I've been chasing down some strange feedback at the brake pedal for a few weeks. All started after returning from a trip to Colorado, it rained epic amounts on the way there and back but they symptoms only surfaced after I made it home. Feels is very similar to ABS or when ATRAC activates but not nearly as aggressive. It mostly occurs with light breaking at 20 MPH or lower but can not be produced consistently. My first thought was a rotor with some run-out so I swapped all of the brake wear components, sadly no change. The speedometer also has occasional irregular behavior mostly above 60 MPH where the needle jumps around +/- 3 MPH. When this occurs cruise control is still available but no fun to use.
Dash Lights -
None of the typical trio lights are lit up. No ABS or a check engine either.
Had the truck scanned at O'Reilly's a couple times and it showed faults with both rear wheel speed sensors. All have been cleared with the reader but I suspect they will be back.
4 new rotors
4 new pads
4 brake sensors not new but from a working vehicle. Thanks
Cleaned sensors at all 4 corners and removed the grease from their mounting holes. Disconnected, cleaned and inspected wheel speed connectors and where the 2 rear meets the harness above the passenger spring. All were cleaned with QD contact cleaner spray. No breaks or obvious damage to the wires or connectors. Cleaned/Polished the plunger assembly in the brake accumulator.
Here is what we have done to "fix" it and where it gets weird.
***incorrect***Unplugged the black connector at the hydraulic brake booster and all symptoms are gone
but at the cost of no ATRAC (possibly more) and the brake indicator light is on. I believe this is the Skid Control Unit that is integrated? into the brake booster.
Has anyone seen this and know a solution? If it turns out to be the brake booster how difficult is the swap?