Soft brake pedal, bad ABS unit?

[Nelson]

I’m working on a friends 2010 Dodge Journey 3.5 v6 2wd that has a soft brake pedal when running but firms up when Engine is off. While driving, The pedal will go nearly to the floor before the brakes grab but still stops good. There are no visible leaks anywhere, lines and calipers are all dry. Car has new pads front and rear, new front brake caliper hoses, new master cylinder and new booster. All four corners were bled with a pressure bleeder, went for a drive and made a few panic stops on gravel to engage the abs, then bled the brakes again.  All of this and still no change in the pedal feel. 

 

What I’ve done is looped the lines at the master cylinder with a spare piece of brake line, started the car and had a good firm pedal. So the new master cylinder is good and holding pressure. Then I removed the loop, hooked the lines back up and clamped the rubber hoses at all four wheels and had a soft pedal again. This leads me to believe that the abs hydraulic unit is bad as it’s the only thing between the master cylinder and hoses. Can anyone confirm my diagnosis or offer any more advice? Anyone changed the abs unit before and have any tips? Thanks in advance for any help you can offer!

[2late4u]

first off congrats on giving background info on the car and problem,a lot of poster dont give us any vech info, not sure on the abs question  but have heard that there can be a restriction on the caliper rubber hose where the clamp that holds the hose builds up rust under the clamp and restricts the flow or pressure delivered to the caliper, might want to examine all for hoses to see if that might be an issue since its a 2010 and in the north where there is salt used a lot..good luck on the problem

[Nelson]

Thanks for your input. The front brake hoses are new. Rear hoses visually look good and the brakes do not drag (car rolls free in neutral and while idling in gear with foot off the brake pedal) so I don’t suspect a hose issue. This car is actually from California and rust free. I inspected the brake lines from front to back and they look brand new, no leaks or corrosion. 

 

I drove the car on a long gravel/dirt road today and the abs works great when panic stopping. Actually the pedal is nice and firm when the abs pump kicks on but then goes soft again when it shuts off and returns to normal braking. I’m stumped and open to all suggestions anyone has. 

[Nelson]

Bump. Might be getting an ABS unit from a salvage yard to try. I’m out of ideas otherwise. 

[Nelson]

My buddy got an abs unit from a yard and I installed it a few hours ago. Now all the brake warning lights and check engine light are on, brakes are worse than before and the speedometer does not work. Went and looked at the receipt and they sold us one from a 2013 Journey which according to Rock Autos parts interchange is not the same part number. They list 2010-12 as interchangeable. Visually the parts are the same and everything hooked up fine. 

 

I’m going to look for an abs unit off a 2010-12 model and try that I suppose. Does the module need programmed? I don’t think so but it’s possible. Any and all input y’all on the forum can give me would be awesome! Thanks.

[bfurth]

I know that there is a computer initiated bleed procedure for a newly installed ABS module.  The correct procedure is 4 wheel bleed, ABS automated bleed, 4 wheel bleed again.  If you don't have a scan tool capable of initiating that bleed, take it to a shop.

[blissman20]

Any progress? I have the same issue 

[Nelson]

12 hours ago, blissman20 said:

Any progress? I have the same issue 

Nope, sorry. I reinstalled the original abs unit, ran the pump, bled all four wheels multiple times all with no improvement from how it was when the car was brought to me.

 

There’s no warning lights on the dash except the tire pressure indicator light and I’ve checked the tire pressures, they are fine. Speedometer is working again with the original abs unit installed. I don’t think the abs is to blame since it works fine and the pedal firms up when the pump runs. 

 

I couldn’t waste any more time on it so they are taking it to a shop. If the shop fixes it I’ll post what they found. 

[blissman20]

46 minutes ago, Nelson said:

Nope, sorry. I reinstalled the original abs unit, ran the pump, bled all four wheels multiple times all with no improvement from how it was when the car was brought to me.

 

There’s no warning lights on the dash except the tire pressure indicator light and I’ve checked the tire pressures, they are fine. Speedometer is working again with the original abs unit installed. I don’t think the abs is to blame since it works fine and the pedal firms up when the pump runs. 

 

I couldn’t waste any more time on it so they are taking it to a shop. If the shop fixes it I’ll post what they found. 

 Thanks! Yeah keep me updated.  I bought my journey in need of attention and just started to give it the attention it deserves and same issue. I know it’s not leaking nor is it the master because when I pump the brakes it doesn’t get better.  I think it’s something simple like a sensor that needs to tell the pump to turn on.  

