Pulling to left when braking intermittently - 2014 ram 3500

[Bestt959]

Having a hard time finding any information on my exact issue. Here is the situation:

I recently replaced my HUC (hydraulic control unit) as mine was faulty. Everything now works as it should but shortly after I noticed sometimes when braking the pedal would feel hard and I get a hard pull to the left. It only happens about 20% of the time I’m braking and it comes and goes with no rhyme or reason.

I removed my caliper and inspected the slides/pads/shoes/brake piston operation and everything seems fine. I also bled the brake line to make sure my line isn’t collapsed.

My questions are
do caliper intermittently fail?
Is this an issue a faulty HUC could cause?
Has anyone went through this before?

I don’t want to buy a new caliper if I can’t tell if mine is junk or not.

Let me know what you think

 

[Bike_Pilot]

I've had calipers intermittently stick on, but never had one fail to brake. There is so much pressure in the braking system I can't iiit could intermittently fail to actuate under that sort of pressure.

Is the pedal feel different when it pulls than the other 80% of the time?

 

[Bestt959]

Yes it is much harder to push when it pulls. It feels normal most the time and the braking works as it should until randomly it’s hard to press the brake and it pulls hard

 

[Bike_Pilot]

Gotcha. I would think it would be an issue with the abs system most likely.

 

[mtofell]

Just a thought.... which caliper did you check? If it's pulling left could that mean the right isn't engaging?

 

[Sherman Bird]

Having a hard time finding any information on my exact issue. Here is the situation:

I recently replaced my HUC (hydraulic control unit) as mine was faulty. Everything now works as it should but shortly after I noticed sometimes when braking the pedal would feel hard and I get a hard pull to the left. It only happens about 20% of the time I’m braking and it comes and goes with no rhyme or reason.

I removed my caliper and inspected the slides/pads/shoes/brake piston operation and everything seems fine. I also bled the brake line to make sure my line isn’t collapsed.

My questions are
do caliper intermittently fail?
Is this an issue a faulty HUC could cause?
Has anyone went through this before?

I don’t want to buy a new caliper if I can’t tell if mine is junk or not.

Let me know what you think

The giveaway is herd effort during failure. You most likely have a defective hydraulic unit. It's also possible that you need to properly power bleed the system AND take the truck out and exercise the unit.... this is where you find an isolated place to "Cram" your brakes on to the point of forcing the ABS to cycle. If, after several induced ABS cycles, the problem lets up, you need a new HCU.

Other possibilities further down the list would include a flex hose intermittently restricting flow from inside due to internal swelling of the hose. THAT failure is usually one which causes a hard pull but only for a second, then the brakes don't pull during the remaining slow down.

My professional advantage is that I own those uber-expensive pressure gauges that go into the bleeder ports, thus getting accurate readings... and their expense make them impractical to buy for the layperson.

One question I have is if you pulled codes for the ABS system. If so, share, please!

 

[Bestt959]

No codes for the abs system just checked.
The pedal doesn’t get hard hard it just stiffens a little bit and doesn’t press fully. I’m starting to lean towards faulty HCU but I’m not entirely sure what would be wrong with it. Haven’t pulled a single code so must be some sort of mechanical valve failure?

I only inspected the front left brake system I can’t see the right side having anything to do with it but may be worth a look. It feels almost as if only the front left brake is engaging when it is failing

 

[Bestt959]

The giveaway is herd effort during failure. You most likely have a defective hydraulic unit. It's also possible that you need to properly power bleed the system AND take the truck out and exercise the unit.... this is where you find an isolated place to "Cram" your brakes on to the point of forcing the ABS to cycle. If, after several induced ABS cycles, the problem lets up, you need a new HCU.

Other possibilities further down the list would include a flex hose intermittently restricting flow from inside due to internal swelling of the hose. THAT failure is usually one which causes a hard pull but only for a second, then the brakes don't pull during the remaining slow down.

My professional advantage is that I own those uber-expensive pressure gauges that go into the bleeder ports, thus getting accurate readings... and their expense make them impractical to buy for the layperson.

One question I have is if you pulled codes for the ABS system. If so, share, please!

