Little backstory.... I commute a 4 lane highway (Hwy 17 in Northern California) that meanders through a 1300’ pass with a speed limit of 50mph, mostly pretty mellow left/right curves with a few hairpins. If you stick to the 50mph limit you’ll get run over by everyone else so it’s a pretty fast section of road.
I’ve been commuting this highway for the better part of 3 decades and always in a 4wd of some sort and when it’s wet out I would always put my trucks in 4 high during that part of my commute. Never had an issue and always made my vehicles stick to the curves and somewhat faster than the speed limit.
I came from a full-size super duty into my Ram, and today while commuting the hill I had the truck in auto 4wd because of a light rain and was traveling around 55mph uphill at a sustained speed around a gentle bend and the rear end started coming around on me.... scared the crap outta me and the truck of course reduced power and something on the dash yelled at me and with a little countersteer and reduced pedal input I was able to straighten out and continue without smacking the wall.
my old truck would have never done this ! I’ve driven this spot 1000’s of times in the same conditions at the same speed. I guess my questions are this ....
anyone else find the rear end too light and ever had any issue with the rear walking out on you? Anyone ever find the need to add some weight to the bed ?
should I forget about auto 4wd and just go for 4 high ? Maybe it didn’t engage fast enough to prevent this.
I have a hellwig in the garage that I haven’t installed yet, will that help this issue ?
Sorry for the silly questions but the manner that this occurred was so out of the norm from what I’m used to that I had to ask.... just not used to the rear end coming around like that And almost crashing my new truck. Thanks for any input.
I'm not sure what effect the non-factory tires would have on the various systems, but maybe the problem because of that is you
were in four-wheel drive: (Note items in
Green)
FROM 2019 DT Service Manual
NOTE: | The Electronic Stability Control (ESC) may also be referred to as Electronic Stability Program (ESP) depending on the vehicle model year and configuration. Certain components may also reference ESP, ESC, or use the traction control symbol. |
OPERATION
The ABS module is mounted to the Hydraulic Control Unit (HCU) together forming the ICU. The ABS module is a micro-controller based device which monitors the brake system during normal braking and controls it when the vehicle is in an ABS stop. The ABS function avoids wheel lock during braking maneuvers, maintaining the direction of the vehicle, and optimizing stopping distance.
The primary functions of the ABS are to:
- Monitor the ABS for proper operation.
- Detect wheel locking or wheel slipping tendencies by monitoring the speed of all four wheels of the vehicle.
- Control fluid modulation to the wheel brakes while the system is in an ABS mode.
- Store diagnostic information.
- Provide communication to the scan tool while in diagnostic mode.
- Illuminate the ABS, ESC, BRAKE, or EPB warning indicator lamp when the system is faulted.
- Illuminate ESC or EPB function lamp when a vehicle dynamic event is occurring.
- Illuminate the electric park brake warning lamp when a malfunction is present.
- Provide vehicle speed information, by monitoring the wheel speed sensors, to all modules on the Controller Area Network-Chassis (CAN-C) bus.
The ABS module constantly monitors the ABS for proper operation. If the ABS module detects a fault, it will turn on a warning indicator lamp and disable the ABS. The normal base braking system will remain operational.
NOTE: | If the vehicle is equipped with traction control, the ESC function lamp will illuminate anytime the amber ABS warning indicator lamp illuminates. |
The ABS module continuously monitors the speed of each wheel through the signals generated by the wheel speed sensors to determine if any wheel is beginning to lock. When a wheel locking tendency is detected, the ABS module commands the solenoids to actuate. The solenoids then open and close the valves in the HCU that modulate brake fluid pressure in some or all of the hydraulic circuits. The ABS module continues to control pressure in individual hydraulic circuits until a locking tendency is no longer present. The ABS module contains a self-diagnostic program that monitors the ABS for system faults. When a fault is detected, a warning indicator lamp is turned on and a Diagnostic Trouble Code (DTC) fault is then stored in a diagnostic program memory. A latched fault will disable certain system functionality for the current ignition cycle. An unlatched fault will disable certain system functionality until the fault condition disappears. These DTCs will remain in the ABS module memory even after the ignition has been turned off. The DTCs can be read and cleared from the ABS module memory by a technician using a scan tool. If not cleared with a scan tool, the fault occurrence and DTC will be automatically cleared from the ABS module memory after the identical fault has not been seen during the next 100 ignition cycles. Drive-off may be required for the ABS or ESC warning indicator lamp to go out on the next ignition cycle. Drive-off may be required for the amber ABS warning indicator lamp to go out on the next ignition cycle.
