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ML55 - Stiff Steering - Faulty Traction Control Module?

88K views 183 replies 29 participants last post by  johnathan1 
#1 ·
Hello everyone,

Is there a way to temporarily disable the traction control module (BAS/ESP Module) on my truck?

The reason I ask is I am suffering from a stiff/heavy power steering.

There are a number of reasons for this but these are the ones I am currently considering:

  • Power steering pump
  • Power steering rack
  • BAS/ESP (Traction) Module

I have already changed the PS pump.

The steering rack may be next, once I order it from the US and it arrives here.

In the meanwhile:

The ML55 is equipped with speed sensitive steering which is meant to stiffen the steering as speeds increase and the system works by processing relevant signals/information from the BAS/ESP (Traction) control module and adjusting the steering assistance as required.

I'm currently working on the theory, perhaps misguided, that the traction control module is faulty and sending the wrong information to the sensor?/parametric valve? in the steering rack making the steering stiff and requiring an awful lot of effort.

If that is the case, I was wondering whether it may be possible to disable the traction control system temporarily to see if that fixes my stiff steering.

I don't want to purchase the traction control module ($780) and it turns out not to be my problem so I must eliminate all possibilities.

The next theory is in relation to replacing the power steering rack which is no cheaper - it retails from between $1000 (reconditioned) to $1800 (New).

Witek and 43sqd have been very kind in providing me with information to help me solve the problem and I attach the following documents which have influenced my thinking in this regard.

Please help me.:crybaby2:
 

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#2 ·
No you cannot disable SPS. Default state is stiff. Traction control module needs to apply current to Y10 solenoid to ease steering effort.

Right now you still have unresolved issue with pump replacement. Take care of that first. I would suggest installing old pump back. Then checking pressure.

Check connection at Y10. Measure resistance of Y10. Check current applied to Y10 at stand still and at 10 mph.
 
#10 ·
Yippppeeeeeeeeee!!!!!

...........Right now you still have unresolved issue with pump replacement. Take care of that first. I would suggest installing old pump back......
Witek, I followed your advice and reinstalled my old power steering pump plus the correct purge procedure..........and the whine/groan is totally gone!:dance:

I am ALSO pleased to report that power assistance does seem to have been restored somewhat to about 70% efficiency.

It's not perfect but I can live with it.

I shoved my mechanic out of the way and personally bled/purged the system to within an inch of it's life by turning the steering from lock to lock 100 times - I kid you not!:eek:

I am over the moon and totally in love with my truck again

ML55:sloppy:FAR888

Thank you ALL very much for your help and support!:thumbsup:
 
#4 ·
On your car the steering rack is a more common problem than the pump or the ESP module/CAN data lines.
 
#6 ·
It is on Y10, the SPS solonoid valve, this is mounted on the steering rack.
 
#12 ·
But his bycepts are much bigger now:D
 
#15 ·
Hello orn19,

I had an intermittently stiff power steering which then developed into a permanently stiff power steering. ie Little or no power assistance.

I bought a power steering pump out here in West Africa and had it installed.

My mechanic however did not purge the air out of the system after installing the new pump - Purging of air after installation involves lifting both front wheels off the ground and turning the steering wheel from lock to lock 30 times with the ENGINE OFF.

If you turn the engine on BEFORE doing the purge, you get air in the system resulting in a very load whine/groan indicative of trapped air in the system.

In addition to the whine, my power assistance with the new pump was EVEN WORSE than what I started off with!

I did a search of the Forum and somehow formed the view that it was either my steering rack (very expensive) or my traction control module (almost as expensive)/ML55 speed sensitive steering which was broken.

Before I changed those parts I decided to consult Witek and 43sqd; who were fantastically helpful and patient in helping me to diagnose andsubsequently solve the problem.

Witek advised that I re-install my old pump and purge the air out of the system.

I did so and my power assistance was restored to about 70% efficiency!

I can't explain WHY my old pump worked better once it had been re-installed but I can only guess that my power steering system originally had a lot of air in it which was correctly purged when the old pump was re-installed and that the new pump I had previously installed was not a genuine part.

That's my story.

I'm not an expert in this area but I can say that if your pump is not properly installed with the correct purge procedure it can cause the system to whine/groan and not operate properly and provide power assistance.

I am not sure what the situation is in your case.

I hope this helps
 
#16 ·
orn19

From what you just described your car has a weak steering pump.
 
#21 ·
Far
I have the same problem with steering in my ML55. I am trying to solve this problem along time, but still unsuccessful :(
I tried to change pump, ti fix rack, but the problem still exist. As I understand you solve this problem without changing Y10 (PML or SPS)?
 
#22 ·
Hello DAO,

Sorry to hear about your problem.

No, I did not change my Y10 solenoid or anything on the power steering rack.

I simply did as I described at post #10 of this thread.

Which was to correctly purge the system of air using the procedure in the pdfs attached thoughout this thread.

It worked for me but I don't know whether it will work for you.

Was your power steering purged for air upon installation of your new power steering pump and did you change your power steering reservoir and o-ring seal?
 
#23 ·
I don't know about the air in steering system, but I'am sure that mechanics/masters who changed pump for me didn't do the procedure which described in PDF. They just filled up the fluid till the top of reservoir, start the engine for a 5 seconds, and then add the fluid again till the top of reservoir.
Now I want to know can I do this procedure now, without changing the fluid?

