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Sedans Toyota Avalon Toyota Avalon Brakes, ABS, VSC, etc.
151 messages, Last post on Nov 24, 2009 at 6:06 AM
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Replying to: mermidon (Mar 02, 2009 1:05 pm)
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Replying to: Mr_Shiftright (Mar 02, 2009 7:06 pm) That could be the result of a low battery, poor battery positive and/or negative connections, poor connections to the ABS pumpmotor, or a "tired" ABS pumpmotor. Most modern day vehicles have a time-out system to prevent the prolonged use of the ABS pumpmotor in support of other, ancillary, functions such as TC, VSC, EBD, and BA. Basically "reserving" some portion of the ABS pumpmotor for its primary purpose/use. If some of these ancillary functions were highly active just prior to the need for ABS it is entirely possible that ABS capability would be foreshortened accordingly. And given the conditions stated it seems highly probable that TC would have been in use and maybe even VSC. The ABS pumpmotor very likely has a permanent magnet rotor and it doesn't take many overheating cycles to compromise the magnetic aspects of the rotor. Therefore a weakened pumpmotor functionality.
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Replying to: wwest (Mar 03, 2009 9:43 am)  Got any links for this? I need to know more about it.
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Replying to: Mr_Shiftright (Mar 03, 2009 9:52 am) No, NEVER. The problem could also have been a bit of debris blocking one of the ABS fluid pressure solenoid relief valves open slightly. Debris "washed" away, nothing for the techies to find wrong with the ABS. But my experience has been that an ABS failure light indication is often the very first indication that I need to replace a failing 12 volt battery. The ABS pumpmotor self-test puts a VERY heavy load on the 12 volt power source and distribution system and if the battery is even slightly marginal..... |
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Replying to: mermidon (Mar 02, 2009 1:05 pm) So, it was working as intended and it failed..but... it passed! This example is more proof that modern auto electronic systems are simply far too complicated. Scary trip. This should not happen in a modern sedan. But then, you never lost control of the car. An ABS working well gives you control as the wheels don't lock. Same for skid control. You might not stop but you go where you steer. These systems generally override any manual input. The sinking pedal allows this to happen within the systems therefore no error code. Probably. It may be as *wwest* has described it above. Electrical current is critical to the modern auto. A voltage drop could slow the response time and maybe still not show an error. In any case, you are along for the ride. This might happen in any ABS/VSC car depending on the system settings, electronics, etc. ....Where is my 1959 Buick......? 
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Replying to: fin (Mar 03, 2009 5:15 pm) Either in the junk yard or already melted down as scrap.. Exactly where it should be. The way I remember it cars of that era were more prone to brake pedal "fade" for a myriad of reasons. Blown master cylinder seal being the most common but not far above on eof the 4 brake shoe pistons. |
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Replying to: mermidon (Mar 02, 2009 1:05 pm) As wwest indirectly pointed out, if the system is over/short of voltage for whatever reason you should get a MIL in the dash along with a trouble code stored in memory. A MIL and corresponding DTC should appear for any abnormalities in the system (ABS, EBD, BA, VSC, etc.). What happened to “mermidon” was completely out of wack, especially for the fact that the tests done by the mechanic showed no symptoms at all. mermidon didn’t mention, however, if he noticed any warning beeps and/or lights in the dash just prior to the incident. My two cents: pay attention to the dash when starting your car. If any of the brake system icons don’t clear a couple of second after ignition, leave your car where it is and jump out of there! Amaury '08 Limited
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Replying to: amauhry (Mar 04, 2009 10:58 am) ABS/EBD/VSC/etc will not cause an MIL. |
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New front pads, rotors, calipers and rear pads. This after the RF caliper locked-up on us during a trip. Did all the work myself. Now the brake pedal travels to far and is too soft. So I bleed the brakes RR LR RF LF. I did this 4 times, and went through 2 large bottles of fluid. Still have the same brake softness and pedal travel. Funny thing is...I noticed that if I pump my brakes once... the brakes work perfectly. If I just apply them as I should, the pedal travels too far and the brakes are soft. 120k on the car and it has ABS and toyota's version of traction control, forgive me I don't remember the acronym...lol. System has been checked for leaks and the power booster is holding air pressure as it should... Any thoughts on how to get my brakes back to normal??? Thanks!!! 
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