I may try and force the Abs system to kick in a few times on a gravel road or something and see if there’s any change like you said

 

[Sherman Bird]

No codes for the abs system just checked.
The pedal doesn’t get hard hard it just stiffens a little bit and doesn’t press fully. I’m starting to lean towards faulty HCU but I’m not entirely sure what would be wrong with it. Haven’t pulled a single code so must be some sort of mechanical valve failure?

I only inspected the front left brake system I can’t see the right side having anything to do with it but may be worth a look. It feels almost as if only the front left brake is engaging when it is failing

Get a scanner.... go to the ABS module selection.... select LIVE DATA.... drive the truck slowly accelerating and observe the wheel speed(s) and ensure they all show the same increase in speed. (they probably do.)

 

[Bestt959]

Get a scanner.... go to the ABS module selection.... select LIVE DATA.... drive the truck slowly accelerating and observe the wheel speed(s) and ensure they all show the same increase in speed. (they probably do.)

They do yes

 

[Sherman Bird]

They do yes

When my wife's HCU failed, it was in a BIG way. Her car is a 2007 KIA Sorento with 233,000 miles on it. At 203,000 I bought the car very cheap, in large part due to the ABS unit being bad. At that time, the replacement part from KIA bottom lie was a tad over 2 grand.

The symptoms were that the car pulled VERY hard to one side; enough that I had to REALLY steer hard in the opposite direction to stay in my lane.... Also, it was as if I were trying to crush a cinder block with my leg to stop the car, in terms of a VERY VERY hard pedal. When I'd release the brakes, the sudden release of pull would cause the car to pull violently the other way into either the other lane, or ditch, etc. It was absolutely hazardous to drive. Diagnosis showed that I had plenty of master cylinder pressure going INTO the HCU, bot only 2 outlet ports giving pressure to one front wheel, and diagonally only one rear brake.

Due to the insane cost of the replacement part, I took the HUGE risk and bought a salvage unit, coded it to the car, and got EXTREMELY lucky in that it has been fixed nigh on 4 years.

IF this had been any body else's car, they would have been quoted for the new part and labor, due to liability issues.

It's next to impossible for ANYONE here on this forum to diagnose your problem with any degree of certainty. Inasmuch as it could be life or death, I'd strongly urge you to take the truck to a professional.

 

[Bestt959]

When my wife's HCU failed, it was in a BIG way. Her car is a 2007 KIA Sorento with 233,000 miles on it. At 203,000 I bought the car very cheap, in large part due to the ABS unit being bad. At that time, the replacement part from KIA bottom lie was a tad over 2 grand.

The symptoms were that the car pulled VERY hard to one side; enough that I had to REALLY steer hard in the opposite direction to stay in my lane.... Also, it was as if I were trying to crush a cinder block with my leg to stop the car, in terms of a VERY VERY hard pedal. When I'd release the brakes, the sudden release of pull would cause the car to pull violently the other way into either the other lane, or ditch, etc. It was absolutely hazardous to drive. Diagnosis showed that I had plenty of master cylinder pressure going INTO the HCU, bot only 2 outlet ports giving pressure to one front wheel, and diagonally only one rear brake.

Due to the insane cost of the replacement part, I took the HUGE risk and bought a salvage unit, coded it to the car, and got EXTREMELY lucky in that it has been fixed nigh on 4 years.

IF this had been any body else's car, they would have been quoted for the new part and labor, due to liability issues.

It's next to impossible for ANYONE here on this forum to diagnose your problem with any degree of certainty. Inasmuch as it could be life or death, I'd strongly urge you to take the truck to a professional.

My HCU did fail and then I did exactly what you did and bought a salvaged unit and programmed it into my truck. Then a completely different problem began happening. My take away is I was sold a bad HCU

 

[Sherman Bird]

My HCU did fail and then I did exactly what you did and bought a salvaged unit and programmed it into my truck. Then a completely different problem began happening. My take away is I was sold a bad HCU

I recently bought an ABS complete unit (salvage) for my 2002 S/T Blazer. It was bad, and I got a refund. Replacement parts for the Chevy are WAY cheaper than that of the Kia..... but it's still more than I want to pay.