its a common fault.

 

[television]

hi, The front left speed sensor affets both systems. If you stand at the front of the car its on the weel to your right and its a common fault.

No reason to be the laft hand one more than any of the others,other than the fact that the left hand one takes more of a hammering on RHD cars.

Malcolm

 

[eric242340]

i cant be absolutely sure for this model but certainly on the S Class each wheel speed sensor has dedicated tasks and the speedo is front left.