[Nelson]

On 4/21/2019 at 11:08 AM, blissman20 said:

 Thanks! Yeah keep me updated.  I bought my journey in need of attention and just started to give it the attention it deserves and same issue. I know it’s not leaking nor is it the master because when I pump the brakes it doesn’t get better.  I think it’s something simple like a sensor that needs to tell the pump to turn on.  

Hey buddy just wanted to let you know I fixed the Journey today. Turns out the problem was the passenger side rear caliper. I took the wheel off and noticed a gap between the piston and inner brake pad suggesting that the piston was stuck and not applying the brakes on that corner.  I installed a new caliper, bled the brakes and now have a good firm pedal, stops like brand new. 

 

Definitely a learning experience for me. Would never have guessed a stuck caliper could cause a soft pedal. A good way to find if you have the same problem would be to unbolt one caliper at a time and have a helper push the brake pedal and see if the piston moves. I’ve used this method in the past to find bad calipers but didn’t bother on this car because I assumed it couldn’t be the problem. Live and learn. Good luck with your car!

[blissman20]

On 2019-04-30 at 7:24 PM, Nelson said:

Hey buddy just wanted to let you know I fixed the Journey today. Turns out the problem was the passenger side rear caliper. I took the wheel off and noticed a gap between the piston and inner brake pad suggesting that the piston was stuck and not applying the brakes on that corner.  I installed a new caliper, bled the brakes and now have a good firm pedal, stops like brand new. 

 

Definitely a learning experience for me. Would never have guessed a stuck caliper could cause a soft pedal. A good way to find if you have the same problem would be to unbolt one caliper at a time and have a helper push the brake pedal and see if the piston moves. I’ve used this method in the past to find bad calipers but didn’t bother on this car because I assumed it couldn’t be the problem. Live and learn. Good luck with your car!

 Awesome thanks! I’ll be doing the same, I bought a vacuum pump to help in bleeding the brakes 

[sppmaster]

On 1.05.2019 г. at 4:24 AM, Nelson said:

Hey buddy just wanted to let you know I fixed the Journey today. Turns out the problem was the passenger side rear caliper. I took the wheel off and noticed a gap between the piston and inner brake pad suggesting that the piston was stuck and not applying the brakes on that corner.  I installed a new caliper, bled the brakes and now have a good firm pedal, stops like brand new. 

 

Definitely a learning experience for me. Would never have guessed a stuck caliper could cause a soft pedal. A good way to find if you have the same problem would be to unbolt one caliper at a time and have a helper push the brake pedal and see if the piston moves. I’ve used this method in the past to find bad calipers but didn’t bother on this car because I assumed it couldn’t be the problem. Live and learn. Good luck with your car!

I have absolutely the same issue with the brakes of Fiat Freemont (It's just a twin car of Dodge Journey for Europe). That soft pedal came after brake fluid and the rear brake pads were changed at the service shop. Never had issues before that point. The pedal was always firm and the max movement that was possible was around 2-3 inches. Now it goes down all the way to the floor and is spongy. I don't know if the reason could be a defective caliper but when the brake system was tested on brake stand all wheels stopped evenly with the needed force. No one is able at the moment to resolve the issue for 8 months. I'm lost.

I've even made a video of this low brake pedal. Can you check and confirm the pedal movement and behaviour.

 

Edited August 13, 2019 by sppmaster

[sppmaster]

Does anyone read this thread. I've found another possible reason here in the first post.

https://www.chryslerminivan.net/threads/read-this-before-doing-your-rear-brakes.159561/

To be honest I cannot fully understand what that person tried to explain about the rear brakes and the gap between the pads and the piston and how he possibly fixed it.

Can anyone help.

[jkeaton]

1 hour ago, sppmaster said:

Does anyone read this thread. I've found another possible reason here in the first post.

https://www.chryslerminivan.net/threads/read-this-before-doing-your-rear-brakes.159561/

To be honest I cannot fully understand what that person tried to explain about the rear brakes and the gap between the pads and the piston and how he possibly fixed it.

Can anyone help.

 

What are your symptoms?

 

[sppmaster]

12 hours ago, jkeaton said:

 

What are your symptoms?

 

Eight months ago I went to the official dealer service shop for yearly maintenance. The mechanic changed the brake fluid and the rear brake pads.
Since then when I press the brake pedal the car slows down and stops, but if I continue to press the pedal, it goes down to the floor and make hissing sound/noise as if compressed air is going out of it (like a tyre pump).
I returned to the service shop and explained all of this. They made a test drive and said all is normal and it takes time the new brake pads to self adjust to the brake rotors.
I've driven around 50 km in the city and nothing changed. The next day I was at the service shop again in order to make sure there is no air left inside the brake system. The car was at the service shop the whole day and I was told later that all air is out and it is normal the pedal goes down to the floor. According to the mechanic I should drive 500 km before the brake pads self adjust and pedal stops going down to the floor. I think this is not normal and very hazardous to drive this way.