PS Guys, sorry for my bad, bad english, but I need help to solve my problem, and the searching in our russian MB forums the same problem didn't help, so I have to talk with you guys with my bad english... (((
 
#24 ·
FAR, you are now my super-hero! new biceps, old pump!...legal eagle by day...pummels his own mechanic out of the way!...this read like a great novel. did you use your squeeling brake disguise in tandem with this dastardly challenge? if so, I will send you a cape for this outfit in time for all-hallows-eve. I'll shine a MB star in the sky the night before you can expect delivery. no ML problem is too diabolical for our FAR.
 
#25 ·
FAR, you are now my super-hero! new biceps, old pump!...legal eagle by day...pummels his own mechanic out of the way!...this read like a great novel. did you use your squeeling brake disguise in tandem with this dastardly challenge? if so, I will send you a cape for this outfit in time for all-hallows-eve. I'll shine a MB star in the sky the night before you can expect delivery. no ML problem is too diabolical for our FAR.
oreif you're killing me....:yelrotflmao::yelrotflmao::yelrotflmao:
 
#28 ·
I lifted up my front wheels, open the cover of reservoir, and turned the steering to full lock-to-Iock at least 30 times! Then putted down the car on a wheels, start the engine, and.... nothing! Problem is still exist! :(
You know actually I am not sure that my problem is similar to your...?! I will try to explain my problem. When you staying, and trying to turn (left or right doesn't matter) the steering sharply, the steering going stiff, but when you turning the steering slowly the steering going easy. Additional symptoms: when you doing u-turn on-site (forward-back, forward-back movements with turning the steering to full lock-to-lock) the steering going stiff in any case - sharply or slowly. And the last one symptom, after I turns on the left, and continuing my movement, usually the steering going to the center immediately, without any resistance, but my steering is going to the center, and on the some point suddenly goes stiff...
So thats my symptoms. :(
I don't understand whats happening with the car...
 
#29 ·
I THINK, I just got what you are saying here and I THINK I have the answer but could you explain it again and use different terminology?
 
#31 ·
Sorry, but my english is too bad... I do my best :(
Your english sir is a darn sight better than my russian lol. just trying to understand exactly what the problem is as I do not want to give bad advice.
 
#33 ·
I just re read your post and I need to ask this, have you had wheel alignment done recently especially with a view to camber?
 
#34 ·
I don't remember, because I bought this car one month ago, but before I bought my friend drove this car. He bought it in Jan 2007, from USA.

But I dont understand how the alignment can affect on stiff steering, especially when you staying at one place, without moving? ))
 
#35 ·
Is it the same problem when you are driving the car?
 
#37 ·
OK, when driving the car and turning full lock then release the steering wheel does the steering centralize on its own?
 
#40 ·
Resolving this issue will take concerted effort of ML55 owners both with working SPS and not. There is no diagnostics from MB therefore we have to develop our own strategy.

First order of business is to gather data from working and not working vehicles.

Find connector X18/33 and with ignition off and connector disconnected measure Y10 resistance in male connector, turn ignition on and measure voltage in female connector.

Switch meter to 10A amp scale, rig it inline with Y10, route leads inside and go on short road test. Report current at 20mph, 10mph and at idle.

When reporting values state if your SPS is working or not.
 

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#42 ·
I have checked!
1. Resistance of Y10 (male) is 9,0-9,5 Ohm
2. Voltage (female) is zero (the ignition is on, engine is started)! I was very surprised!
In that case I decided to stop the test, because I don't see any point to check current if there is no voltage!
Despite the test results I observe one strange thing! When the Y10 disconnected the steering is going a little bit harder (stiff) than when Y10 connected. But how it works if the voltage is zero?
 
#44 · (Edited)
Ok guys finally I've measured all data. Let's see:
1. The resistance of Y10 is ~10 Ohm (+/- 0.5) - turned off engine, and 20 Ohm - started engine
2. The voltage is zero on female, but when I turned off the engine, connect the connectors, start the engine and measure the voltage from leads I've received next values: on hold - ~8 Volts, 10 MPH - ~5.5, 20 MPH - ~5 Volts, 40 MPH - ~4 Volts (the higher the speed the lower the voltage):


3. The situation with current is very strange! It begin growing from starting the engine and not stopping, and depends on nothing! The value begins from 4 Amp and growing up by 0.01 Amp per second, like a clock:


And you know I observe one thing during the drive test (both standing and driving): when I measured the current the steering was very hard, but when I measured the voltage the steering was normal. Hmmm... ?!
 
#46 ·
Ok guys finally I've measured all data. Let's see:
1. The resistance of Y10 is ~10 Ohm (+/- 0.5) - turned off engine, and 20 Ohm - started engine
2. The voltage is zero on female, but when I turned off the engine, connect the connectors, start the engine and measure the voltage from leads I've received next values: on hold - ~8 Volts, 10 MPH - ~5.5, 20 MPH - ~5 Volts, 40 MPH - ~4 Volts (the higher the speed the lower the voltage):


3. The situation with current is very strange! It begin growing from starting the engine and not stopping, and depends on nothing! The value begins from 4 Amp and growing up by 0.01 Amp per second, like a clock:


And you know I observe one thing during the drive test (both standing and driving): when I measured the current the steering was very hard, but when I measured the voltage the steering was normal. Hmmm... ?!
There is something wrong with you meter connection. Resistance of Y10 cannot change with engine running or not.

To measure current you need to have meter connected in series with component.

How to measure current and power volt meter DMM
 
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