ASR light comes, no ABS light or other symptom

[Lavaone]

I write that title reluctantly, afraid of fate.

94 E500 with ASR (obviously.)

Reset pins 6 and 7. Drove a 15 hihjwsy miles, ASR lit after a few minutes.

Stopped for gas.

Drove home 1/2 mile under 30 mph, ASR stayed off. About a 3 minute ride.

Pulled code:

Pin 6 = 21
Pin 7 = 6

Seems a bit different from other symptoms found in the Forum so any advice gratefully appreciated.

 

[gsxr]

Pin 6: code 21 may be an internal fault with the ASR pump itself. Uh-oh. This is pretty rare. Hopefully the light stays off and the fault code goes away.

Pin 7: code 6 is for the NSS (S16/1). Hopefully it only needs adjustment, OR new shift linkage bushings (should be zero play). NSS is NLA but you may be able to repair yours, or I think Kurth sells a modified replacement.

 

[Efraim]

Check this thread for ASR code.
What does one make of these codes? | De-Coding

​

 

[emerydc8]

Have you tried letting it idle for ten minutes to see if the ASR light illuminates? I had a situation where the ASR light illuminated when the electric charge pump stopped running (the one under the brake master cylinder). This was a function of time—not distance. It was somewhere in the five-minute area. I think another forum member had a similar problem and it went away after bleeding the brakes and ASR port.

 

[chicky]

Hello emerydc8

I don't know if you were referring to me ... with my R129066, I also had the problem last year ... what it eventually led to was I had my indy remove the master cylinder to get to the electric charge pump, and upon opening found it had corrosion & dirt (i guess due to the car being a "garage queen" hardly used). The indy cleaned it up, reinstalled the (pre-bench bled) master cylinder. After which the bleeding the brakes including the ASR port.

All good after

 

[gerryvz]

Have you tried letting it idle for ten minutes to see if the ASR light illuminates? I had a situation where the ASR light illuminated when the electric charge pump stopped running (the one under the brake master cylinder). This was a function of time—not distance. It was somewhere in the five-minute area. I think another forum member had a similar problem and it went away after bleeding the brakes and ASR port.

Hello emerydc8

I don't know if you were referring to me ... with my R129066, I also had the problem last year ... what it eventually led to was I had my indy remove the master cylinder to get to the electric charge pump, and upon opening found it had corrosion & dirt (i guess due to the car being a "garage queen" hardly used). The indy cleaned it up, reinstalled the (pre-bench bled) master cylinder. After which the bleeding the brakes including the ASR port.

All good after

Good thread to read on this: ABS and ASR lights on | Troubleshooting and Diagnostics

 

[emerydc8]

Hello emerydc8

I don't know if you were referring to me ... with my R129066, I also had the problem last year ... what it eventually led to was I had my indy remove the master cylinder to get to the electric charge pump, and upon opening found it had corrosion & dirt (i guess due to the car being a "garage queen" hardly used). The indy cleaned it up, reinstalled the (pre-bench bled) master cylinder. After which the bleeding the brakes including the ASR port.

All good

Hi @chicky — I was thinking of @Trae from a post that is quite old now. Your focus on the charge pump is just what @Klink discussed in response to @Trae’s post below.

Post in thread 'ASR Light'

Jun 20, 2014

After letting my car sit for nearly three weeks, I started the car and heard the ASR pump run.
I knew what was coming next. . . ASR light illuminated.

I am prepared this time.
1. I bled the SP screw on the ASR pump with the engine OFF.
2. Hooked up my pressure bleeder to the brake fluid resivior.
3. Started engine with the SP valve open and bled till no brake fluid bubbles (very little fluid).
4. Closed SP valve.
5. Let ASR pump run for about 30 seconds.
6. Shut down engine and disconnected pressure bleeder.

Problem solved. No ASR light.
Hypothesis: Letting the car sit that long...

• Trae

• 

 

[Lavaone]

Will cold start and idle for 10 minutes as suggested later today and observe.

Where is the ASR pump hidden?

I replaced the brake fluid during Covid 19. Don’t recall bleeding the ASR pump and didn’t get the ASR light until recently .

I remember replacing the fluid in 2019 because the governor here in MA declared only allowed on the roads for “emergencies”. I found I needed and so located a used pressurized brake bleeder online about 40 miles away. I declared an emergency and drove down eerily empty highways and byways to buy the unit. It was apocalyptic.

 

[Lavaone]

Will cold start and idle for 10 minutes as suggested later today and observe.

Where is the ASR pump hidden?

I replaced the brake fluid during Covid 19. Don’t recall bleeding the ASR pump and didn’t get the ASR light until recently .

I remember replacing the fluid in 2019 because the governor here in MA declared only allowed on the roads for “emergencies”. I found I needed and so located a used pressurized brake bleeder online about 40 miles away. I declared an emergency and drove down eerily empty highways and byways to buy the unit. It was apocalyptic.

Started, idled for about 3 minutes and ASR lit.

