Brake Fluid Flush

[WayneK]

I'm assuming those who track their cars probably flush the fluid more often than suggested in the service manual do to use and pad changes. On my other cars I use a Motive pressure bleeder to flush fluid through the calipers not concerned about the ABS module. With my other cars with ABS systems I simply pressurize the system with the pressure bleeder and open the bleeders at the calipers. On the 2024 Mustangs is it necessary to put the system in brake service mode if you simply want to flush fluid to the calipers when using the pressure bleeder not being concerned about the small amount of fluid in the ABS module?

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[PBBLASTER]

I'm assuming those who track their cars probably flush the fluid more often than suggested in the service manual do to use and pad changes. On my other cars I use a Motive pressure bleeder to flush fluid through the calipers not concerned about the ABS module. With my other cars with ABS systems I simply pressurize the system with the pressure bleeder and open the bleeders at the calipers. On the 2024 Mustangs is it necessary to put the system in brake service mode if you simply want to flush fluid to the calipers when using the pressure bleeder not being concerned about the small amount of fluid in the ABS module?

The main reason for with flushing DOT 3&4 brake fluid is its affinity for absorbing water then boiling at the caliper causing a catastrophic loss of brakes. I saw this happen to someone at a PDX. Two cars were totaled as the one with no brakes crashed into the car in front the end of the long straight. I was told it should be done every year for people who track their cars. Brake flushes was something I never skipped on my track car.

I never actuated the ABS module when I pressured bled my brakes (Motive) and never had a problem. It was a mazdaspeed3 so the system was probably different but if you don't let the fluid turn brown from neglect I do not see how you could have a brake fade problem if you follow the once a year schedule.

 

[Ryunker]

I'm assuming those who track their cars probably flush the fluid more often than suggested in the service manual do to use and pad changes. On my other cars I use a Motive pressure bleeder to flush fluid through the calipers not concerned about the ABS module. With my other cars with ABS systems I simply pressurize the system with the pressure bleeder and open the bleeders at the calipers. On the 2024 Mustangs is it necessary to put the system in brake service mode if you simply want to flush fluid to the calipers when using the pressure bleeder not being concerned about the small amount of fluid in the ABS module?

Brake service mode is irrelevant on brake fluid flushes. As far as the ABS module, well it is the master cylinder on this car so it will be flushed no matter what. Final bleed if necessary is done thru the scanner.

 

[HWill]

I had asked about this previously as it seems to be confusing.

Here is what the Service manual states:

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 or
a 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.

Here is a Note about bleeding:

NOTE: This mode "Brake Service Mode" is required to deactivate the brake boost and allow the entire brake system to bleed manually. (This is the part that is confusing to me.)

All of these warnings and notes are listed at the beginning of the brake chapters.

I need to replace a front caliper and from everything in the manual it states to activate "Brake Service Mode" before removing but deactivate after you install all of the new components. Then you carry out the brake system pressure bleeding using the diagnostic scan tool following the on
screen instructions.

I'm not sure if the scan tool puts the vehicle into "Brake Service Mode".

I also have the Motive bleeder I had planned on using if Forscan doesn't work.

And for vehicles equipped with 4 or 6 piston brake calipers, bleed the inner bleeder screw first,
followed by the outer bleeder screw.

 

[Ryunker]

I had asked about this previously as it seems to be confusing.

Here is what the Service manual states:

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 or
a 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.

Here is a Note about bleeding:

NOTE: This mode "Brake Service Mode" is required to deactivate the brake boost and allow the entire brake system to bleed manually. (This is the part that is confusing to me.)

All of these warnings and notes are listed at the beginning of the brake chapters.

I need to replace a front caliper and from everything in the manual it states to activate "Brake Service Mode" before removing but deactivate after you install all of the new components. Then you carry out the brake system pressure bleeding using the diagnostic scan tool following the on
screen instructions.

I'm not sure if the scan tool puts the vehicle into "Brake Service Mode".

I also have the Motive bleeder I had planned on using if Forscan doesn't work.

And for vehicles equipped with 4 or 6 piston brake calipers, bleed the inner bleeder screw first,
followed by the outer bleeder screw.

Scanners can put the system in service mode, along with a sequence of brake pedal and key cycles, but memory sucks for the sequence.

Had my brake booster replaced as it failed, tech showed me the bleeding procedure with the Ford scanner (laptop). Never opened a bleeder screw.

 

[msquad]

Not sure if this helps, but had seen this vid on how to put in brake maint mode...
2024 Ford Mustang: How To Enable Brake Maintenance Mode

 

[WayneK]

Ryunker,

Have you successfully done a flush as you described without any issues?

 

[Ryunker]

Ryunker,

Have you successfully done a flush as you described without any issues?

I am a retired tech, done oodles of flushes on brakes, it is overlooked on so many vehicles. I have a snapon pressure flusher, but really the open bleeders and gravity is by far the best. Just don't rotate a wheel/rotor with the bleeders open or the electric brakes kick in. Same on all the cars with electronic parking brakes. To answer, no, not yet as I drive my DH like an old lady.

 

[HWill]

Scanners can put the system in service mode, along with a sequence of brake pedal and key cycles, but memory sucks for the sequence.

Had my brake booster replaced as it failed, tech showed me the bleeding procedure with the Ford scanner (laptop). Never opened a bleeder screw.

So did the scan tool put the vehicle into "service mode" for the bleed procedure? I asked a tech today and they pretty much stated any brake work requires you to place the vehicle in "service mode".

Many will say if you can do it through a scan tool or Forscan then that is the best and simpliest way to bleed the breaks.

