Owners of Mercedes-Benz cars enjoy an awesome driving experience and quality performance that rivals other brands. The iconic model set the pace for safety, electronics, and connectivity which other car companies soon followed.
Mercedes owners are familiar with the disturbing “ABC Drive Carefully” message that pops up occasionally. This is not a random message to be ignored. It is a warning sign of something being wrong with the Active Body Control system. The ABC system is responsible for mediating the hydraulic active suspension, a system drained to control vehicle body motions.
The ABC system is made up of the following parts: the hydraulic pump, accelerator sensors, hydraulic struts, control module and hydraulic lines. This feature is found on rear wheel drive Mercedes models. The ABC system must be maintained regularly following a strict protocol. One major issue that calls for this maintenance is the ABC pump. A defective pump needs to be replaced to prevent complications with the steering oil reservoir, acceleration and body roll. Usually, a pump replacement is accompanied by an ABC suspension flush, more commonly called the rodeo test. Flushing the ABC system is a procedure that involves bleeding the hydraulic fluid out of the system. This fluid is not meant to stay for a prolonged period because it gets old and dirty. Contaminated fluid knocks up sensors, damages pumps and ruptures pulsation accumulators and dampers.
Using a computer, our mechanics will activate the pump to send pressurized hydraulic fluid to all suspension struts. The result of this activity is the car appearing like its bucking bronco slowly (like a rodeo). The fluid movement controls the ride height and the damping force. The rodeo test, therefore, calibrates the suspension by continuous adjustment of the suspension height on each car corner. This rodeo movement allows the fluid to be flushed out completely. This process takes nothing over 20 minutes and running the test leaves the Benz running smoothly again after refilling the fluid.
A demonstration of us performing a rodeo test on a Mercedes Benz SL550 can be found below: