ASR light on (triangle) but no ABS light on while setting off - SOLVED

[Rycy85]

Moderator edit: Root cause was a defective ASR module, see post #36 below.

Hi All
I try to summarize my story. During MOT it was found that my 500E from 1991 has no ABS. So I started the investigation. After reading through most of the threads here re ABS/ASR the current situation is as follows:

*Problem*:
Ignition on, ABS light on, ASR light on, ASR triangle light on. Engine start, all lights off. So far so good. Setting off and the limp mode kicks in with ASR triangle light on, but no ABS light nor ASR light on.

*Investigation and checks so far*:
- checked fuses - all good
- checked relays next to the ABS/ASR pump - seem to be OK
- grundmodul - I found out that there were 3 10A fuses. Ordered more so tomorrow I do the test with 4 fuses. I replaced the 3 I had, so somebody has taken out the fuse for ASR (before there was never triangle light or ASR light on).

Tomorrow I will try again with all 4 fuses (but I doubt it would magically help solving the problem). My next suspects are ABS/speed sensors which I will have to check.
If needed, I may buy the simple code reader (the one with light). I wonder if getting a different set of ABS/ASR relays would be needed.


Any other idea what that might be?

Thanks in advance.
Cheers,
M.

 

[gerryvz]

You really need to scan and pull codes, and then erase the codes, drive the car, and then see what codes come back. That should point you in the right direction as to what is wrong. DO NOT replace any parts, modules or relays UNTIL you do this, as a starting point.

 

[gsxr]

What Gerry said. Need to clear all codes, then start/drive the car and see which fault codes return immediately, particularly on pin #6 (ABS/ASR).

The ABS/ASR module is split into 2 halves, one for each function. They operate separately, and if power is not provided to one it won't work (while the other may be fine). Start with the fuses first of course, on the BM/GM.

Read this thread for info on pulling blink codes, use the PDF file attached in post #1 for decoding the blinks.

 

[Rycy85]

Thanks for the answer. The simply code scanner is ordered

I did some further investigation today (to eliminate next items). So in the nutshell...

Update:
- 4th 10A fuse mounted - no change. ASR and limp mode on when I start driving

Then I decided to play with 2 relays in the hydraulic block:
- 0332002171 (the one with 4 pins) removed - car drives normal, no ASR but no ABS
- 0332002173 (the one with 6 or 7 pins) removed - ASR light on, limp mode on while driving. No chance to test ABS.
- both removed - car drives as before, no ASR, but no ABS
This shows that the 0332002171 with 4 pins may be broken, as putting it on or out makes no change in car behavior.

Next I did:
- FR wheel speed sensor looks clean - it was cleaned during last service 2-3 months ago when MB checkd the break pads on this side
- FL wheel speed sensor looks a bit more dirty, but not crazy

Plan for tomorrow/weekend before I get the scanner:
- clean FL wheel speed sensor
- clear rear speed sensor
(test drive); I may get the tool and check the Ohm on each of the sensors, too)

I hope this sheds some light on the topic and potentially eliminates other suspects.

 

[chicky]

Hello Rycy85

... if after cleaning the FR and FL speed sensors and find nothing wrong with them ... I can make suggestions as to what to check next as I had the ASR triangle light "on" but no ABS/ASR light "on" for my '91 R129066.

 

[Rycy85]

Hello Rycy85

... if after cleaning the FR and FL speed sensors and find nothing wrong with them ... I can make suggestions as to what to check next as I had the ASR triangle light "on" but no ABS/ASR light "on" for my '91 R129066.

I'd love to hear your journey and to see the list of items that you've checked to solve the problem in your R129. btw. what was broken and how did you solve the problem?

Thanks in advance.

 

[Rycy85]

More checks done today:
- front sensors cleaned (at least some positive news)
- rear sensor - I couldn't get it out of differential. It's located on the left side, yes, but more like from the top of the differential, so there's not enough space between floor and differential case to take out the sensor. How did you do it guys?