 

[Ryunker]

So did the scan tool put the vehicle into "service mode" for the bleed procedure? I asked a tech today and they pretty much stated any brake work requires you to place the vehicle in "service mode".

Many will say if you can do it through a scan tool or Forscan then that is the best and simpliest way to bleed the breaks.

Can not say for sure, but my car (DH) brake system is a new animal. There is not a master cylinder or brake booster. "Service mode" shuts off the electronic brake system in cars as well as takes pressure off the caliper system, thus would disable the entire brake system. Yes it can be over ridden hydraulically in case of emergency.

As said earlier, had my "electronic brake booster" (new name for ABS module) replaced under warranty due to communication issues. The tech at the dealer is a buddy of mine, after the "EBB" was replaced, bleeding was only done electronically with the scanner so it could not be done in "service mode". Bleeders were never opened.

Brake work on the brakes at the wheel would always require car in service mode like caliper or brake pad removal or service.

As far as a flush, I would do it by gravity. Raise the car and open bleeder screws and keep the brake system full of fluid, brake fluid will drain statically from the bleeder screw.

 

[krisk]

Ryunker,

Have you successfully done a flush as you described without any issues?

I’ve done a full brake fluid flush on my 2024 GT PP using a Motive pressure bleeder without putting it in brake service mode. I did it prior to realizing there was a brake service mode which can be activated. I have since bled the brakes with the service mode activated. I don’t know if it makes any difference for bleeding to have service mode activated or not, but neither way caused me any problems.

I would definitely put it in service mode prior to removing any brake components. Failing to do so will give you all sorts of DTCs when you start the car up. Also, the service manual warns that working on the system without activating service mode can result in sudden and unexpected hydraulic or parking brake application. I experienced the many DTCs when removing the brakes on my car without activating service mode. Since then I activate it any time I am touching the brakes. Better safe than sorry.

Here’s the procedure for activating and deactivating service mode. I’ll also try to attach the pages from the service manual for those who, like me, prefer a printout when working on the car.

Activating:
1. Turn ignition ON.
2. Press/push EPB switch while pressing brake pedal to release electronic parking brake.
3. Release brake pedal and EPB switch.
4. Hold down accelerator pedal and press the EPB switch.
5. Continue to hold down accelerator pedal and press the EPB switch.
-Turn ignition OFF and back ON within 5 seconds.
-Turn ignition OFF.
6. Release accelerator pedal and EPB switch.
7. Turn ignition ON.

Deactivating:
1. Turn ignition ON.
2. Press and hold down the accelerator pedal and pull up the EPB switch.
3. Continue to hold down accelerator pedal and pull up the EPB switch.
- Firmly press brake pedal and hold for at least 1 second
- Release brake pedal.
- Turn ignition OFF and back ON within 5 seconds.
- Release the accelerator pedal and EPB switch.
- Turn ignition ON.

 

[Japeatr]

I’ve done a full brake fluid flush on my 2024 GT PP using a Motive pressure bleeder without putting it in brake service mode. I did it prior to realizing there was a brake service mode which can be activated. I have since bled the brakes with the service mode activated. I don’t know if it makes any difference for bleeding to have service mode activated or not, but neither way caused me any problems.

I would definitely put it in service mode prior to removing any brake components. Failing to do so will give you all sorts of DTCs when you start the car up. Also, the service manual warns that working on the system without activating service mode can result in sudden and unexpected hydraulic or parking brake application. I experienced the many DTCs when removing the brakes on my car without activating service mode. Since then I activate it any time I am touching the brakes. Better safe than sorry.

Here’s the procedure for activating and deactivating service mode. I’ll also try to attach the pages from the service manual for those who, like me, prefer a printout when working on the car.

Activating:
1. Turn ignition ON.
2. Press/push EPB switch while pressing brake pedal to release electronic parking brake.
3. Release brake pedal and EPB switch.
4. Hold down accelerator pedal and press the EPB switch.
5. Continue to hold down accelerator pedal and press the EPB switch.
-Turn ignition OFF and back ON within 5 seconds.
-Turn ignition OFF.
6. Release accelerator pedal and EPB switch.
7. Turn ignition ON.

Deactivating:
1. Turn ignition ON.
2. Press and hold down the accelerator pedal and pull up the EPB switch.
3. Continue to hold down accelerator pedal and pull up the EPB switch.
- Firmly press brake pedal and hold for at least 1 second
- Release brake pedal.
- Turn ignition OFF and back ON within 5 seconds.
- Release the accelerator pedal and EPB switch.
- Turn ignition ON.

Thanks for attaching the procedure!

 

[WayneK]

Krisk,

Thank you for all the information you've provided. I couldn't imagine that the system would not pass fluid using the Motive without putting into brake service mode but didn't want to try until someone confirmed it.

 

[krisk]

One thing I did fail to mention about brake service mode is not only will it generate DTCs if you remove components without it activated, but the brake system will not function properly either.

The first time I removed the brakes without activating brake service mode, I had no problems removing or reinstalling the components. Everything went fine until I started the car up, and the dashboard lit up like a Christmas tree with warnings about all sorts of functionality being disabled. I tried driving the car, and the brakes worked, but with significantly reduced power. I tried disconnecting the battery overnight to reset the car, and that did NOT fix it. Once I cleared all the codes with Forscan, everything went back to working normally.

The next time I removed the brakes I activated brake service mode, and had no issues with DTCs or reduced functionality. Moral of the story is to learn from my mistake and always activate brake service mode when working on the brakes!

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