My 1994 E320 wagon started to have abs and asr
warning lights on after I drove above 5 miles per
hour. When turn off the ignition and start again, the
abs and asr were off until driving again. I suspected
wheel speed sensors might be damaged or dirty but
don't know which one. So I used the 16 pin connector
next to the battery with the push button to read the
codes to pinpoint the problem and showed no
blinks/flashes, just the LED on (Igntion turn on, no
start). I also tried the code reader and had the same
results, LED on and no blinks/flashes. In addition, I
took out the brake light switch located behind the
brake pedal to test it using the multimeter and works
fine. All my brake lights in the rear of the wagon
works good.
In addition, I checked the OVP (Over Protection Relay
behind the battery under the cover) for damage fuse,
none of the fuse was broken, but I replace the fuse
just to be safe. The OVP was replaced last year when
I replaced the alternator as well. The battery and
alternator are fine.
I am tempted to go to the Mercedes dealership 80
miles from home to have the diagnostic scanner test
and the cost is around $160 for the test, taking a half
day worth of work, so the Mercedes dealership
claimed. I am not too crazy about doing that. I am
also tempted to look into buying an OBD I diagnostic
scanner tool, if there is one for my 1994 E320 w124 and I am not sure that would help either, since I
already have a code reader. Any ideas or
suggestions? Your response is greatly appreciated.

Unless you have complete faith that your current OVP is working properly, I'd get another new one and re-test. I just replaced an OVP that still had fuses intact, but did not function properly. I'd even get a cheap, but NEW one. Even if it turn out not to be the culprit, it's good to have a spare OVP in the "anti-strand emergency parts kit" for the trunk.

__________________
03 CLK430 Cabrio 211K Pweter Silver/ Oyster Leather
90 300SEL 214k Pearl Black/ Alto Grey/Black Leather

Prior: 85 190E, 88 300TE, 89 300TE, 90 300E 2.6, 90 300TE, 92 300E 2.6, 91 and 93 300SL, 87 Ferrari Mondial Cabrio

Thanks for the tip on the OVP relay. I am still trying to narrow down the process of elimination in regards to the ABS/ASR issue. So far, I am checking the ABS relay sensor located in the ECM. Will follow up on this and other possibilities and get back to you all and report of my findings. I will keep you guys posted.

So far, I checked the wiring harness and it is good. So are the fuse number 9 and the 12 voltage in pin 16 also. Need to investigate further due to process of elimination. Switch to older OVP is my next step as well as the abs relay located in the ECM

Also I checked the abs wheel sensor. Problem is one of the bolts to disconnect the wheel speed sensor is stripped. However, I was able to remove the other wheel speed sensor and it looks dirty. I cleaned up the wheel speed sensor, reinstalled the sensor and still come up ABS/ASR lights on. More later..

Just got back from a reputable mechanic who did the diagnostic work on my 1994 Mercedes E320 wagon. It was found that the ABS/asr wheel speed sensor need to be replace on the LEFT Rear of the wagon. My question is since I did not know whether the replacement wheel speed sensor is with traction or without traction. I do have a triangle yellow light hazard shown in the in the upper middle of the speedometer. Does that mean I have traction and if so do I need to replace the wheel speed sensor with traction? Any response or comments is greatly appreciated.

"ASR" is traction control.

__________________

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3" Exh, AEM W/B O2
Underdrive Alt. and P/S Pulleys,
Vented Rear Discs, .034 Booster.
3.07 diffs 1st Gear Start

90 300CE 104.980
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V8 rear subframe, Quaife ATB 3.06 diff

Im pretty sure it could be a fault with the tone ring on the rear axle, just as likely as a fault in the sensor itself, and you'd get the same fault on the scanner.

Unless he tested the actual sensor with a voltmeter, it would be hard to know which problem it is

Thanks to all who respond. I am about to jack up both rear tires tomorrow to find the rear wheel driver's side near the differential axle in the middle. My goal is to find the end of the connector so I can test the resistance of the wheel speed sensor. Some say the end point of the connector is located under the backseat. Remember, I have a 1994 E320 wagon. I tried to locate the end connector in the back seat and does not show up there. Some also said it could be located behind the cover on the right side near the tail light with all those wires there. Again, I tried to locate the end connector but nothing there. Any suggestions, feedback, or ideas. My best bet at this time is to jack up the rear tires and follow the wheel speed sensor cable to its supposedly location. Will follow up on this issue. Once I am able to locate the end connector cable, I will test the resistance to make sure it is in good working order. If not, I will remove ABS wheel speed sensor carefully not to strip the removing bolt as it happened on the front passenger side. Once I remove the sensor and looking for magnetic particles or dust or dirt, clean it up and test for resistance again. If there is still no resistance, then I have to buy a new one and is very expensive. I am hoping the issue is cleaning up or looking for cracks in the cable, etc. so I won't need to buy a new one.