Resistance measurements:
FL - 950 Ohm
FR - 1350 Ohm
Rear - 1350 Ohm

I found out that the cable of the rear sensor goes into the cabin under right rear passenger seat. What's quite surprising is that from the underbody there are 4 cables, that go into 3 connectors inside the car. Is this normal? Do our 500E cars have only 1 or 2 ABS sensors in the back?

 

[gsxr]

There is no need to remove the rear wheel speed sensors from the differential. If the resistance is normal, they should be fine. A 500E with ASR will have two sensors, one on each side of the diff, one for each rear wheel/axle.

The 3rd and 4th wires are for the brake pad wear sensors. In the large round connector positions D, E are for the wheel speed sensors and F, G are for the brake pad sensors.

 

[Rycy85]

@gsxr
thanks for quick response.

Then I confirm that both positions D and E have ca. 1350 Ohm resistance.

so the question is if the FL with 950 Ohm is normal and OK as this is the only one with lower resistance.

 

[Rycy85]

One more test and all 4 showed me some voltage while turning wheels.

What interesting this time no ASR light on, no limp mode. But unfortunately also no ABS

Any ideas?

Ps. Next week I receive the code scanner and will read the errors.

 

[Efraim]

*Problem*:
Ignition on, ABS light on, ASR light on, ASR triangle light on. Engine start, all lights off. So far so good. Setting off and the limp mode kicks in with ASR triangle light on, but no ABS light nor ASR light on.

Your case is really interesting because such fault is not listed in Star diagnose manual. Sorry, I can't advice you any more than guys before but I'm interested and will follow the situation.

Do you have available relevant docs related: Wiring diagram, Functional description, Diagnose manual?

 

[chicky]

I'd love to hear your journey and to see the list of items that you've checked to solve the problem in your R129. btw. what was broken and how did you solve the problem?

Thanks in advance.

Hello again Rycy85

Solving the ASR triangle light problem required a lot of patience and time on my part. I did a lot of research first as to what possible sources of the problem by using the MB WIS which I luckily had printed out ... then decided to go thru each and every one of the listed possible sources of the problem. I am a favorite client of MBCC LB as I listed all the possible parts that I would need and if NLA search the parts from other sources. My point was that since I will be checking, removing old parts I might as well change the normal wear and tear and other critical parts since the car at that time was already 33 years old. Also I did not want to be servicing the system only to find out that I need to change something and being in Asia, it takes more than a month for parts to arrive from either the USA or Germany.

Just to give you an idea of the scope of work, I have a folder specifically on my ASR-ABS fault as shown on the attached picture of what that folder contains

The WIS listed the checking of the rear speed sensors as #1, so I followed ... please see attached pictures

... more later on as I do not want to hijack your thread

 

[Rycy85]

I’ve already did the sensors check. Front right has lower resistance comparing to others but all of them give some voltage while I turned the wheels.

As mentioned above I did another test today and car was driving normally, but still no ABS.

I A know that im quite patient person but I have a hard stop in 2 weeks when I have another MOT

 

[Rycy85]

Your case is really interesting because such fault is not listed in Star diagnose manual. Sorry, I can't advice you any more than guys before but I'm interested and will follow the situation.

Do you have available relevant docs related: Wiring diagram, Functional description, Diagnose manual?

I think I have most of them but maybe you could attach them in this thread. Thanks in advance

 

[gsxr]

Resistance measurements:
FL - 950 Ohm
FR - 1350 Ohm

Checked a couple of my cars. THe front sensors measure right at 1000 ohms. Your right side at 1350 is a bit high, but the output is a voltage waveform, and the resistance may be irrelevant.

 

[gsxr]

I think I have most of them but maybe you could attach them in this thread. Thanks in advance

Links to the factory Diagnostic Manuals are in this thread. The site is not easy to navigate or understand, but all the information you need is there. I think this section may have most of the ASR diagnostics.

