ABS/Traction Control?

[1970FuryConv]

The passenger rear brake caliper on my wife's 2011 Dodge Nitro jammed and began heating up my wheel because the piston could not retract. I followed the factory caliper replacement procedure, including using a piece of wood to hold the brake pedal down so that the master cylinder did not empty. I bled the passenger side rear brake caliper, using single pumps of the brake pedal and a 10 mm wrench to crack it during pumping FSM 5-7. I bled it until no air was coming out of the bleeder valve. I then manually bled all 4 brakes. Again no bubbles

Problem: After changing the caliper, braking is usually normal. However, if I hit a big bump at medium speed or if I spin a tire in rain, the ABS system takes away my part of my brakes and the pedal falls halfway to the floor. I have to pump the pedal furiously to get my brakes back. No warning lights light in dash.

My questions are:

Did I damage the wheel speed sensor but set no code?

Do I have to have the brakes pressure bled by a shop because its ABS?

Or does the ABS unit need to be reprogrammed back to its default settings?

BTW: I posted this question on a Nitro forum. Got no answers.

 

[odcics2]

Try posting on Allpar. A lot of talent there and they appear to have experts on all MoPars.

 

[mopar440]

Lots of times, you have a bleed process that involves running the pump with a scan tool, does it mention that?

 

[1970FuryConv]

Lots of times, you have a bleed process that involves running the pump with a scan tool, does it mention that?

No, but it is a 2008 FSM and the truck is 2011.
2008 was the last year for factory shop manuals for my truck.

 

[1970FuryConv]

Try posting on Allpar. A lot of talent there and they appear to have experts on all MoPars.

Posted to Allpar.
Does not look like many people use that forum. Hope I get an answer. Nothing ventured, Nothing gained.

 

[65sporty]

I bleed calipers all the time by just pumping the pedal, very rarely do I have to bleed with the scan tool. I am assuming the ABS light is off? When you loose brake pedal do you here the ABS pump running? Do you have access to a scan tool to check for codes?

 

[mopar440]

Id guess there has to be air in the abs unit. Either run it with a scan tool, or get it to activate on gravel, then bleed all wheels. Repeat 2-3 times if needed

 

[BigblueC]

get it to activate on gravel, then bleed all wheels. Repeat 2-3 times if needed

I've never had to work on an ABS unit so I'm curious. How does getting it to activate work out an air bubble in a way that it can then be removed via standard bleeding?

 

[mopar440]

I've never had to work on an ABS unit so I'm curious. How does getting it to activate work out an air bubble in a way that it can then be removed via standard bleeding?

There are valves that are actuated by solenoids when abs is applied. They don't move otherwise. Air gets up to the valve, and them gets trapped. Could have a bad abs unit, but doubtful

 

[1970FuryConv]

I bleed calipers all the time by just pumping the pedal, very rarely do I have to bleed with the scan tool. I am assuming the ABS light is off? When you loose brake pedal do you here the ABS pump running? Do you have access to a scan tool to check for codes?

ABS light is off and has never come on in 70000 miles of ownership, except at start up when it is a test light.
I do not hear the ABS pump running when I lose brake pedal.
I don't have a scan tool that works with 2011 trucks. It works with earlier models. Would there be codes with no warning light? thanks, Ben

 

[1970FuryConv]

Id guess there has to be air in the abs unit. Either run it with a scan tool, or get it to activate on gravel, then bleed all wheels. Repeat 2-3 times if needed

I don’t know how to bleed the brakes with the ABS unit activated. Does that require the scan tool or a DRB type tool to keep the ABS unit activated?

I was careful to block the pedal forward per the factory shop manual’s instructions. I was careful not to pump up the brake pedal but the pump it once with the valve open and close the valve before letting the pedal (operated by an assistant) be released. I have a one-man bleeder kit and I did 4 bottles through the right rear caliper, then another bottle at each of the other 3 calipers. I don’t see how air could have gotten up to the ABS unit, but anything is possible. If Air in the system is the problem, it sounds like it would be simpler for me to pay a shop to pressure bleed the system, then for me to continue to f with it.

On Allpar, one of the members commented that when I replaced the caliper and the caliper mount, I may have damaged the wheel speed sensor connector, such that the system is losing contact when I hit these bumps and the result is that the ABS unit disables the rear brakes because it thinks I have no traction at those wheels. What do you think of his theory?

Thanks, Ben

 

[rapidtrans]

The damaged sensor is reasonable. Wait awhile as there are a lot of good mechanics on Allpar. I’ve quit reading the site as their software conflicts with my VPN. I ain’t turning it off just to read what “voice of steel” is complaining about lately!

 

[3C's & a D?]

On Allpar, one of the members commented that when I replaced the caliper and the caliper mount, I may have damaged the wheel speed sensor connector, such that the system is losing contact when I hit these bumps and the result is that the ABS unit disables the rear brakes because it thinks I have no traction at those wheels. What do you think of his theory?

