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Premium Member
'92 S Class
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154 Posts
Discussion Starter #1
Hi guys, I've done a LOT of research on this, and I now need some help.

ABS light comes on just after I start moving. It used to just come on sometimes, but now it's every time. I noticed that the times that it DOESN'T come on, the speedo displays a speed right from 0 when I start moving. The times that it does come on, the needle is showing 0 until I'm doing over 10 or so, and then it pops up into action. Recently it's been a higher and higher speed until about a week ago when it didn't even read at all while I was going to work. (Odometer didn't register even 1 mile the whole trip to work).
NOW, this is happening....check out the video please and give me some ideas. I've checked all speed sensor by spinning wheel and reading AC voltage on the terminals.


Thanks!
 

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1997 S500V, 1999 S500 grand edition, 2006 s65 amg
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7,356 Posts
i dont know if the w140's have it but this happens when the speedo cable is damaged but i dont know what caused your abs light
 

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Premium Member
'92 S Class
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154 Posts
Discussion Starter #3
I think what happens is the ABS sensors are telling the module that the wheels are spinning, but the computer isn't getting a speed input, and it's faulting out the ABS.
I'm hoping that someone is going to say that the speedo runs off of a different sensor that's mounted on the tranny or something like that....and maybe provide some info on where it's located, how to test it, and a part number....haha.
 

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1997 S500V, 1999 S500 grand edition, 2006 s65 amg
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7,356 Posts
well i wish you luck. i am off to the shop for my leak and while i am there i will ask.
 

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Banned
2008 C200K (W204) & 1998 SL500 (R129) Imperial Red
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3,373 Posts
My speedo also acts up sometimes.. While the vehicle is stationary, the speedometer goes all the way to the highest reading then it comes to back to normal. It happens so quick that you can miss it if you not looking at the clocks.. Thats why i havnt even bothered trying to sort that out. I just pray it doesnt get worse
 

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Premium Member
'92 S Class
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154 Posts
Discussion Starter #6
My speedo also acts up sometimes.. While the vehicle is stationary, the speedometer goes all the way to the highest reading then it comes to back to normal. It happens so quick that you can miss it if you not looking at the clocks.. Thats why i havnt even bothered trying to sort that out. I just pray it doesnt get worse
That's probably my problem then, I didn't pray, and it got worse. ;)
I've also noticed while on the highway, the tach and speedo will both drop to zero for about 2 seconds, and then come right back up to speed. It's only done that a hand full of times, and with no other side effects, I just ignored it.
 

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1997 S500V, 1999 S500 grand edition, 2006 s65 amg
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7,356 Posts
ok i got back from the shop(no leak to be found :( since its leaking bad) anyways they said its most likely speed sensor and they were pretty busy. he said does the traction triangle turn on randomly when driving. i think the ones on the w140 are at the wheels
 

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1997 S500V, 1999 S500 grand edition, 2006 s65 amg
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7,356 Posts
no problem. now i am just looking for that leak, once i got home it started again so i am off to the shop again. this time i will try and find out where is the sensor. btw he told me that if that thing was messed up it would set off the asr, bas since the car will think something is wrong he said you have to hook it up to star to be sure
 

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2008 C200K (W204) & 1998 SL500 (R129) Imperial Red
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3,373 Posts
That's probably my problem then, I didn't pray, and it got worse. ;)
I've also noticed while on the highway, the tach and speedo will both drop to zero for about 2 seconds, and then come right back up to speed. It's only done that a hand full of times, and with no other side effects, I just ignored it.
I pray it doesnt get worse lol.. got many other things to fix before I can even think of this..

Still need a PSE pump, rebuild my tranny (No reverse gear) upper wire harness and some other small things.

Money must be spent, but gotta priotise what gets repaired first
 

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1997 S500V, 1999 S500 grand edition, 2006 s65 amg
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7,356 Posts
do not get your pse pump rebuilt. they mess up and snap rods from my personal experience. hate mercedes transmissions they are bad quality. wire harness at dealers should be around 500 bucks. please dont dump your w140 for small issues lol
 

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Premium Member
'92 S Class
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154 Posts
Discussion Starter #12
Ok Ladies, please don't jack the thread....I'm trying to get the speedo/ABS issue resolved. Wiring harnesses and little shit like that is another deal.
Tranny issue, whatever....yank it out, rebuild it, or get it rebuilt. Come on now.
I'd MUCH rather deal with those issues! And if you think I'm joking, I'd do the jobs for each of those issues for you for free if you'll either figure out my issues, or pay to get it fixed for me.
 

