W124
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2014 G550, 2000 SL500, 1995 E320 Cabriolet, 1980 TR8
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I am the first to admit that, unless it is a W463, I am not an experienced 4-matic person, but I'm going to approach it from the perspective of the ABS system and ask the obvious, and probably dumb question - are you sure that all four of your tires are the same outside diameter (size, wear, roundness, and inflation)? If you rotate the tires rear to front, does that change things?
Also, are your front bearings in good nick and properly adjusted? Play in the front bearings can cause noise in the magnetic signal fed to the ABS controller, which, in spite of input filtering within the ABS control, could be interpreted as a differential wheel speed. The higher the speed of the vehicle, the higher the noise content and hence the higher the possibility of an erroneous signal.
Just a few thoughts . . .
Also, are your front bearings in good nick and properly adjusted? Play in the front bearings can cause noise in the magnetic signal fed to the ABS controller, which, in spite of input filtering within the ABS control, could be interpreted as a differential wheel speed. The higher the speed of the vehicle, the higher the noise content and hence the higher the possibility of an erroneous signal.
Just a few thoughts . . .
Real1Shepherd is out resident 4-Matic whisperer. I am sure he will see this post soon and post up some additional things to think about.
@Floobydust
The tyres are all the same size and are in good condition. I wish it were a case of bad tyres!
Your point about wheel bearings is interesting. I’m not sure if their condition or adjustment. Could you explain a bit more about that?
@tuttebenne I am hoping that @Real1shepherd can help me, as he has so many others!
Thanks for your replies.
The tyres are all the same size and are in good condition. I wish it were a case of bad tyres!
Your point about wheel bearings is interesting. I’m not sure if their condition or adjustment. Could you explain a bit more about that?
@tuttebenne I am hoping that @Real1shepherd can help me, as he has so many others!
Thanks for your replies.
'92 300TE 4matic 280,000miles, '92 300TE 4Matic 'Ice Blue Metalic' 101,000miles
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Have you made the 4Matic brain itself render codes? It's a light blink process that uses your 4Matic trouble light....it's not the same as reading general codes with a handheld light blinker. Not going to be the wheel bearings....I've had them bad and no 4Matic system malfunction. They are sealed bearings and a BEAR to replace either with a special, expensive tool or removing the wheel hub and using a 50 ton press. If you put ea wheel up in the air and push/pull the wheel gripping the sides of the tire violently, all the way around 360 degrees and have no play, you're fine.
The 4Matics have their own brake light switch as well. Swapping out the steering wheel won't work if you have a bad steering wheel angle sensor....you have to replace the sensor. But we're getting ahead of ourselves....you need the 4Matic brain to self-diagnose the system.
We had this same problem before with the trouble light illuminating only at hwy speeds. Turned out to be a bad ABS unit.....was a member form Canada. We tried everything else before that.
PM me with your email and I'll send you the bleeding method and how to get 4Matic codes. My PC was confiscated, but I think I can find a member I sent an email to and rob the attachment out of that.
*Edit.....I did indeed snag the pdf from emails I sent to various members.....so PM your email address.
Kevin
The 4Matics have their own brake light switch as well. Swapping out the steering wheel won't work if you have a bad steering wheel angle sensor....you have to replace the sensor. But we're getting ahead of ourselves....you need the 4Matic brain to self-diagnose the system.
We had this same problem before with the trouble light illuminating only at hwy speeds. Turned out to be a bad ABS unit.....was a member form Canada. We tried everything else before that.
PM me with your email and I'll send you the bleeding method and how to get 4Matic codes. My PC was confiscated, but I think I can find a member I sent an email to and rob the attachment out of that.
*Edit.....I did indeed snag the pdf from emails I sent to various members.....so PM your email address.
Kevin
2014 G550, 2000 SL500, 1995 E320 Cabriolet, 1980 TR8
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1,979 Posts
If there is too much play in the wheel bearings the distance between the reluctor (the splines on the hub) and the ABS sensor can change as the wheel rotates, hits bumps, etc. The change in distance will change the voltage of the ABS signal which can produce a secondary signal which gets injected into the signal stream from the wheel sensors. If it gets too bad, the extra signal could, in theory, confuse, the 4-matic controller which derives its data from the ABS sensors.
I haven't done it on a 4-matic, but checking the bearing preload/free play should be fairly easy.