Already passed 700 km but no change. The brake pedal still goes down to the floor when I press it. The FIAT workshop is unable to solve or repair it. Several days later the car was at the service shop for the third time after changing the rear brake pads. The air bleeding was performed and one of the rear brake apparatus was serviced and checked but nothing has changed. Cost me 70 euro for nothing. People from the workshop say this behaviour is normal on all Freemonts.

I didn't have that problem before and the brake pedal was firm and didn't go to the floor.

Already eight months and no solution to this.

Edited September 12, 2019 by sppmaster

[Nelson]

7 hours ago, sppmaster said:

Eight months ago I went to the official dealer service shop for yearly maintenance. The mechanic changed the brake fluid and the rear brake pads.
Since then when I press the brake pedal the car slows down and stops, but if I continue to press the pedal, it goes down to the floor and make hissing sound/noise as if compressed air is going out of it (like a tyre pump).
I returned to the service shop and explained all of this. They made a test drive and said all is normal and it takes time the new brake pads to self adjust to the brake rotors.
I've driven around 50 km in the city and nothing changed. The next day I was at the service shop again in order to make sure there is no air left inside the brake system. The car was at the service shop the whole day and I was told later that all air is out and it is normal the pedal goes down to the floor. According to the mechanic I should drive 500 km before the brake pads self adjust and pedal stops going down to the floor. I think this is not normal and very hazardous to drive this way.

Already passed 700 km but no change. The brake pedal still goes down to the floor when I press it. The FIAT workshop is unable to solve or repair it. Several days later the car was at the service shop for the third time after changing the rear brake pads. The air bleeding was performed and one of the rear brake apparatus was serviced and checked but nothing has changed. Cost me 70 euro for nothing. People from the workshop say this behaviour is normal on all Freemonts.

I didn't have that problem before and the brake pedal was firm and didn't go to the floor.

Already eight months and no solution to this.

If the problem started right after having the rear brakes worked on then the problem is most likely with the rear brakes unless something else happened coincidently (unlikely but possible). I would unbolt one of the rear calipers and have a helper push the pedal a few times while you watch the piston, it should slowly move outward with each pump of the pedal. Check them both one at a time. 

 

I’d also inspect all the rubber caliper hoses for bulging with the engine running and a helper holding the brake pedal down. You could also take a piece of brake line and loop the lines at the master cylinder (I mentioned this in my first post in this thread), if the pedal feels good then you know the master cylinder is good. 

 

It’s likely the problem is with the rear calipers. I’m not a fan of this style where the pistons screws in and out, I’ve seen many of them seize up during normal brake service like changing pads, on many cars not just Dodge Journeys. Let us know what you find. 

[sppmaster]

As I have read a lot of writings on the subject over the Internet I wonder if this low and spongy brake pedal could be caused by a bad adjustment of the parking brake or it could be the ABS module. The second thing I observed after the rear brake pads change was the completely maladjusted parking brake. I had to pull 8-10 pins to hold the car. Before that it needed only 2-3 pins. The brake stand test showed irregularity of 35% between the left (lower stopping force) and right rear brakes for the parking brake.

I don't have the option to change the ABS and the mechanic from the service shop told me it's OK after it was tested.

I've tried with another brake master cylinder but just got the same low and spongy  brake pedal.

[NavalLacrosse]

I noticed this issue too when I changed my rear brake pads. 

When I bought the car, there were no issues (that I noticed).
 

After I changed the rear pads and rotors, I noticed immediately the same issue- exactly as OP describes. 

I thought the cause to be one of two things:

1) When compressing the rear caliper, I used a c-clamp... and really pressed it hard. it wasn't till later I rented the turning brake tool.

2) after the job, I decided to bleed the brakes with my dad. We ingested air at the reservoir, and re-compressed the caliber to force the air out the top, which seemed to work.

Took the car on the road for the first time and knew something was wrong. Exactly as described- derivable with no issues, but the pedal just slowly sinks to the floor if i press my foot on it while stopped.

I've just learned to ignore it. I'll bleed the whole system one day via a mechanic, but until then it's so subtle I'll just keep driving it.

[2late4u]

On 9/11/2019 at 7:47 PM, sppmaster said:

Does anyone read this thread. I've found another possible reason here in the first post.

https://www.chryslerminivan.net/threads/read-this-before-doing-your-rear-brakes.159561/

To be honest I cannot fully understand what that person tried to explain about the rear brakes and the gap between the pads and the piston and how he possibly fixed it.

