The AutoZone free code reading will not tell you which wheel sensor is gone. They only read generic OBDII emission related codes. You need a Mercedes diagnostic hookup. In my case it was the rear left one that was gone. $ 129.- is the same price Autohaus Az wants for the genuine MB part.

 

Have you turned the steering wheel lock to lock a few times with the motor running?? You should try that first before going future to reset the system. The lights should go off after the reset.
Having your own code reader is very handy. I Have one like this.

 

The code reader you listed will not read ABS, only basic engine codes and transmission codes. ABS is a whole other breed Same for the domestics.

 

I literately just got home from repairing your same issue. Mine was the right rear wheel sensor. My friend borrowed a scanner that would scan Mercedes ABS.

Had the error appear last week or so. Got on Ebay and ordered one front and one rear, about $25 a piece. Be warned the cheap $20 ones are not exact same as the OEM's, the cable is shorter and they do not have the same strain reliefs. Read the descriptions and look at the pics carefully. The rear one was identical and worked.

Yours is most likely a rear. From what I have found and read, if it were a front one than most likely your check engine light would come on and the car would go into limp mode, meaning only reverse and second gear.

 

The dealer wanted $99 just to read codes. Said it would take one to 1.5 hours. I said no thanks. I searched inter web and learned you can test sensors with a multimeter. Where is the end connection on the rear sensors. Under the car or in the trunk? I'm sure once I get under there it will be easy to trace, but direction from someone that's done this will help.

 

1.5 Hours??? I think not. More like 5 mins.

 

The rear ABS sensor wires disappear into the under body via a large grommet. Once you have removed that, there is a connector plug.

 

Went through similar issue with my '05 S430. I have a OTC brand generic scanner which only would tell that it was the left side, would not tell whether front or rear. Found an indy nearby that has a Matco Tools touchscreen scanner with Euro software, that scanner told left rear sensor bad. The guy only charged me $30 to scan and reset everything. On the '05 car the left and right side rear sensors are the same part number, and the front has different part numbers for the left and right, making 3 different part numbers for one vehicle. The cable lead for the rear sensor has a large boot on it where it goes through the floor from the bottom side, mine had water in it.

 

I got AutoZone to read my codes hoping they could narrow it down to right or left side at least but no go. Reader didn't register anything wrong. Not one code. Guess i'll be pulling each sensor and testing one at a time. Starting in rear and hope I can find bad sensor on first try.

 

Tested my rear sensors with multimeter, set to resistance, and didn't detect an issue. Both registered a similar setting. The left grommet was difficult to get back in. Awkward to reach. The right rear grommet had what we in it. Guess it's time to take to dealer and get codes read. Second guessing my multimeter test accuracy.

 

"I got AutoZone to read my codes..."

As mentioned above, the common OBD-II (On Board Diagnostics - Version II) code readers are intended primarily for reading the Federally-required diagnostic codes that affect emissions performance. There are very, very few cheap code readers that have a clue about Mercedes body, suspension, HVAC, etc.

 

The sensors can be good, but not the encoder ring on the shaft. You should fully inspect the ring to make sure each hole is free of debris and the ring is not cracked. It's not that uncommon for the ring to crack on the domestic's, not sure on MB, but would assume it's possible.

 

Where is the end connection on the rear sensors. Under the car or in the trunk? I'm sure once I get under there it will be easy to trace, but direction from someone that's done this will help.

When one removes the rear seat, the connectors for the rear sensors would be clearly visible. Clean them with a suitable cleaner spray before replacing them. It may solve your problem.

Daniel

 

2004 s430 speed sensors

Pulled rear seat out, and rubber covers for the rear sensors were full of water. Drained it , let dry, some WD40 and reconnected and ABS alarms cleared

 

I hope that there were other traces of water under the rear seat. Have you checked the wells under the hood at the base of the windshield for water?

 

I got my codes read at indie shop for $36. All errors pointed to right rear wheel speed sensor. I bought new OEM sensor at dealer for $130. I replaced my sensor and all errors went away.

 

Is this an easy swap? I can’t find anything on replacing the rear sensors

 

Multimeter reads 13.48 M ohms on both front VSS sensors?

While troubleshooting the ABS light on problem I used a Fluke Multimeter at the and found the VSS sensor resistance measured as follows:

Measured at the module connector -
front left 3.48 meg ohm
front right 3.48 meg ohm

rear left 13.1 ohm
rear right 13.2 ohm

Anyone know what the readings should be?

 

Hi,

Around 13 Ohm sounds acceptable, but those readings at the Controller should be the same.