Going to re-read ASR related threads and regroup. From what I’ve already read there’ll be a lot of tail chasing in my immediate future.

 

[gsxr]

There is a small, low-pressure ASR pre-charge pump located below the brake master cylinder.

The high-pressure ASR charge pump is internal to the main ASR unit behind the driver side headlight.

 

[Lavaone]

Thanks, the low pressure is what I was searching for.

 

[mmchann]

Replace your OVP Relay passenger side in front of firewall. $75

 

[gerryvz]

Replace your OVP Relay passenger side in front of firewall. $75

The V-8 W124 cars DO NOT have an OVP relay, like the inline-six W124s do.

Instead this functionality is included in the BM/GM (Base Module/General Module), one of four computers located inside the CAN box underhood.

 

[gsxr]

Replace your OVP Relay passenger side in front of firewall. $75

Vehicles with LH-SFI do not have an OVP relay. This functionality is integrated into the BM/GM power supply module inside the CAN box.

(ooops, Gerry and I were typing at the same time! LOL!)

 

[gerryvz]

Thanks, the low pressure is what I was searching for.

I had this issue with my low-pressure pump getting stuck and activating the lights. I described it in a thread here on the forum.

What you need to do is with a warm (or warming up) car, BEFORE the three-minutes after startup when the lights come on, you need to floor the car (i.e. do a skid while turning, or accelerate rapidly) so that the ASR system is activated and new fluid is moved through the system. This will help "unstick" the pump. This thing tends to happen when the car sits for months and is not used.

 

[chicky]

Hello Gentlemen

Please allow me to share pictures of my R129066 ASR charge pump cleaning:

 

[GRAEME JOHNSON]

What a very helpfull post Chicky , that job would be great as a detailed step by step how to
I assume the gaskets o rings etc are not available separately and have to be removed carefully
and re used
I think a lot of problems stem from the brake fluid not being changed properly eg the SP port
opened and the accumulator drained, mind you I have read of the SP bleed nipple snapping
in the ABS block so its hard to know what to do for the best
Perhaps a weekly full bore ASR engaging burn out should be part of the service scedule to keep
that brake fluid moving round the system !
Graeme Johnson

 

[chicky]

Hello Graeme Johnson

"that job would be great as a detailed step by step how to" ... I actually had my indy follow the repair procedure from the MB WIS ... while watching over him

With regards to the bleeding, we used a MityVac pressure bleeder and 3 liters of ATE brake fluid ...

"a weekly full bore ASR engaging burn out should be part of the service scedule to keep
that brake fluid moving round the system !" ... well since the start of the ME problem, I have not gone past 100kph as fuel is very expensive during my bi-weekly runs of about 40 kilometers ... but before that

Regards

 

[GRAEME JOHNSON]

Thank you for posting the extra pictures
I have a 40 000 mile 129066 myself and I think standing around and lack of CORRECT ASR specific
brake fluid changes have gummed up my pre charge pump as well
I am not sure I would be brave enough to split the pump but if I had the outlet pipe removed
I might pour brake cleaner down the inlet hose and let it sit then make up some sort of loop
with hoses and a funnel then use a battery to try and run the pump to flush clean brake fluid round
( or bugger it up compleatly )
I have an ASR service manual by Mercedes but there are no instructions on opening the pump
just replacement
Graeme Johnson

 

[chicky]

Thank you for posting the extra pictures
I have a 40 000 mile 129066 myself and I think standing around and lack of CORRECT ASR specific
brake fluid changes have gummed up my pre charge pump as well
I am not sure I would be brave enough to split the pump but if I had the outlet pipe removed
I might pour brake cleaner down the inlet hose and let it sit then make up some sort of loop
with hoses and a funnel then use a battery to try and run the pump to flush clean brake fluid round
( or bugger it up compleatly )
I have an ASR service manual by Mercedes but there are no instructions on opening the pump
just replacement
Graeme Johnson

Hi

Based on my personal experience, not opening up the pre charge pump and just "
pour brake cleaner down the inlet hose and let it sit then make up some sort of loop
with hoses and a funnel then use a battery to try and run the pump to flush clean brake fluid round" might result in not really cleaning the inside, please refer to the picture "ASR 24Jan2024 e and f" which shows a passage way with thick gum deposit ... which I had my indie "scrape/clean" out entirely.

food for thought

regards

 

[GRAEME JOHNSON]

I see what you mean, my worry is damaging the O ring or gasket but
O rings can be measured and replaced and gaskets cut from sheet
Was the gasket rubber ?
As you say better to remove that goop compleatly than loosen it with cleaners
then pump it round into the ABS block !
Thank you for shareing you experience with this problem

 

[chicky]

Hello again GRAEME JOHNSON

Have you tried asking MBClassic Center-Long Beach ? It would help if you knew the part number for the gasket and o-ring ... maybe Dave/gsxr would know.

Honestly, I would search and order the o-ring and gasket first before "removing & opening it up ... just to be sure

Regards