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Nelson

Soft brake pedal, bad ABS unit?

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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!

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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

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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. 

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

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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.

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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.

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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. 

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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.  

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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!

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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 

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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 by sppmaster

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