The ABS has multiple subsystems including, but not limited to, Traction Control System (TCS), Brake Assist System (BAS), Electronic Stability Control (ESC), Hill Start Assist (HSA), Electronic Roll Mitigation (ERM), Trailer Sway Control (TSC), and Hill Descent Control (HDC), Cornering Brake Control (CBC), Drag Torque Control [Motor Schleppmomenten Regelung] (MSR), and Off-Road ABS (ORA) ESC. All of these systems work together to enhance vehicle stability and control in various driving conditions.
A brief explanation of each subsystem follows:
TRACTION CONTROL
This system monitors the amount of wheel spin of each of the driven wheels. If wheel spin is detected, brake pressure is applied to the slipping wheel(s) to provide enhanced acceleration and stability.
BRAKE ASSIST SYSTEM
The BAS is designed to optimize the vehicle’s braking capability during emergency braking maneuvers. The system detects an emergency braking situation by sensing the rate and amount of brake application and then applies optimum pressure to the brakes.
ELECTRONIC STABILITY CONTROL
The ESC system enhances directional control and stability of the vehicle using steering wheel angle, yaw (turning) rate and lateral acceleration sensors (combined into Dynamics Sensor). Using signals from these sensors, in addition to individual wheel speed sensor signals the ESC corrects for over/under steering of the vehicle by applying the brake of the appropriate wheel to assist in counteracting an over/under steer condition. Engine power may also be reduced to help the vehicle maintain the desired path. Certain components may also reference ESP, ESC, or use the traction control symbol.
HILL START ASSIST
NOTE: | The HSA system does not operate on an automatic transmission vehicle in the neutral position. |
The HSA system is designed to maintain the level of brake pressure for a short period of time after the brake pedal is released so that the vehicle does not roll on a hill between releasing the brake pedal and applying the accelerator pedal. The following must be true for HSA to activate:
- The vehicle must be stopped with the brake applied
- The vehicle must be at a eight percent or greater incline (three percent for manual transmissions)
- Gear selection must match uphill direction (forward gear for uphill, reverse for backing uphill)
ELECTRONIC ROLL MITIGATION
The ERM system monitors steering wheel input and the speed of the vehicle. When the rate of change of the steering wheel angle and vehicle’s speed are sufficient to potentially cause wheel lift, the appropriate brake will apply and engine power may be reduced to lessen the chance that wheel lift will occur. ERM will only intervene during very severe or evasive driving maneuvers.
TRAILER SWAY CONTROL
The TSC system uses sensors in the vehicle to recognize an excessively swaying trailer and will take the appropriate actions to attempt to stop the sway. The system may reduce engine power and apply the brake of the appropriate wheel(s) to counteract the sway of the trailer. TSC will become active automatically once an excessively swaying trailer is recognized.
HILL DESCENT CONTROL
The HDC system maintains vehicle speed while descending hills in off-road driving conditions by applying the brakes when necessary. HDC can only be enabled when the transfer case is in the “4WD LOW” position and the vehicle speed is less then 48 km/h (30 mph). If these conditions are not met while attempting to use the HDC feature, the HDC indicator light will flash on/off. The HDC indicator lamp will be on solid when HDC is enabled. When enabled, HDC senses the terrain and activates when the vehicle is descending a hill. HDC is only intended for low speed off-road driving. The accelerator pedal will override HDC at any time.
CORNERING BRAKE CONTROL
The CBC function reduces the over steer tendency of the vehicle during an ABS braking maneuver in a curve by providing an anti-yaw moment through reduction of front inner wheel pressure. CBC is active during braking in curve maneuvers or when ABS function is active. CBC is not active when ABS function is not active. The ABS module will also monitor torque steering disturbance during CBC activation.
DRAG TORQUE CONTROL [MOTOR SCHLEPPMOMENTEN REGELUNG]
The MSR function tries to avoid locking of the driving axle during throttle-off maneuvers due to engine braking torque. MSR is active during throttle-off maneuvers. MSR activates when the locking tendency of a driving wheel exceeds the target value.
OFF-ROAD ABS (ORA) ESC
On deformable surfaces (gravel, sand, etc), a specific ORA calibration with higher wheel slip targets may be used to improve the ABS stopping distance. A larger wheel slip will help take advantage of the wedge effect of the deformable surface in front of the tires. ORA shall be automatically enabled if the vehicle has terrain switch setting(s) for deformable surfaces, or it may be enabled if the transfer case is switched to low range. The ORA logic may also be used if the ESC detects a deformable surface based on information from the wheel speed sensors, longitudinal acceleration sensor, and brake torque model. The larger wheel slip specifications used in ORA are dependent on vehicle speed, steering wheel angle, and surface roughness estimation. The ORA logic is not intended to be used on dry or wet asphalt, packed snow, or ice.
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Regards,
Dusty
2019 Ram 1500 Billet Silver Laramie Quad Cab 2WD, 5.7 Hemi, 8HP75, 3.21 axle, 33 gallon fuel tank, factory dual exhaust, 18” wheels. Build date: 17 July 2018. Now at: 031227 miles.