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I have a 2005 SL500 which is showing the red ABC message when hitting bumps. Using DAS, I see pressure low faults logged. Running the various ABC tests all pass, including the dynamic test and rodeo test.I feel a vibration when hitting bumps in the driver side foot well, but I don't have the characteristic whine everyone talks about for a bad pulse dampener. DAS has a test where it graphs the ABC pressure when you turn off the engine. In my car this seems to drop really fast. I would think the pulse damper would turn this into a smooth curve.
Would this be a sign of a bad pulse dampener? Seems like the only other possibility is the pump, which is quite expensive.
Some notes:
1) Car doesn't sag when parked. It drives fine other than the faults hitting bumps
2) Interior button for changing height works
3) All DAS ABC tests pass without raising any faults
4) Bouncing the car when DAS has disabled ABC gives a nice cushy feel. The wheel air pressure tanks seem fine
5) Logged low pressure seems to always match with a road bump and vibration in the floor board
Am I on the right track? This is my first foray into DAS.
P.S. I must say it was worth ~$200 for a C3 mux just to watch the dynamic and rodeo tests. Remote control of a car while sitting in a lawn chair is awesome!
An ABC fault while traversing bumps is a hallmark of a failed front or rear accumulator. You can test the accumulators with Star Diagnosis. Within the ABC menu go to Troubleshooting by means of complaints or symptoms > Handling characteristics > Vehicle damping too soft or spongy handling characteristics > Pressure change during pressure release, and then follow the instructions.
Sadly the car blew a hose or something during the test. Right now the car is all the way down with a puddle of fluid below it. I may have stressed it more running the diagnostics, but I'm happy it failed in the driveway and not on the highway. Strangely the blowout happened right where you shutoff the engine in the test.
After replacing a blown front right shock and the two accumulators, the car drives amazing well. I thought the car was smooth before, but after the work it feels like a new car. Thanks again to bobterry99 for the accurate diagnosis. For those out there who don't like ABC, drive a car where it is working correctly before judging. An SL with ABC can be a true pleasure to drive. I just completed a few hundred mile drive in rainy weather, traffic, and more than a few potholes. I couldn't be happier!
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