BuffaloTony Posted January 6, 2020 Report Share Posted January 6, 2020 Hi everyone, Thanks so much for participating in this forum, it has been very helpful for me as a first time hybrid driver. Loving my CMax so far, but a few weeks ago I hit the brakes really hard while sliding on some ice. As of that moment, everything about my brakes felt dramatically different. It was very weird the rest of the drive since I basically had to relearn my braking technique. The brake pedal itself now gives no resistance back to my foot based on how deep or hard I press it. Before this happened, it felt like that was pressing against air-resistance from the pedal with that normal hiss, it felt like every car I have ever driven. Now, none of that exists and the brake pedal feels like it is on a toy car. It still kind of brakes based on how deep I push the pedal down, but if I want a full stop I have to go to the floor, then the pedal springs back up as you'd expect. I can get 100%s still, I just have to control how gradually I brake. This is the only way to brake, though, if I really have to slam on them, it's pretty weak and of course goes right to the floor and you can feel the friction of the brakes. One of the go-to brake solutions would be to pump the brakes, but that is exactly the mechanism that no longer works. There is no more pumping the brakes, nothing pumps, there's no changing pressure, it just springs back, up and down, floor to top. I took it to a mechanic friend and he looked at everything within his knowledge of the system - he took the wheels off and things looked new, brakes engaging perfectly (from his perspective), he tested the booster, did an electrical test. It took him about four hours. It is tough because he had never driven it before, so it was tough for him to process how different it really is, which is very different. If he checked all that, to me that means it must be high up near the pedal itself? Has this happened to anyone else? Does anyone have an idea as to the solution? C-MaxA2 1 Quote Link to comment Share on other sites More sharing options...
C-MaxA2 Posted January 6, 2020 Report Share Posted January 6, 2020 Take it to a Ford dealer and ask this question. Your hybrid is not just any car with just normal brakes; it has 'regenerative braking' and that is what engages first in most braking situations. Sounds like something happened to that. Quote Link to comment Share on other sites More sharing options...
fbov Posted January 6, 2020 Report Share Posted January 6, 2020 Or... it could be the ABS/TCS/RSC system. Folks are familiar with ABS, anti-lock braking system. Your car also has TCS, traction control system, and RSC rollover stability control. Both of these use the ABS system, one to brake a spinning drive wheel, the other to brake when it thinks you're in a skid and might rollover. Mine died spectacularly when I hit a pothole... in 2104, on an October 2012 build date. Early RSC had issues; blowing it out got me to the head of the line. Or you might have damaged parts of the hydraulic system by braking very hard when there was no traction. Your description sounds a lot like what I got after bleeding brakes manually. You could move the pedal down farther, pushing the master cylinder seals into the rust part of the bore. Brakes were fine as long as you hit them hard enough for the damaged seals to close up. Pedal would drop waiting at a light. Both are dealer-only items, if only for diagnostics. Do you have a good, qualified C-max Ford service center nearby? Have fun, Frank Quote Link to comment Share on other sites More sharing options...
ptjones Posted January 6, 2020 Report Share Posted January 6, 2020 I notice when it rains my brakes get grabby at 5 mph and below, but goes away after a few stops. Maybe rust on the disks. Paul Quote Link to comment Share on other sites More sharing options...
plus 3 golfer Posted January 7, 2020 Report Share Posted January 7, 2020 (edited) 8 hours ago, BuffaloTony said: Hi everyone, Thanks so much for participating in this forum, it has been very helpful for me as a first time hybrid driver. Loving my CMax so far, but a few weeks ago I hit the brakes really hard while sliding on some ice. As of that moment, everything about my brakes felt dramatically different. It was very weird the rest of the drive since I basically had to relearn my braking technique. The brake pedal itself now gives no resistance back to my foot based on how deep or hard I press it. Before this happened, it felt like that was pressing against air-resistance from the pedal with that normal hiss, it felt like every car I have ever driven. Now, none of that exists and the brake pedal feels like it is on a toy car. It still kind of brakes based on how deep I push the pedal down, but if I want a full stop I have to go to the floor, then the pedal springs back up as you'd expect. I can get 100%s still, I just have to control how gradually I brake. This is the only way to brake, though, if I really have to slam on them, it's pretty weak and of course goes right to the floor and you can feel the friction of the brakes. One of the go-to brake solutions would be to pump the brakes, but that is exactly the mechanism that no longer works. There is no more pumping the brakes, nothing pumps, there's no changing pressure, it just springs back, up and down, floor to top. I took it to a mechanic friend and he looked at everything within his knowledge of the system - he took the wheels off and things looked new, brakes engaging perfectly (from his perspective), he tested the booster, did an electrical test. It took him about four hours. It is tough because he had never driven it before, so it was tough for him to process how different it really is, which is very different. If he checked all that, to me that means it must be high up near the pedal itself? Has this happened to anyone else? Does anyone have an idea as to the solution? Sure sounds like you damaged the Pedal Simulator Unit which "always provides pedal feedback to the driver through a consistent pedal force, by using a cam-follower mechanism that is independent of the type of braking being used." The cam-follower appears to be part of the brake pedal assembly ($300+). You can probably look underneath at the assembly and see if you can locate it. Edited January 7, 2020 by Plus 3 Golfer BuffaloTony and MDSF 2 Quote Link to comment Share on other sites More sharing options...
