craft1

Well I havent posted in awhile but I need some help. last time I had issues with a s class can problem, now I have a esp issue.

anyway, about 2 months ago I purchased a 2001 c320 from a private seller. got it cheap and it was in good shape. well about a week ago my esp, bas, and abs lights came on. it would say bas unavailable, esp unavailable, and ABS visit workshop.

Well I took the car to the dealer to have them check it out.

anyway a few days later I got the car back and they replaced the left front wheel speed sensor. But about 2 miles from leaving the dealer all the lights came back on, esp, bas, and abs visit workshop. so I took it back and left it.

so I have been calling the dealer for the past few days now and each time they keep telling me they havent figured it out yet. So today I went up there and talked with the team leader of the tech who was working on the car.

he showed me the short test they had ran and it looks like this

ETC: code 121 the left front wheel rpm signal transmitted by control unit
n47-5 (esp, sps, and bas control module) over the can bus is intermittently
implausible.

ME-SFI 2.8: P20cb-008 no can message vehicle speed signal left front wheel from control unit n47-5 esp control module or message faulty read fault memory of control unit esp p1999

ESP: c1100-016 L6/1 left front speed sensor implausible signal

BAS: c1025-002 can bus: can message abs is faulty

and they said besides the new left speed sensor they installed a new esp control module and the light still came back on. so now they are stumped.

they said they checked the relucter ring on the hub and said they was a small section with a bit of mud, but it shouldnt effect the reading.

he then said I might have a wiring issue somewhere. he also said he checked for any related bulletins and tac cases, but said nothing match this complaint.

they havent ask for any diagnostic time since I paid a few hundred dollars for a new sensor. but my car has been there for a week and nothing.

Thought I would ask for some help. maybe from anyone who has experience with this.

thanks.

sosh

Guess thats why you got it cheap!!

MBTech21

SOrry been away!!
FIrst, abs/bas unavailable is not a fault- it means the steering angle sensor is not initialized. So they but a wss, and now there is a t fault- it has to be the sensor or the reluctor ring. SOunds like they put the wrong one is- we switched types of sensors around then, they plug in and fit- but don;t work.

kevvvinoOo

Hey i have a c320 with the same problem your having, i've actually had my technician who i usually bring my cars to to have it checked out but it was there for over 3 weeks and he couldn't figure it out... I had my air pressure for emissions replaced, esp lateral sensor, and my ac compressor which he couldn't get any of them to function. I have all lights on as well (which started just with the ESP, and not sure about the abs) but the BAS is on as well. any luck with you?

MBtech1098

This means that there is a malfunction with ESP/BAS, it could be from a steering wheel not initialized, or any number of things. This would also include a malfunction with the left front wheel speed sensor L6/1.

Not necessarily.

As far as different types of sensors, I don't recall this nor do I see any supersessions in EPC. Not stating it is incorrect, do you have any additional info to substantiate this? Was it a supersession in Paragon? The only variations in wheel speed sensor I see are 203-540-12-17 for 4Matic, and 203-540-04-17 2WD. Both left and right are the same.

To the OP, some information you can use to assist in diagnosing the issue. You state they have replaced the ESP control unit and left front wheel speed sensor and this has not resolved the issue. Now the reluctor ring is a possibility but so are several other things still. We know most likely we can rule out the sensor and ESP control unit. We also know we can rule out any type of CAN error, if we had a CAN error there would be a lot more CAN faults displayed complaining about more than just the wheel speed sensor L6/1. What about the wiring from the sensor L6/1 connector X62/7 to ESP N47-5 pins 3&4? Several possible issue, some more likely than others; short to power, short to ground, wiring integrity, or cross continuity.

When testing wiring a lot of guys forget about shorts to power, ground, and cross continuity. Usually they will just test continuity from A to B and assume all is well, but we know this is often not the case. We also know that a short to power is highly unlikely in your situation, as this would most likely cause additional damage and faults to be reported by ESP.

We are now left with two possibillities, short to ground or cross continuity. If we unplug the wiring at both ends to isolate the circuit and check them to ground it should read OL or infinite on a DVOM, also if we test the one wire to the other we should get the same result.

Any deviation from those readings, and we have found the problem...wiring. It is also good practice to wiggle the wires and give a good visual inspection.

awiner

I am having this same issue on my 2003 CL55. This started after a front brake job (Rotors/Pads) and new front wheel bearings/seals.

I am going to install new front hub seals (which contain the ABC tone ring) this week and see if it cures the issue.

If not, electric hunting I go.

MBtech1098

What was the reason for replacing the wheel bearings? How many miles are on your CL.

In your case it sounds mechanical being as the issue has presented it self right after you had everything apart. If there is the slightest bend in the ring, it will set a code for the speed sensor.

In your case the issue could easily be determined with a oscilloscope. However you most likely don't have one readily available, so visual inspection it is.

awiner

102,000 miles on the CL55. While i was replacing the front rotors and pads I figured I might as well do the front bearings as well since I was 3/4 of the way disassembled.

I did NOT replace the hubs, however pressed the races out and pressed new ones in with new bearings and new seals/toner rings. My guess is that when putting the new seals/rings on I probably caused the issue as you surmised with a slight bend on the tone ring.....

I have two new hubs on order which as you know come complete and will swap those out when I receive them this week.

It was interesting to note that the stock drivers side race was starting to turn a shade of blue. Grease was still slime green. The passenger side grease however was dark and grimy looking.

Thanks for your advice and continued support on this forum. I will let you know what transpires after the replacement.

awiner

Update: Installed OE hubs which come with OE bearings and tone ring/seals.

All errors gone after install.

What I feel the difference was that caused the errors all has to do with the aftermarket bearings/races.

It appears that the inner race was 1 - 1.5mm less in height. This made the tone ring/seal sit flush with the end of the hub. The OE hub assembly has a 1mm gap between the end of the inner hub face and the tone ring/seal. This 1mm was enough to cause the front abs wheel sensors to not sense the tone ring correctly and within spec.