ABC issues. Please help!
01-04-2019, 11:50 AM
#1
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s55 amg, ml500, c230k
ABC issues. Please help!
I am running some ABC sds tests on my 2001 S55 and I have some questions as to what I am observing. As a preclude, my wife was receiving an ABC Visit Workshop error when she came home from work one day. On a restart I did at first notice some noise in the front right of the car but it has since gone away. Knowing the proclivity of these pumps to turn into a grenade, I immediately pulled the car out of service until I could chase the issue some more.
The error message has not repeated itself but it had stored errors on the rear valve block and a low pressure error. When I ran a system actuation test, it started at a 195 bar reading and it dropped to 74 bar before aborting. When I run a front/back actuation or a left/right actuation, the test completes with no errors and the pressure stays > 188 bar but, I notice the rear never comes to normal ride height in the front/back actuation. It always drops very low and stays there with only minor up/down movements. The front seems to go to through the full range. I did run the actuator voltage test for the front and back and they were all in the suggested ranges.
Would the rear valve block possible be the low pressure reading culprit?
The error message has not repeated itself but it had stored errors on the rear valve block and a low pressure error. When I ran a system actuation test, it started at a 195 bar reading and it dropped to 74 bar before aborting. When I run a front/back actuation or a left/right actuation, the test completes with no errors and the pressure stays > 188 bar but, I notice the rear never comes to normal ride height in the front/back actuation. It always drops very low and stays there with only minor up/down movements. The front seems to go to through the full range. I did run the actuator voltage test for the front and back and they were all in the suggested ranges.
Would the rear valve block possible be the low pressure reading culprit?
01-05-2019, 02:18 PM
#2
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You car might not be as sick as you think.
The first thing is to make sure the fluid level is right. It's an exacting thing to do. Shout if you're unsure.
Replacing the fluid and the filter is always a good idea.
What are the circumstances of the error / alerts? Does it happen when idling, at speed, on bumps or in corners?
The valve block is unlikely to cause low pressure readings; they just tend to cause sagging.
Low pressure might be down to the pump, but it might be the accumulators as well. There's a good check for them.
Nick
The first thing is to make sure the fluid level is right. It's an exacting thing to do. Shout if you're unsure.
Replacing the fluid and the filter is always a good idea.
What are the circumstances of the error / alerts? Does it happen when idling, at speed, on bumps or in corners?
The valve block is unlikely to cause low pressure readings; they just tend to cause sagging.
Low pressure might be down to the pump, but it might be the accumulators as well. There's a good check for them.
Nick
01-05-2019, 05:13 PM
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Hi Nick,
Thanks for your response.
I have checked the fluid level and it is in the range on the stick. I mitivac'd the fluid from the reservoir and replaced it with new pentosin and a new filter about 4 months ago. The actual red dashboard error occurred on one day only but, it did repeat after a restart on the same day. It occurred on a hot restart when the car was sitting on a slight uphill grade. The ambient temperature outside was approx 28C. It was accompanied by a slight tapping noise under the hood that may have been coming from the pump. Just couldn't tell. The car is no longer making the noise on restart.
What I did notice yesterday was, after the SDS tests, that some fluid was leaking from the rear valve block. After closer inspection I could see that the bottom 2 electrical connectors were saturated in hydraulic fluid. I cleaned the lines and connectors. After restarting, the car went up to it's original ride height. I'm thinking that the connectors may have been shorted?
My plan is to rebuild the rear valve block and see if that helps.
I'm interested in the procedure you are suggesting to test the accumulators. Is there a sequence in SDS that I would use or is there something else involved?
Eric
Thanks for your response.
I have checked the fluid level and it is in the range on the stick. I mitivac'd the fluid from the reservoir and replaced it with new pentosin and a new filter about 4 months ago. The actual red dashboard error occurred on one day only but, it did repeat after a restart on the same day. It occurred on a hot restart when the car was sitting on a slight uphill grade. The ambient temperature outside was approx 28C. It was accompanied by a slight tapping noise under the hood that may have been coming from the pump. Just couldn't tell. The car is no longer making the noise on restart.
What I did notice yesterday was, after the SDS tests, that some fluid was leaking from the rear valve block. After closer inspection I could see that the bottom 2 electrical connectors were saturated in hydraulic fluid. I cleaned the lines and connectors. After restarting, the car went up to it's original ride height. I'm thinking that the connectors may have been shorted?
My plan is to rebuild the rear valve block and see if that helps.
I'm interested in the procedure you are suggesting to test the accumulators. Is there a sequence in SDS that I would use or is there something else involved?
Eric
01-05-2019, 06:54 PM
#4
If your accumulators have never been replaced, its time to replace them. They will cause low pressure readings since when going over a dip/bump not enough pressure is supplied to the shocks due to failing/failed accumulators and that will log an error code. I've replaced all four of mine and changed the fluid/filter and now have no pressure codes.
01-09-2019, 12:43 PM
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As I don't have time right now to chase all 4 of the accumulators, would the rear ones be the most likely culprits causing issue with the rear strut functionality?
01-10-2019, 04:33 AM
#6
Yes but as stated it’s simply time due to age, to change all accumulators and rebuild the blocks , do it all now so you are good for another ten years
sounds like you are capable to diy so it’s not a huge deal if you aren’t paying a shop
sounds like you are capable to diy so it’s not a huge deal if you aren’t paying a shop
01-10-2019, 06:57 PM
#7
The rear accumulator is a pretty easy job. You drop one of the mufflers and the accumulator will be staring you in the face. From there it's the one hydraulic line and another bolt or two that holds the accumulator to the body.
I probably replaced mine in under an hour and it was my first time. My accumulator failure resulted in fluid being forced out of the reservoir, a common occurrence when the nitrogen from the accumulator escapes and forces itself out of the system via the reservoir. I would get a quick flash of a warning when going over speed bumps or large dips on the highway.
I probably replaced mine in under an hour and it was my first time. My accumulator failure resulted in fluid being forced out of the reservoir, a common occurrence when the nitrogen from the accumulator escapes and forces itself out of the system via the reservoir. I would get a quick flash of a warning when going over speed bumps or large dips on the highway.