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1997 S500V, 1999 S500 grand edition, 2006 s65 amg
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7,356 Posts
sorry about that we kind of got carried away. i talked to my mechanic again and he said did you change the rims or are they oem? also he said check the speed sensors but didnt say where it was or how. also does the cluster have issues? also the best thing is to hook it up to star and it should say whats defective if its a speed sensor. also there was a sensor in the tranny for speed
 

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1997 S500V, 1999 S500 grand edition, 2006 s65 amg
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but the best remedy is hooking it up to the star since there is about 4 sensors and from the past i read on the forums they cause abs light and speedo being off. star uncovers secret issues which is better to fix as soon as possible. before other stuff mess up. there is one speed sensor for each wheel plus i think there was one in the diff and tranny. which will be pricey to change all so just hook it up to star so you can uncover the mysteries

if your that generous come down to california rebuilt my transmission and the seals and i will fix those sensors. i am just kidding, but that did sound a bit rude. i am trying to help you but i kind of got carried away

start by checking with star diagnostics and it will say which one is defective. and those sensors arent that expensive or hard to change. just search w140 speed sensor on the forum and you will see the issues and causes and remedies.
 

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w140 s500 1994,w123 230c, w123 280ce etc
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is the cruise control affected at all.
IE.have you tried driving the car with the cruise on and does it switch itself of
???
 

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Premium Member
'92 S Class
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154 Posts
Discussion Starter #16
but the best remedy is hooking it up to the star since there is about 4 sensors and from the past i read on the forums they cause abs light and speedo being off. star uncovers secret issues which is better to fix as soon as possible. before other stuff mess up. there is one speed sensor for each wheel plus i think there was one in the diff and tranny. which will be pricey to change all so just hook it up to star so you can uncover the mysteries

if your that generous come down to california rebuilt my transmission and the seals and i will fix those sensors. i am just kidding, but that did sound a bit rude. i am trying to help you but i kind of got carried away

start by checking with star diagnostics and it will say which one is defective. and those sensors arent that expensive or hard to change. just search w140 speed sensor on the forum and you will see the issues and causes and remedies.
I'd love to come to Cali! Ya it was a bit rude, sorry.
Thanks for the opinions of my car...I think everyone's right about hooking it up to star, but I don't want to go to the stealership...they'll charge an arm and a leg for that. I'll check some smaller garages locally.

sorry about that we kind of got carried away. i talked to my mechanic again and he said did you change the rims or are they oem? also he said check the speed sensors but didnt say where it was or how. also does the cluster have issues? also the best thing is to hook it up to star and it should say whats defective if its a speed sensor. also there was a sensor in the tranny for speed
Rims are OEM, I checked the two front and one rear diff speed sensors, they are good. I only recently read that there might be a sensor on the tranny, and I'm in Atlanta right now for a trade show so I have a little bit of extra time on my hands, but I don't have the Benz handy to work on. I'll dog some more on the tranny speed sensor.
Thanks for your feedback!!

is the cruise control affected at all.
IE.have you tried driving the car with the cruise on and does it switch itself of
???
The only time I've ever had problems with the cruise was when the speedo was reading 0 while I was driving down the road around 35 Mi/Hr.
Thanks for your input!
 

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Premium Member
'92 S Class
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154 Posts
Discussion Starter #17
I just searched ALLDATADIY for Transmission Sensor and I did find something.



I'll have to do some more digging, but I believe this is the root of my issue.

Wheel Speed Sensor Values:
 

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Premium Member
'92 S Class
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154 Posts
Discussion Starter #18
From this document, it looks like the front left wheel speed sensor supplies the speedo. I'll have to test it again, and start by spinning the wheel slowly and see if there is a jump in the AC voltage (sine wave output):

 

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1997 S500V, 1999 S500 grand edition, 2006 s65 amg
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7,356 Posts
see if you was in cailfornia my cousin would have hooked it up to star for about 20-30 bucks.
 

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95 S500, 07 S550 AMG
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791 Posts
it seems like the speed sensor to me. Or a lose connection. Unplug ur battery first, let it sit for 15 min and plug it back in. See if this changes anything.

I have not checked on my car but usually the speed sensor is on one of the wheels and so is the ABS(usually on the wheel hub). I don't know what S class u have but you should have a triangle at your speedometer. I know you said you didn't but its hard to see unless TC engages and turns on.Double check, i thought all w140's had the triangle no matter if they came with TC or not.
 
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