Can anyone help.

as he stated put both rear tires in the air, both wheels off and have someone press on the brake and spin the hubs if one of them still spin ,then watch when he releases the brake pedal and pushes on it again to see if the caliper is tightening onto the rotor if not then you have a froze caliper or a bad one ,also check the caliper pins on both rear to make sure they are greased

[sppmaster]

27 minutes ago, 2late4u said:

as he stated put both rear tires in the air, both wheels off and have someone press on the brake and spin the hubs if one of them still spin ,then watch when he releases the brake pedal and pushes on it again to see if the caliper is tightening onto the rotor if not then you have a froze caliper or a bad one ,also check the caliper pins on both rear to make sure they are greased

Thank you.

As i triple read the post I think I fully understood the actions of that guy. But he says that he used another tool and drive ratchet to push the pistons and not recommended by the manufacturer special tool that rotates the piston while pushing it down. And after that he got that low pedal and he says that he pushed the pistons too far and that was a mistake. But he explains that all of this was reversible by turning the piston counterclockwise. After doing that the low brake pedal disappeared for him.

Honestly I don't understand how is it possible that a gap can exist between the piston and the brake pad. The only thing that make sens to me is to think that using an inappropriate tool could lead to a gap inside the parking brake mechanism of the rear caliper and that gap is somehow responsible for that pedal behavior but it's just my thinking.

Edited September 26, 2019 by sppmaster

[2late4u]

if the caliper piston is not fully extending then it wont tighten onto the rotor....also look at the front of the caliper piston if there is groves like a plus then these are the ones you have to turn in i bought a cheap cube tool that has different nubs on it that fit into the groves and then use a ratchet to turn . here is piture of it about $7.at harbor fright or most part stores

[sppmaster]

3 hours ago, 2late4u said:

if the caliper piston is not fully extending then it wont tighten onto the rotor....also look at the front of the caliper piston if there is groves like a plus then these are the ones you have to turn in i bought a cheap cube tool that has different nubs on it that fit into the groves and then use a ratchet to turn . here is piture of it about $7.at harbor fright or most part stores

In case the piston doesn't tighten onto the rotor shouldn't be there a little brake force on that wheel. What is supposed to happen when the piston is turned in.

Edited September 27, 2019 by sppmaster

[sppmaster]

As my issue with the brakes is still not resolved, I've started thinking there might be a problem with the ABS/ECU module. Maybe a stuck valve in the ECU causes the brake fluid to bypass internally and probably the low brake pedal is due to this. I don't have spare ABS/ECU module to try this theory but it seems very reasonable considering all other things I've done so far - master cylinder change, several brake bleedings performed, etc. Does anyone know if there is a detailed information about the ABS/HCU system and explanation of its work. Has anyone ever tried to change the ABS/ECU of his Dodge Journey and resolved the issue with the sinking brake pedal.

[2late4u]

1 hour ago, sppmaster said:

As my issue with the brakes is still not resolved, I've started thinking there might be a problem with the ABS/ECU module. Maybe a stuck valve in the ECU causes the brake fluid to bypass internally and probably the low brake pedal is due to this. I don't have spare ABS/ECU module to try this theory but it seems very reasonable considering all other things I've done so far - master cylinder change, several brake bleedings performed, etc. Does anyone know if there is a detailed information about the ABS/HCU system and explanation of its work. Has anyone ever tried to change the ABS/ECU of his Dodge Journey and resolved the issue with the sinking brake pedal.

so if this all started right after your brake job at the dealership and have been back and the said they need to break in for a while ( which is bullshit) i would go back and demand they fix what they messed up on their dime ...be nice but be firm and dont stand for no double talk

[sppmaster]

35 minutes ago, 2late4u said:

so if this all started right after your brake job at the dealership and have been back and the said they need to break in for a while ( which is bullshit) i would go back and demand they fix what they messed up on their dime ...be nice but be firm and dont stand for no double talk

I have been several times (5 or 6) at the dealer (two different FCA dealer service shops) for 10 months and they obviously cannot repair it and said it's OK and it's normal for this car that the brake pedal goes down to the floor (ridiculous and incompetent).

The worst thing is that I made an official complaint to the FCA customer care international hotline, I wrote several (over 10) emails to them explaining all of this in greatest details, asking them for official statement about the brake pedal movement and technical design and tolerances of the brake system, asking the support if all of this is normal and safe, complaining, etc.

I didn't receive any information, I've asked for. Not a single piece of technical data nor specification. 

Finally to my greatest regret I've been told this - Quote from the last email - "We are sorry to learn that you cannot accept the answer. Regrettably, we are not in the position to contest the information from our representatives."

What a joke.

Edited December 9, 2019 by sppmaster