Suggest you crawl underneath and look at the hub where the axle fits into it...if you can see any of the reluctor ring, then it may have cracked and wiggled out of position. I just had this happen on my c280...BOTH rings had cracked and become loose enough to move inward on the axle shaft end to make the ABS sensor warning go off.

My guy said the rings arent the root problem, it's the axle that gets rusty and it expands enough the crack the ring, which on my car are stainless steel, and were in surprisingly good shape, even at 17 yrs old. So all they did was clean everything up, corrosion-wise, painted the axles in zinc paint and welded the rings back in place

Alternative was new axles, and ummm at 1300/pce...not gonna happen

Thanks for the last message above. I finally located the ABS rear wheel speed sensor on my 1994 E320 wagon. As far as I can tell, it is the only one rear speed sensor, not two as some reported to say have that. By definition, the ABS wheel speed sensor is LEFT side of the driver side, when in fact, I noticed the wheel speed sensor is only one and in the middle. Confusing, huh?The ABS rear wheel speed sensor is located on above the differential axe in the middle on top. Just barely enough room to feel the sensor and not enough room to see and to remove the bolt from the sensor, since I am under the ground on my back looking up with limited view of the sensor using the two ramps to lift the back end. I wiggled the sensor as to see and feel it is loose. It is not loose. However, I did see a line cable from the sensor going through the underbody of the wagon. However, I cannot find the end point of the cable so I can unhook it to measure the resistance without taking the ABS wheel speed sensor off from the differential axle. Some people say the end of the cable is located under the back seat. So I removed the back seat and no end cable is found. Some people also said the end cable is in the rear compartment. Where is the rear compartment is located? Is it behind the cover on the right side near the rear passenger tail light where the jack is stored? I don't think so, due the line of the cable is going forward under the body toward the right passenger side past the backseat.

I am tempted to take the wagon to the shop for the mechanic to remove the sensor and replace a new one, because I am afraid that I will stripped the bolt with limited play and cannot see to remove the bolt from the sensor from under the ground. The total cost will be around $380 including labor and a new ABS Wheel Speed sensor part. Any suggestions or ideas is greatly appreciated.

On older w202's with the rear speed sensor in the diff, that wire passes up through the spare wheel well and then to a connector in there somewhere. Maybe yours does that?

Rear Speed Sensor replacement - DIY - Mercedes-Benz Forum

I hope that is your problem. I had a '94 CE320 with the exact same symptoms (ASR light on, pull over, restart engine, never occurring again that day). We fought it for 3 years and NEVER found the source. Even replaced the ETA but no change. Finally sold the car.
Good luck!
Anziani

I finally located the rear speed sensor end connector. There is a black plastic cover under the wagon near the rear right passenger door. Three 10 mm bolts removed. Under the plastic cover, there is a circular black knob that turns counterclockwise and pull down to see four set of wires with label part numbers end connectors:

A: 124 543 57 26 L A Top

A:124 543 58 26 R A Bottom Broken wire. Strip the wire on both ends and used blue connectors (14-16 gauge). After finishing connecting the broken wires (2 separate wires) with 2 blue connectors, I noticed the Diagnostic Self Test working again and the Transmission fluid meter in the instrument cluster panel works as well. This particular wire is the electrical cable according to the google search. This is only a temporary
fix until I get the correct part number to replace it. Also, where does this particular wire goes to besides the other end?

D:124 540 22 17 R Wheel Speed Sensor

E:124 540 21 17 L Wheel Speed Sensor

Since I was abled to find the wheel speed sensor on the left differential, I was surprised that there is a right Speed Sensor that I was unable to locate it at this time.

I tried to measured the resistance on both wheel speed sensors:124 540 22 17 R Wheel Speed Sensor and E:124 540 21 17 L Wheel Speed Sensor and because of the tight space and restricted movement under the wagon, I was unabled to get an accurate resistance. What ohms dial should I use to get an accurate measure of resistance?

I did a test drive after repairing the broken electrical cable and the ABS/ASR warning lights still showed up. At least I am on the right path to resolve the ABS/ASR issue.

Also when using the self-diagnostic test module (16 pin square box near the battery), it shows diagostic code flashes 4 and 5. However, using the three banana plugs code reader did not show anything.

Code 4 flashes is Air injection system faulty hot film mass air flow sensor with hot wire.

Code 5 flashes is Exhaust gas recirculation faulty.

Next step is to remove the stripped bolt on the right passenger side and clean the wheel speed sensor as advised earlier in the above comments section.

Also, to resolve code 4 flashes and code 5 flashes as mentioned above.

Any comments/feedback? Thanks to all who have been reading and
writing comments.

While researching for the 4 wirings on the web, I found this exactly the same thing including the wire part numbers. Just to give the idea of what I was talking about. Click on the item below and will show the pictures as well.

https://www.benzbonz.biz/store/index.php?main_page=product_info&cPath=35&products_id=1576