# Toyota has bigger problems **URL:** \ **Category:** PittSpeed Off Topic\ **Created:** [February 12, 2010, 10:20pm UTC](https://forums.speedlife.net/t/toyota-has-bigger-problems/204607 "2010-02-12T22:20:46Z")\ **Posts on this page:** 1\ **Showing post:** 9
**Author:** ![vw16vcabby](https://yyz2.discourse-cdn.com/flex034/user_avatar/forums.speedlife.net/vw16vcabby/32/5943_2.png) [@vw16vcabby](https://forums.speedlife.net/u/vw16vcabby)\ **Post date:** [February 14, 2010, 10:56am UTC](https://forums.speedlife.net/t/toyota-has-bigger-problems/204607/9 "2010-02-14T10:56:53Z")
> [@Why are man hole covers round?](https://forums.speedlife.net/t/why-are-man-hole-covers-round/41996/40): > > It does state that there is a hydraulic master cylinder for backup, but how long before they trust it that they do away with the mechanical backup? > > It’s coming whether we like it or not. thats the thing–even when it was employed–the hydraulic unit was still maintained. no car company is stupid enough to build a car that could go on the fritz electronically and leave all steering of braking rendered useless. because the family of said person who wrecks the car due to electronic failure would then own the company. just from a litigation standpoint–it would be bad business for a company to do that. calling the mercedes setup brake by wire is misleading. the system more or less monitors brake pedal stroke on the booster to try and decipher emergency situations. ultimatley it is tied in w/ the esp system. here is a run down of the mercedes system– The functions of the BAS brake booster (A7/7) are controlled using the components of the electrical/electronic system. In model 168, the voltage supply for the BAS control unit (N48) is via the fuse and relay box (F1). In models 129 and 140 via the base module (N1 6/1). In models 163, 170, 202, 208, 210, 215, 220 via the relay module (K40). In models 203 and 209 via the SAM control unit (N 10/1 In all vehicles with engines 112, 113, 605, 606, 611, 612, 613 and ESP, the BAS control unit function is integrated in the ESP control unit (N47-5). In models 163, 168, 203, 209, 215, 220 the BAS control unit function is integrated in the ESP control unit (N47-5). The BAS control unit receives input signals from the following components: ``` * ME control unit (via CAN data line) * Traction system control unit (via CAN data line) * BAS diaphragm travel sensor * BAS release switch ``` In the BAS control unit, the input signals are converted into output signals for the following components: ``` * BAS solenoid valve * BAS/ESP indicator lamp (via CAN data line) ``` On the basis of the input signals, the BAS (N48) or ESP (N47-5) control unit decides which of the 3 operating modes ``` * Normal mode * BAS pressure increase * BAS pressure reduction is to be activated. ``` Normal operation In this case, the brake application is not at the higher pedal speed (that requires activation of BAS). The solenoid valve in the BAS brake booster (A7/7) is de energized in the basic position. The system is ready for braking. Service brake and ABS function normally. This mode is also set if there is a fault in the BAS. BAS pressure increase From the speed of the brake pedal, the BAS control unit (N48) recognizes that the preconditions exist for activation of BAS. The BAS solenoid valve (A7/7y1) is activated by the BAS control unit (N48) and the brake booster produces the maximum brake assistance power. BAS is activated when the following conditions exist simultaneously: BAS pressure reduction The BAS control unit (N48) receives information from the BAS release switch (A7/7s1) that the emergency brake application has terminated. The BAS solenoid valve (A7/7y1) is no longer activated and the maximum braking assistance force is switched off. The normal brake servo assistance remains unchanged. BAS is switched off when one of the following conditions exists: ``` * Speed > 8 km/h ``` - BAS release switch is actuated - no current fault is detected. - the system is enabled (after self-test) - Pedal speed activation threshold exceeded --- _[View the full topic](https://forums.speedlife.net/t/toyota-has-bigger-problems/204607)._