BuffaloTony Posted January 7, 2020 Author Report Share Posted January 7, 2020 16 hours ago, fbov said: Or... it could be the ABS/TCS/RSC system. Folks are familiar with ABS, anti-lock braking system. Your car also has TCS, traction control system, and RSC rollover stability control. Both of these use the ABS system, one to brake a spinning drive wheel, the other to brake when it thinks you're in a skid and might rollover. Mine died spectacularly when I hit a pothole... in 2104, on an October 2012 build date. Early RSC had issues; blowing it out got me to the head of the line. Or you might have damaged parts of the hydraulic system by braking very hard when there was no traction. Your description sounds a lot like what I got after bleeding brakes manually. You could move the pedal down farther, pushing the master cylinder seals into the rust part of the bore. Brakes were fine as long as you hit them hard enough for the damaged seals to close up. Pedal would drop waiting at a light. Both are dealer-only items, if only for diagnostics. Do you have a good, qualified C-max Ford service center nearby? Have fun, Frank That's the thing...they might be qualified but they aren't known to be trustworthy or that good in matters like this, which is why I have been hesitating to take it in. Quote Link to comment Share on other sites More sharing options...
BuffaloTony Posted January 7, 2020 Author Report Share Posted January 7, 2020 16 hours ago, fbov said: Or... it could be the ABS/TCS/RSC system. Folks are familiar with ABS, anti-lock braking system. Your car also has TCS, traction control system, and RSC rollover stability control. Both of these use the ABS system, one to brake a spinning drive wheel, the other to brake when it thinks you're in a skid and might rollover. Mine died spectacularly when I hit a pothole... in 2104, on an October 2012 build date. Early RSC had issues; blowing it out got me to the head of the line. Or you might have damaged parts of the hydraulic system by braking very hard when there was no traction. Your description sounds a lot like what I got after bleeding brakes manually. You could move the pedal down farther, pushing the master cylinder seals into the rust part of the bore. Brakes were fine as long as you hit them hard enough for the damaged seals to close up. Pedal would drop waiting at a light. Both are dealer-only items, if only for diagnostics. Do you have a good, qualified C-max Ford service center nearby? Have fun, Frank That's the thing...they might be qualified but they aren't known to be trustworthy or that good in matters like this, which is why I have been hesitating to take it in. Quote Link to comment Share on other sites More sharing options...
fbov Posted January 7, 2020 Report Share Posted January 7, 2020 Well... if you're actually in Buffalo, I can suggest a dealer in Rochester... Quote Link to comment Share on other sites More sharing options...
plus 3 golfer Posted January 8, 2020 Report Share Posted January 8, 2020 (edited) On 1/7/2020 at 7:43 AM, BuffaloTony said: That's the thing...they might be qualified but they aren't known to be trustworthy or that good in matters like this, which is why I have been hesitating to take it in. There’s nothing “magic” about the control systems. The dealer though is generally not a cost effective way to replace parts. They’ll likely charge you at least $100 for diagnostic services, MSRP on parts (if it is brake pedal assembly $453) and likely $100 an hour for labor. Total might be around $800 with tax. This appears to be assembly part # CV6Z-2455-A. You might be able to find one at a salvage yard and put it in yourself. Go talk to the parts guy and have him look up the brake pedal assembly and whether one can order / replace the cam follower unit (assuming it’s bad). Also, your mechanic friend should be able to determine if that cam-follower is functional. Having looked at mine, there is wheel that as the pedal is pushed in follows a track. It appears that as the wheel moves along the track it pushes in a piston enclosed in a cylinder which likely gives the brake pedal a normal feel even though the pushrod is not engaged. There appears to be a bolt holding the wheel to the piston rod and perhaps can be replaced. The piston housing seems permanently attached to the brake assembly. In normal braking, If if the ABS control unit needs to apply the friction brakes (even though the pedal isn’t depressed far enough to engage the pushrod) it does so by a solenoid which pushes in the pushrod and then via valves, regulates pressure to rear and front brakes. So, even if the normal brake pedal feel is absent, your ABS should function correctly (and apparently it does). Edited January 9, 2020 by Plus 3 Golfer Quote Link to comment Share on other sites More sharing options...
BuffaloTony Posted January 8, 2020 Author Report Share Posted January 8, 2020 19 hours ago, fbov said: Well... if you're actually in Buffalo, I can suggest a dealer in Rochester... What dealer in Rochester? That's where I work... Quote Link to comment Share on other sites More sharing options...
fbov Posted January 9, 2020 Report Share Posted January 9, 2020 Look for a PM. Frank Quote Link to comment Share on other sites More sharing options...
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