ABS / Stability Control problem. 2010 Ram 1500

[PaulSwany]

I've read countless threads on here relating to ABS problems with the RAM 1500 truck. I don't wanna just throw parts at it, so I'm trying to find what to check.

My symptoms:
Stability Control light comes on intermittently with the front brakes locking up randomly.

What I've done so far:
I OHMed the speed controls and none of them checked out, so I replaced them all. No change.
Checked for voltage at the speed sensor plug. All had around 12 volts (battery voltage)
Read all the ABS codes and found one for steering angle, recalibrated it and that went away. Still no change with the locking brakes.

What else can be wrong? What else can I check?

 

[Jeepwalker]

Randomly ...as in even if you don't touch the pedal the fronts lock up?

Have you tried driving it with the module unhooked?

What's the process to get it to 'un-lockup'?

 

[62Blazer]

Does the stability light coming on and the brakes locking up always happen at the same time? Do both front brakes lock up, or only one side? When the stability control light comes on briefly, that often just means the system is active at that moment. For example, if you go out on the ice and accelerate hard to the point where the traction control/stability activates the lights on the dash will come on while it is active.

The question is if the stability control system is activating and causing the front brakes to engage, or if the brakes are engaging and the therefore the stability control is kicking on to counteract any sway or unusual vehicle handling that the brakes are causing.

To actually start diagnosing you need access to a good diagnostic scan tool that can read and record live data. Then drive the vehicle and when it acts up look and see if any of the signals look haywire. On a tool with this capability you select which channels are being viewed. I'm by no means an expert on the system, but would start with looking at wheel speed signals and the yaw sensor. The yaw sensor is the main component that tells the stability control system the vehicle is getting out of control and needs to activate. Basically is says if the vehicle has started sliding sideways or getting tippy.

 

[PaulSwany]

I have a cheepy scanner, can you suggest one that would show live data from each wheel?

 

[PaulSwany]

Anyone have experience with this scanner?

fit for Chrysler/Jeep/Dodge OBD2 Scanner All System Bidirectional Scan Tool Kit | eBay

Fit For example, if "Press Brake Pedal" displays, you have to press and hold the brake pedal and then continue. Fuel Injector Pump/ Fuel Trim Reset. -Steering Angle Reset : Reset the steering angle to zero to keep the car running straight.

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[ConorToot]

Would using the graphing feature on AlfaOBD be a good enough monitor to check the systems?
I have a couple dozed recordings of tests where the fault code (C121E) was cleared, the graphing feature turned on and set to record with the four wheel speed sensors, brake pressure, yaw and inertia device, and steering wheel angle sensor are recorded. After a few minutes of driving, the code will come up indicated by the MIL dash light. Each time, I've stopped the recording and reviewed what was recorded, but I see nothing that looks out of whack.
With the vague description provided for a C121E fault, ive been working on fixing this dumb problem for over a year because I was just looking over the logs that I've recorded dated a year and a month ago. This stupid fault code has been costly as I've thrown every part I can think of at it in my unsuccessful attempt to fix it.
So far, I've replaced:
- Both rear wheel speed sensors
- Both front wheel speed sensors
- One brake switch
- Both front brake calipers, disks, and lines with calipers that were equipped with steel pistons and disks designed for heat dissipation.
- Both rear calipers and disks with calipers that were equipped with steel pistons and disks designed for heat dissipation.
- Another brake switch
- Both front wheel hubs replaced with Timken bearings including the tone ring, and wheel speed sensors
- I've purchased for brake bleeding kits
- I've gone through six or seven quarts of brake fluid
- One more more brake switch for the hell of it
- The front brake pads due to wear.
- Four new tires.

These items were not part of diectly repairing the C121E fault, but were replaced, often upgraded, because they were worn out, broken, or benefitted the truck due to it passing 200k miles:
- Adjustable, heavy duty rear upper and lower control arms.
- Rear shock absorbers replaced with Rancho shock absorbers.
- Rear springs that lowered the back end by 3" so it rides level.
- Front shock absorbers with Rancho shocks .
- Front stabilizer arms,
- Frinont lower control arm ball joints with Precision brand ball joint, pre-installed into the control arrm into a heavy duty solid control arm.
- Front upper contril control arms were replaced with solid, forged steel, and heavy duty ones.
- Inner and outer tie rods.

I've bled brakes a dozen times or more. I've run every check or procedure I could think of including rebuilding the ABS control module.

Any fresh ideas are very welcome.