 

[Efraim]

Functional description:
https://www.w124performance.com/service/w124CD2/Program/Chassis/42-0800.pdf

Wiring diagram:
https://www.w124performance.com/service/w124CD1/Program/ETM/2442300.pdf

PS:
Every time I read these documents I am so grateful to whoever shares them. Hobby with .36 would be painful without this material.

 

[Rycy85]

thanks a lot!

I had some time today and checked pins in the connection box after removing ASR control module.

Generally speaking the FR sensor looks a bit odd (pins 2.13 & 2.34 from https://w124performance.com/docs/mb/W124/ASR_pinouts_124_129_140.pdf) - 1500 Ohm resistance, but it show some voltage while turning wheel.

Another thing that might be odd are insulation resistance tests from above mentioned pinouts document) - according to the documentation they should be above 20k Ohm, but in my case all showed open circuit. Test steps: 14.1, 16.1, 18.1 and 20.1)

Does anybody remember what was the measurement is his car?

I test drove the car today (just few meters) and the limp mode + ASR triangle light went on almost immediately while rolling. I purposely disconnected one of the sensors and it behaved same way. I tend to say, that the FR sensor is the cause here... Can anybody from his experience confirm(deny this suspect?

Also... what's the behavior is your cars? if one of the ABS sensors is disconnected - does it switch on any of the lights on the instrument cluster or only the ASR triangle?

Thanks in advance.

 

[Rycy85]

and one more thing to make it clear. I said earlier "limp mode", but to be clear. When I set off and car starts moving forwards, I get almost instantly a triangle light on and the car feels like it applies ASR - sort of "pulsating" deceleration with a bit of breaking, no reaction/very slow reaction from the acceleration pedal input. while this happens, there's no ABS nor ASR light on.

 

[gsxr]

Also... what's the behavior is your cars? if one of the ABS sensors is disconnected - does it switch on any of the lights on the instrument cluster or only the ASR triangle?

I disconnect the front right wheel speed sensor at the dragstrip to disable ASR (and ABS). The ABS+ASR warning lights in the cluster turn on, but the triangle in the speedometer remains off. The lights go off when the sensor is reconnected, and a fault code is stored on diagnostic connector pin 6 (ABS/ASR module).

and one more thing to make it clear. I said earlier "limp mode", but to be clear. When I set off and car starts moving forwards, I get almost instantly a triangle light on and the car feels like it applies ASR - sort of "pulsating" deceleration with a bit of breaking, no reaction/very slow reaction from the acceleration pedal input. while this happens, there's no ABS nor ASR light on.

If the first 1/2 of accelerator pedal travel does absolutely nothing, that is definitely limp mode.

You must get fault codes from the ABS/ASR module, and E-GAS module, to determine what the computers are unhappy about. As an FYI, you will always get phantom code #30 on ABS/ASR when limp mode occurs - just ignore code #30.

 

[Rycy85]

You must get fault codes from the ABS/ASR module, and E-GAS module, to determine what the computers are unhappy about.

You've just reminded me something. I tried it once, but as I don't use it often I forgot. The cruise control in the car doesn't work. No warning light, nothing. simply no action while playing with lever. This may point me to the direction of E-GAS module.

waiting for the code scanner to investigate further...

 

[gsxr]

You've just reminded me something. I tried it once, but as I don't use it often I forgot. The cruise control in the car doesn't work. No warning light, nothing. simply no action while playing with lever. This may point me to the direction of E-GAS module.

waiting for the code scanner to investigate further...

Check the E-GAS module part number... and the ASR module part number as well. Remove the CAN box cover and snap a photo.

Also - when limp mode is engaged cruise control will not work.

 

[Rycy85]

the cruise control didn't work before; when the car operated "normally" with one missing 10A fuse in ASR module. For sure somebody must have done something in the past and most likely failed or it was too expensive to fix it.

When I mounted the 10A fuse, the limp mode kicks in immediately which I'm still trying to solve.