That's possible, but I don't think that's it. I've been fighting with a front wheel speed sensor for awhile on my '06 Magnum. My red circle light has been on for months, however cruise works, and there has never been any loss of braking power. I would think if you're speed sensor was a problem, a warning light on the dash would let you know. Did you notice any lights, or audible dings when experiencing the problem?

Possibly a bad caliper? Since the problem occurs with wheel spin, just to see, I would turn esp off and induce wheel spin. I'm not sure what that would tell you, it's a variable though.

 

[mopar440]

I don’t know how to bleed the brakes with the ABS unit activated. Does that require the scan tool or a DRB type tool to keep the ABS unit activated?

I was careful to block the pedal forward per the factory shop manual’s instructions. I was careful not to pump up the brake pedal but the pump it once with the valve open and close the valve before letting the pedal (operated by an assistant) be released. I have a one-man bleeder kit and I did 4 bottles through the right rear caliper, then another bottle at each of the other 3 calipers. I don’t see how air could have gotten up to the ABS unit, but anything is possible. If Air in the system is the problem, it sounds like it would be simpler for me to pay a shop to pressure bleed the system, then for me to continue to f with it.

On Allpar, one of the members commented that when I replaced the caliper and the caliper mount, I may have damaged the wheel speed sensor connector, such that the system is losing contact when I hit these bumps and the result is that the ABS unit disables the rear brakes because it thinks I have no traction at those wheels. What do you think of his theory?

Thanks, Ben

It's just been my experience that air slips in there, especially on newer silverados, those are a nightmare

Take it out to some loose safe gravel, dnr get it to kick on, then re bleed. Or take it in, that's your choice

 

[70bigblockdodge]

It might be the master cylinder. If it was a sensor the light would be on, they are pretty sensitive.
Abs works against the master cylinder, except on traction control. I would think the ABS light would trigger is pressure is dropped by the master cylinder but maybe not.
If you have air in the ABS unit it will act as if you have air anywhere else, mushy pedal.

 

[65sporty]

Usually you get a light with codes, any time I have had a speed sensor drop out you get unwanted ABS and will hear the pump run. Can you get it to act up at will or is it random? You may have to take it in and have it checked with a scan tool.

 

[1970FuryConv]

It's just been my experience that air slips in there, especially on newer silverados, those are a nightmare

Take it out to some loose safe gravel, dnr get it to kick on, then re bleed. Or take it in, that's your choice

dnr usually means, does not run. I guess you mean spin a wheel in gravel?

Usually you get a light with codes, any time I have had a speed sensor drop out you get unwanted ABS and will hear the pump run. Can you get it to act up at will or is it random? You may have to take it in and have it checked with a scan tool.

So far, it's been random. No lights, just hit a bump too hard or lose traction and sometimes it happens

 

[1970FuryConv]

That's possible, but I don't think that's it. I've been fighting with a front wheel speed sensor for awhile on my '06 Magnum. My red circle light has been on for months, however cruise works, and there has never been any loss of braking power. I would think if you're speed sensor was a problem, a warning light on the dash would let you know. Did you notice any lights, or audible dings when experiencing the problem?

Possibly a bad caliper? Since the problem occurs with wheel spin, just to see, I would turn esp off and induce wheel spin. I'm not sure what that would tell you, it's a variable though.

NO LIGHTS OR DINGS. Wheel is not heating up, no uneven pad wear. I could try spinning a wheel with ESP off/on to see if induces problem.

It might be the master cylinder. If it was a sensor the light would be on, they are pretty sensitive.
Abs works against the master cylinder, except on traction control. I would think the ABS light would trigger is pressure is dropped by the master cylinder but maybe not.
If you have air in the ABS unit it will act as if you have air anywhere else, mushy pedal.

Pedal is not mushy. Brakes work fine vast majority of the time.

 

[PH27L7]

The fact that your caliper piston froze indicates the system had water in it and it rusted. That indicates the brake fluid has not been flushed on a regular basis and your whole system could be crusty including your master cylinder.

The brake pedal dropping & you pumping it to get the brakes back is classic bad MC. When you pushed the pedal to the floor you could have disturbed the rust in the MC or even introduced crud into the ABS unit. This is unnecessary, all you need to do is plug the line where you are replacing the caliper to prevent fluid loss.

As long as you did not drain the MC there should be no air introduced to the system. You need to get a scan tool to diagnose the ABS, otherwise you are guessing. If if there is no current light it will tell you where the problem is historically. I couldn't find a free scanner at the auto parts store that did anything other than engine codes so I bought an Innova 5510 which is amazing for the price. For something like $200 with discounts from Advance it does all kinds of things including ABS troubleshooting & ABS bleed activation.

 

[mopar440]

dnr usually means, does not run. I guess you mean spin a wheel in gravel?



So far, it's been random. No lights, just hit a bump too hard or lose traction and sometimes it happens

Don't know why I typed dnr... Yes, meant activate them on gravel, getting a scan tool is better tho