'92 300TE 4matic 280,000miles, '92 300TE 4Matic 'Ice Blue Metalic' 101,000miles
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Never seen this as a problem before, Flooby.....in a 4Matic system, even with a bad wheel bearing.....and I've had a few bad wheel bearings over the yrs.
I told him how to check for bad wheel bearings with the 360 degrees test, so as not to confuse with other issues like a bad tie rod or lower ball joint.
Rust can be a real deal breaker on the stator teeth of the front axles and the ABS sensor. Rust there can be a geographical problem like in the Salt Belt.
Kevin
I told him how to check for bad wheel bearings with the 360 degrees test, so as not to confuse with other issues like a bad tie rod or lower ball joint.
Rust can be a real deal breaker on the stator teeth of the front axles and the ABS sensor. Rust there can be a geographical problem like in the Salt Belt.
Kevin
2014 G550, 2000 SL500, 1995 E320 Cabriolet, 1980 TR8
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1,979 Posts
I've seen it come up in other threads about intermittent ABS lights. Wheel bearing adjustment to correct sensor output issues is also mentioned in the ABS troubleshooting documentation. I was reasoning that since the two systems rely on the same sensors, wheel bearing adjustment could also affect the 4-matic system.
'92 300TE 4matic 280,000miles, '92 300TE 4Matic 'Ice Blue Metalic' 101,000miles
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11,486 Posts
It's a good point, but I've never seen it as a problem with regard to the 4Matic system. And I don't want to send him down a rabbit hole when he has so much other stuff to check first for the trouble light coming on.
No wheel bearing adjustment in 4Matics....it's a sealed roller bearing that's preloaded with a wheel locking nut to about 210lb/ft. They have to be pressed out to repair and replace.
Kevin
No wheel bearing adjustment in 4Matics....it's a sealed roller bearing that's preloaded with a wheel locking nut to about 210lb/ft. They have to be pressed out to repair and replace.
Kevin
2014 G550, 2000 SL500, 1995 E320 Cabriolet, 1980 TR8
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1,979 Posts
Yes, with a bearing design like that I can see why it is unlikely to come up as an issue on a 4Matic.
VierMatic,
attached is a PDF I scanned a few pages from a book I got years ago. It's a 235 page, 1990 4Matic Preliminary book, filled with info, although it may give you some insight. I got the book in 1996 from a MB tech friend, at the time was a 40 year master technician. He had hundreds of these books, I saw it one day in his manual collection and asked if I could have it, which of course he gave me, knowing I had a strong interest in 4Matics. Maybe the info will help. Please keep us updated, and good luck.
Thorgod
attached is a PDF I scanned a few pages from a book I got years ago. It's a 235 page, 1990 4Matic Preliminary book, filled with info, although it may give you some insight. I got the book in 1996 from a MB tech friend, at the time was a 40 year master technician. He had hundreds of these books, I saw it one day in his manual collection and asked if I could have it, which of course he gave me, knowing I had a strong interest in 4Matics. Maybe the info will help. Please keep us updated, and good luck.
Thorgod
I have conducted a code scan using the OBD port which shows no errors. I did not realise there was another way of reading error codes? I am following the procedure in the 4MATIC workshop manual which I have. I know that the error system is working correctly as I forgot to re-connect one of the speed sensors and it flashed the relevant code.
I reasoned that the brake light switch is working correctly as when I touch the brakes the 4MATIC function indicator goes dark.
I have swapped the ABS unit for a spare one I have and this made no difference. I have also swapped out the 4MATIC unit and this too made no difference.
That would be appreciated. I will PM you now.
Hello Thorgod,
Thank you for posting that PDF. Luckily, I already have the book but your post will no doubt help others who stumble across this thread - so thank you.
'92 300TE 4matic 280,000miles, '92 300TE 4Matic 'Ice Blue Metalic' 101,000miles
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11,486 Posts
There is a difference in the way pre '92 4Matics bleed versus the prior yrs. The hydraulic control valve is different too, i.e., you can't put a '91 hydraulic control valve into a '92/'93 car without modification.
You force the 4Matic warning light to be your code blink light. I don't know what "book" you are using. The FSM stuff you may have assumes you have all their diagnostic tools. If you're going by factory stuff, you need the updated WIS for the yr of your car. One size does not fit all.