E-GAS: VDO - 421.255/001/017 MB - 124 545 26 32
ASR: Bosch - 0265 106 034 MB - 010 545 99 32

photo attached (ASR module removed for testing pins)

 

[gsxr]

Looks like all your modules are correct for the car, so that's a good sign.

Back to needing fault codes!

 

[Rycy85]

Looks like all your modules are correct for the car, so that's a good sign.

Back to needing fault codes!

I seriously look forward to it

ps. I unplugged all modules and plugged them again, replaced the W1.2W bulbs in the instrument cluster and now I have constant ASR light on. After starting the engine ABS and triangle go off, but ASR stays on. So even though the problem is not solved, I think this is a right step forward as it's less of a mistery now

 

[Rycy85]

Another idea/another check. After removing and plugging again all the modules, I'm back to base 1 - ASR light goes off after engine start, but when I set off triangle light is on, no ASR light and limp mode.

I see that somebody must have done something with the Grundmodule. Please see the pictures below.

Can anybody confirm the right part number for my W124 500E for the Grundmodul?

 

[gsxr]

BM/GM module looks original / correct. You could try another one if you want. There are a couple of newer part numbers that are interchangeable.

 

[Rycy85]

Hi guys,
so I got the code scanner.

There were some errors on pins 6, 7 and 8. Deleted all of them, made a short drive - again from ca 5kmh triangle warning light on and car behaved like with the traction control/ASR on. Came back, tested again and... zero, literally zero errors on pins 6,7 and 8.

I tried something else - wanted to try what @gsxr did - unplugged one of the speed sensors, but in my case - no warning light at all.

My conclusion may be wrong, but for me it looks like the ASR module is broken. It ignores any of the inputs and kicks the ASR on, when the car is moving. When the fuse was removed or when I didn't plugged it hard enough, then the ASR warning was on all the time, but no ASR/ABS.

it seems that somebody tried to repair it before but knowing how much it costs to get the new ASR module he simply removed the fuse and the bulb in the cluster (extremely unprofessional, but we know it happens).

I think of buying a used but working ASR module and verify if I'm right.
What are your thoughts?

 

[gsxr]

I agree... I'd try a different ASR module. Just make sure it's the correct part number for the "early" 500E (up to about March 1993 production). Look for 013-545-36-32 in addition to the part number in your car now. The same ASR module is shared with the 400E/420 and some R129 as well.

Later E500 ASR module 014-545-01-32 is NOT compatible with your 1991 car.

 

[Rycy85]

mine is 010 545 99 32 - which seems to be yet another number?

 

[gsxr]

mine is 010 545 99 32 - which seems to be yet another number?

That was the original when the car was built. It apparently was superceded to 013-545-36-32 later on, which is backwards compatible.

Any chance you know someone with a car that has the correct ASR module, that you could swap for testing?

 

[Rycy85]

Thanks for clarification. there are few of them on eBay which should be relatively easy to get (but not cheap).

I thought about it, but unfortunately I don't have anybody here locally. I will try to get a used module (fortunately they accept returns) and get it shipped asap.

I hope this solves the mistery in my car...

 

[Rycy85]

That was the original when the car was built. It apparently was superceded to 013-545-36-32 later on, which is backwards compatible.

Any chance you know someone with a car that has the correct ASR module, that you could swap for testing?

Do you know if 013 545 35 32 is also compatible with my 500E 1991?

 

[gsxr]

Do you know if 013 545 35 32 is also compatible with my 500E 1991?

I do not know. That part number only shows as being used in the 140 chassis. Might work, might not...

 

[Rycy85]

@gsxr
you are a serious guru here thanks a lot for the support. I ordered last night a 010 545 99 32 module and should be here tomorrow/Monday. I'm very curious if this fixes the problem

 

[Rycy85]

All,
just for future reference- the issue is solved. The ABS/ASR modul was broken. After replacing it with the "new" one, all works good and there's no limp mode.

ASR works and expected and kicks in when I try donuts and ABS works, too.

Thanks a lot for all the support!