Ford Fusion did the sudden loss of brakes thing...am I screwed because its the ABS module?

[Eddo Rogue]

I went to drive the fusion after a long time of not and suddenly pedal was super low. Front pads were fresh, rear worn. I swapped in fresh rear pads (carefully repacking in the piston), and pedal was even lower smh. This is the kind of luck I have been having in general lately. I'm in a mechanics slump.

Anyways did some research and it could be a bad caliper, master cyl, or dreaded ABS module. Caliper check says clamp the lines and if you have pressure, release one at a time until you dont. I was 0 for 4 on that. Checked the master cyl, fluid was low and nasty...I soaked it up, topped off fresh fluid and did a half ass bleed. No dice.

I'm thinking maybe I can get lucky giving it a good thorough bleed as a first shot, but doubt I should be so lucky given current patterns. It does pressure up if I pump the pedal, but dont hold long.

I guess I am asking if its worth even bothering or should I get a new master cyl first and save some brake fluid...and if that dont work, hunt down an ABS module...or tow it to carmax....every bushing and bearing in the front end needs replacement too.

 

[pentode]

I can't speak very much to cars with ABS but I have a car that once had similar symptoms. Does the master seem to lose fluid? But no obvious leaks? Mine had a rear seal on the master that was leaking intermittently. Pull the vacuum line and look for fluid in the brake booster (assuming any of the previous assumptions were true).

 

[Eddo Rogue]

I can't speak very much to cars with ABS but I have a car that once had similar symptoms. Does the master seem to lose fluid? But no obvious leaks? Mine had a rear seal on the master that was leaking intermittently. Pull the vacuum line and look for fluid in the brake booster (assuming any of the previous assumptions were true).

I did not see any leaks at the time, but maybe there is some seeping I missed. If anything I suspect the front calipers, but they're dry.

I haven't lost any fluid since the initial top off/bleed...But I have not been driving it either due to lack of brakes.

If a good bleeding doesnt work, I will take a close at the calipers before throwing a master cylinder at it.

I'm ordered a vacuum bleeder and got my little cousin on standby as a pedal pumper for this weekend.

 

[Sharky]

if there is air in the ABS unit you will need to pressure bleed the system. the ABS unit is
difficult to bleed otherwise from what my mechanic buddy told me ?????

 

[19Walt93]

We had to put the ABS in bleed mode first. Did you do that?

 

[Uncle Gump]

Air just doesn't mysteriously appear in a brake hydraulic system. It simply can't happen.

Air only gets in if the system was opened up (and im not talking about the reservoir cap)... or has a leak somewhere.

 

[Eddo Rogue]

We had to put the ABS in bleed mode first. Did you do that?

No, How do I do that?

 

[Eddo Rogue]

Air just doesn't mysteriously appear in a brake hydraulic system. It simply can't happen.

Air only gets in if the system was opened up (and im not talking about the reservoir cap)... or has a leak somewhere.

I think air got in from fluid being too low in the master cyl, but didnt notice any leaks at first glance...not sure where it went..

 

[Mechrick]

Throw a master cylinder at it and see what happens.

If it's an ABS concern it will be the HCU and not the module. Many times you can remove your module from your HCU and swap in a replacement HCU. To bleed, do the base brake system first with the caliper bleeders, then go find a gravel road and do some stops on gravel to activate the ABS and force it to purge air that way.

ABS HCU's very seldom fail, especially on Fords. GM is another story...

 

[Uncle Gump]

I think air got in from fluid being too low in the master cyl, but didnt notice any leaks at first glance...not sure where it went..

Even low... still zero chance that let air in. An empty reservoir is a different.

As disc brake pads wear... fluid in the reservoir lowers to fill the void left behind from the now missing brake pad lining.

A decent scan tool will have an ABS system bleed function built into its software.

 

[WutUp Clegg]

I would say it's your master cylinder. For your pedal to drop like that, sounds like the piston might be leaking, but I'm not a Fusion specialist.

 

[19Walt93]

No, How do I do that?

With a scan tool, I don't remember the process, though.

 

[Eddo Rogue]

Thanks everyone, excellent suggestions and directions to go from here.

Maybe hoop dream, but would it help if I cracked the bleeders and let it gravity bleed overnight? I can let her sit on jackstands wheels off.

Also has anyone used those Russell speed bleeders w the one way check valves? I ordered some to try...They were like $17 bucks.

 

[Eddo Rogue]

Throw a master cylinder at it and see what happens.

If it's an ABS concern it will be the HCU and not the module. Many times you can remove your module from your HCU and swap in a replacement HCU. To bleed, do the base brake system first with the caliper bleeders, then go find a gravel road and do some stops on gravel to activate the ABS and force it to purge air that way.

ABS HCU's very seldom fail, especially on Fords. GM is another story...

From what I read the abs module seems to be a somewhat common failure on these Fusions and other models w same setup. I don't recall much info on the HCU, but do remember one forum guy mentioning to change it along w the ABS.

I think and hope its just the master cyl....again from what I've read, if there is any pressure at all, the ABS is ok....and I do have some pedal pressure, just not enough to drive at road speeds confidently. Stops fine shuffling it around the driveway....just really low pedal.

 

[Mechrick]

From what I read the abs module seems to be a somewhat common failure on these Fusions

Module, yes. I've seen a bunch fail over the last several years, most of them on F150's. None of them caused a low pedal.

There is a specific failure that has to take place for an ABS HCU unit to cause a low pedal, which is a dump valve hanging open. Very rare.

Is there evidence of contaminants in the brake system (master cylinder cap seal swollen/distorted)?