Kevin
You force the 4Matic warning light to be your code blink light. I don't know what "book" you are using. The FSM stuff you may have assumes you have all their diagnostic tools. If you're going by factory stuff, you need the updated WIS for the yr of your car. One size does not fit all.
Kevin
@Real1shepherd I have the 1990 Preliminary Workshop Manual that Thorgod kindly posted some pages of.
I have heard that there is a way to force the codes to flash up on the instrument cluster, but surely this is just the same as using a blinker test with the OBD? Or am I misunderstanding?
On another note, the 4MATIC system kicks in when it senses speed differences between the front and rear wheels. Could it be that my rear axle speed sensor isn’t performing correctly at highway speeds?
Thanks for all your help so far.
I have heard that there is a way to force the codes to flash up on the instrument cluster, but surely this is just the same as using a blinker test with the OBD? Or am I misunderstanding?
On another note, the 4MATIC system kicks in when it senses speed differences between the front and rear wheels. Could it be that my rear axle speed sensor isn’t performing correctly at highway speeds?
Thanks for all your help so far.
'92 300TE 4matic 280,000miles, '92 300TE 4Matic 'Ice Blue Metalic' 101,000miles
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11,486 Posts
You have to force the 4matic codes from the small test port by the battery.....it's specifically for the 4matic and forces the dash 4Matic trouble light to be your code blinker. It really does work most of the time.
If you had a bad rear axle sensor, the 4Matic diagnostic code for that would come up.
Use the instructions I emailed you and report back.
Kevin
If you had a bad rear axle sensor, the 4Matic diagnostic code for that would come up.
Use the instructions I emailed you and report back.
Kevin
2014 G550, 2000 SL500, 1995 E320 Cabriolet, 1980 TR8
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1,979 Posts
I haven't really thought much about the 4Matic system (since I don't have a W124 with it), but out of curiosity, I took a quick look that the ETM while I was waiting for my pizza to bake (and having a cold one), and I noted that the return circuit for the 4Matic trouble light (1Ae24) is also connected to pin 5 of the X11 diagnostic connector. So by momentarily grounding pin 5, in theory, it should be possible to read the flash flash codes on the warning light in the instrument panel (very convenient!). Does initiating a code read out via the 4Matic connector by the battery (which isn't even shown in the ETM) elucidate different or more detailed codes? That would be huge! There seems to be a great deal about the W124 4Matic systems that doesn't seem to be well documented (unlike most things regarding the W124). It's great that some helpful people have figured out a deep understanding of the 4Matic system.
Edit: Had another cold one and thought about it a little more, and in the case that the trouble light is already on due to a failure, there would need to be a secondary means of triggering the code read out since the controller would already have pin 5 at ground potential to keep the trouble light lit. Perhaps that is one of the purposes of the 4Matic connector by the battery?
Edit: Had another cold one and thought about it a little more, and in the case that the trouble light is already on due to a failure, there would need to be a secondary means of triggering the code read out since the controller would already have pin 5 at ground potential to keep the trouble light lit. Perhaps that is one of the purposes of the 4Matic connector by the battery?
'92 300TE 4matic 280,000miles, '92 300TE 4Matic 'Ice Blue Metalic' 101,000miles
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11,486 Posts
Flooby,
On the test connector X92(by the battery), you short out Pins#1& #5 momentarily to get the 4Matic codes to blink on the dash trouble light. Shorting them out for more than two seconds erases previous codes.
Kevin
On the test connector X92(by the battery), you short out Pins#1& #5 momentarily to get the 4Matic codes to blink on the dash trouble light. Shorting them out for more than two seconds erases previous codes.
Kevin
This is what I did, but using an external blinker rather than the light on the instrument cluster.
Also, so that others do not get confused - on RHD cars the test connector is by the fuse box, not the battery.
80 280SL, 85 300SD, 87 300TD, 90 300TE 4Matic, 90 300D 2.5 Turbo, 92 300D 2.5 Turbo, 92 300TE 4Mat
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The only 4Matic ABS computer unit is part number 005-545-52-32, NOT 005-545-21-32, 005-545-51-32, or 003-545-74-32.
I have seen 2Matic ABS units in 4Matic cars in pick & pulls and I suspect the 4Matic didn't function properly and that could have contributed to the decision to scrap the car altogether.
I have seen 2Matic ABS units in 4Matic cars in pick & pulls and I suspect the 4Matic didn't function properly and that could have contributed to the decision to scrap the car altogether.
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