Brake Fluid Flush

[krisk]

Perhaps I'm slow this morning and missing something obvious, or the car is more sophisticated than I ever imagined... but if I'm doing simple work like bleeding or changing pads, I'm going to be doing that with the car off, the ignition off, and so how in the world would it know or care that I'm possibly rotating the wheel or pushing fluid through?

Apologies for the long sentence.

This is my opinion (guess) based on research, deductive reasoning and personal experience from multiple brake pad changes, caliper/rotor/hub removal, brake fluid bleeding, etc. As such, do not rely on what I am about to say as absolute truth as I do not claim to have any insider knowledge.

I don't think bleeding the brakes, changing pads or rotating the wheel makes any difference if the car is in brake service mode or not. I've noticed no difference in brake service mode on and off performing those services. Similarly, I don't think removal of the regular or parking brake calipers alone without being in brake service mode will cause any problems. However, it is possible to activate the electronic parking brake or the electronic brake booster while the ignition is off, so there is potential for trouble if they are activated or deactivated when not properly mounted.

I don't think there is any issue with working on the brakes while not in brake service mode UNLESS you accidentally activate the brakes (electronic parking brake or electronic brake booster) both of which could be activated when the ignition is off. If you do so then the car will throw all kinds of DTC and braking capability will be drastically reduced (personal experience).

The service manual warnings for brake service mode state the following:

WARNING: Service actions on vehicles equipped with electronic parking brakes may cause
unexpected parking brake application, which could result in injury to hands or fingers. Put the
electronic parking brake system into service mode prior to servicing or removing rear brake
components. Failure to follow this instruction may result in serious personal injury.

WARNING: Service actions on vehicles equipped with electronic brake booster without
activating the brake system service mode may result in unexpected hydraulic brake application ora false leak detection DTC. This will significantly reduce the performance of the brake system.
Failure to follow this instruction may result in serious personal injury.

Sponsored

 

[Neggytive]

Vehicles with ABS need a fluid flush/service to keep the valves from freezing in place

It requires a scan tool to run the pump and actuate the valves

Brake fluid absorbs water over time, and it becomes corrosive in addition to less effective under high heat conditions.

It is one of the reasons when I do brake jobs at my shop I crack the bleeder screws and force the fluid out of the caliper when retracting the pads rather than push the crap that has settled in the system up into the lines. It also gives room for fresh fluid when I am done.

I also gravity bleed the system to get some of the old fluid out.

There are ways to check your brake fluid to see if it is in good shape, there are test strips, and you can even use a volt meter to measure voltage from the fluid in the reservoir to ground

.3 volts or less is good, anything over 300millivolts is a cause for concern and probably should have the fluid bled out a bit along with an ABS pump cycle test.

Most motorcycle manufacturers have been saying replace the fluid every 2 years for decades now, and I remember my wife's Boxster had a recommended service interval for brake fluid.

Harley had a recall IIRC on their bikes because they did not put it in the service schedule that the fluid needed to be flushed and the ABS pump serviced, now I think they are saying every 2 years

In a car without ABS it would be something you could do yourself pretty easily, but it is hard to get that ABS pump to work without a diagnostic scanner.

YMMV