Assuming you are testing the correct pins, I'd say you have a bad connection somewhere in between the 2, probably a rotten or separated multi plug somewhere :wink

HTH

Cheers Dave

 

Hi,

Repeat..........

Hi,

Around 13 Ohm sounds acceptable, but those readings at the Controller should be the same.

Assuming you are testing the correct pins, I'd say you have a bad connection somewhere in between the 2, probably a rotten or separated multi plug somewhere :wink

HTH

Cheers Dave

Or a broken wire

Cheers Dave

 

ABS sensor resistance reading 3.48 meg ohms ?

Hi Dave, Yes, I used very small pins right on the connector that plugs into the module. I was very careful and measured several times. I have a diagram from a local shop (they kindly printed it for me). The drivers side rear sensor is new (the old one was defective reading open).
It's very strange to have both front sensors reading 3.48 meg ohms consistently. Tonight I'll pull a front wheel, check the sensor, and see if I can get the meter readings near the sensor.

Thanks
JK

 

ABS light code P0500 check engine light ohm readings

I used the ohm meter to find the readings at the module connector and the wheel sensors are:

Measured at the module connector and at each wheel sensor (first connector) -
front left 3.48 meg ohm
front right 3.48 meg ohm

rear left 13.1 ohm
rear right 13.2 ohm

I pulled the sensors out and found them clean, down inside looks fine (clean). I rotated the wheels to be sure it was clean 360 degrees (they are all clean)

Ideas / recommendations?

 

ABS light code P0500 check engine light ohm readings

Dave, The reading 3.48 meg ohm for each from wheel is at the module connector and at the closest point I can get to the wheel sensor in the wheel well.
I guess I should have added the following:
FRONT
meter connected at the module and the wheel speed sensor connector plugged in = 3.48 meg ohm
meter connected at the module and the wheel speed sensor connector unplugged = open circuit
meter connected at the wheel speed sensor connector = 3.48 meg ohm
REAR
meter connected at the module and the wheel speed sensor connector plugged in = 13 ohm
meter connected at the module and the wheel speed sensor connector unplugged = open circuit
meter connected at the wheel speed sensor connector = 13 ohm

I also checked each pin at the module for short to ground or +12 volts each (test shows no shorts) this is true for all wheels.

 

Dave, The reading 3.48 meg ohm for each from wheel is at the module connector and at the closest point I can get to the wheel sensor in the wheel well.
I guess I should have added the following:
FRONT
meter connected at the module and the wheel speed sensor connector plugged in = 3.48 meg ohm
meter connected at the module and the wheel speed sensor connector unplugged = open circuit
meter connected at the wheel speed sensor connector = 3.48 meg ohm
REAR
meter connected at the module and the wheel speed sensor connector plugged in = 13 ohm
meter connected at the module and the wheel speed sensor connector unplugged = open circuit
meter connected at the wheel speed sensor connector = 13 ohm

I also checked each pin at the module for short to ground or +12 volts each (test shows no shorts) this is true for all wheels.

Hi,

In that case it looks like you need 2 new Front Wheel Sensors.

HTH,

Cheers Dave

 

I am dubious...

It appears to me that there are two main possibilities here:
1) Both front sensors failed simultaneously in such a way as to change the resistance readings from exactly 13 Ohms to exactly 3.48 meg-Ohms.
2) There is an error in the wiring diagram, in your interpretation, or in the method of testing the sensors.

Based upon past personal experiences, I think that 2) is much more likely than 1).

 

Last night I made up a little jumper. With the ohm meter on the module connector I installed the jumper on the ABS sensor connector near the sensor in the wheel well. jumper on = zero ohm's jumper off = open circuit. I ran this exerciser for both front ABS sensors and got the same results.

So my real question is what should the front ABS sensor resistance be?

 

Hi,

As I said before, I'd expect all 4 Wheel Speed Sensors to all have the same, (well very similar), resistance...........

So say 11 - 15 Ohms would be acceptable.

Why not get the codes read on SDS, and look at Live Data on Wheel Speeds when driving ??

Far more accurate way to determine what is going on, and the Guided Tests should take you straight to the problem.

Or go to a Motor Factors who has a new one in stock and ask if you can measure it's Resistance :wink

If you have a search around the Forum, maybe in the Encyclopaedia I'm sure someone will have put up the Resistances somewhere :wink

If you haven't resolved it in a few days time I'll drop mine down on the lift and measure one for you, as it has all the Wheels off it ATM, but I can't lower it right now because there is a ton of stuff under my lift :laugh

HTH,

Cheers Dave

 

It's not too hard. They can get a little crusted up from years of being on the road, so they might need just a little persuasion.