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SLS - system description available? (archive)
[ Follow Ups ] [ M5 (E28) Message Board ] [ Msg. Board FAQ ]
Posted by Joe on May 24, 2002 at 10:24:24:

When I bought my M5, the SLS resevoir was about 0.5 liters low on hydraulic fluid. I added about 0.5 liters of Pentosin CHF 7.1 and there was no evidence of leaks in the system except for very slight weeping around the pump assembly.

Questions: 1) Would the 0.5 liters of missing fluid indicate one or both of the accumulators have punctured diaphragms? I assume the accumulators work the same as the brake accumulator, correct (30 bars or so of compressible nitrogen behind a diaphragm)? What is their individual capacity?

2) I've been tracing out the hydraulics and electrics. My 40 Amp relay works fine. The system isn't doing anything annoying (like changing ride height or imbalancing the car left to right) but I have no way of knowing what the system is supposed to do. The motor never seems to run. Is there a link available to a system description and wiring diagrams? What ignition position is required for the system to turn on?

3) Can someone post a brief description here of what, exactly, the SLS is supposed to do and how it does it under various load situations? The way the rear stabilizer bar is linked to the "switch" under the car, and the way the two accumulators are linked hydraulically through the "T-connector", albeit through small diameter hydraulic lines, leads me to believe that the SLS corrects for front-to-back load conditions but not side-to-side imbalances such as would be encountered in cornering. Is this correct? Perhaps the stabilizer/switch arrangement senses front to back imbalance and side to side imbalance is sensed/corrected hydraulically?

4) are both SLS shocks hydraulically the same, i.e., more hydraulic pressure extends the shock?

5) I assume the 155 bar switch at the pump interrupts the power to the motor, via interrupting the relay coils circuit. This is a high pressure safety cut-off, right?

6) Does the 30 bar switch at the T-connector control the motor/pump to set the system's hydraulic working pressure, i.e., the standby pressure held in the accumulators?

7) What does the "valve" do at the pump housing? Does this bypass pressure back to the resevoir in some load conditions?

8) anyone have a wire color code list for the system?

Thanks in advance -- I've never seen a system description so any info would help.

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