WHATS THE ROUND THING UNDER TRUCK, on the Frame on the passenger side front door ?

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dieseldave

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Does any one know what the 4inch round thing that is bolted to the frame under the passenger side front door Is ? It also has 2 electric wires to it
 

Daw14

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Tracking device ?
 
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dieseldave

dieseldave

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What does a vibration dampener do ? Why does it need 12 volt power ?
 

Dusty

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The correct component term is Active Vibration Control Actuator (AVCA) and is controlled by an electronic module. Each contains an internal impulse magnet. There are two, one mounted on each side of the vehicle frame. The angle and location of each AVCA is critical.

Regards,
Dusty
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MJCs18Diesel

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Dusty, thanks for the reply. This is how we learn about our trucks. However, what is it for? What does the circuit sense or detect? And, then, what does it do? Does it detect the truck skidding into a potential 360 on icy roads as part of the ABS sway control circuit?
 

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funny thing is many of the 2022 trucks were missing them due to supply chain issues, so they must not be that important lol.
 

retired

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Dusty, thanks for the reply. This is how we learn about our trucks. However, what is it for? What does the circuit sense or detect? And, then, what does it do? Does it detect the truck skidding into a potential 360 on icy roads as part of the ABS sway control circuit?
they cancel out vibrations when mds kicks in ie tries to mask the rough running of only running on 4 cylinders, nothing to do with abs sway control
 

GTyankee

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That cylinder-deactivation mode, meanwhile, should be a little less noticeable on the 2019 truck. A pair of active dampers mounted on the frame rails vibrate counter-phase to the engine to help quell any shaking that would otherwise be noticed when the V8 runs on four cylinders.
 

Dusty

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Dusty, thanks for the reply. This is how we learn about our trucks. However, what is it for? What does the circuit sense or detect? And, then, what does it do? Does it detect the truck skidding into a potential 360 on icy roads as part of the ABS sway control circuit?
It is a system used to cancel resonant vibration frequencies generated by the engine when in the four cylinder mode (MDS). The Ram system is considered 'active' because it is not part of the passive motor mount. The Ram system contains two separate components: the mechanical Actuators (the "round" things) and a AV Control module.

The Actuator contains a rotating magnet that receives modulation current based on the amount of vibration detected. This rotating magnet offsets certain vibrations in what is determined to be the dominant vibration path. The placement of the actuators is strategic, in that engineers have determined the point in the frame that is most reactive to the vibrations from the engine. You will note that these are placed near the floor pan area just below the front seats. This is because it is the span of the frame rail from front-to-back that is most responsive to engine pulses.

So someone will ask why didn't the fourth gens which had MDS, have them? The answer is on 5th gens the approximate threshold engine RPM for entering MDS was lowered by about 150 RPM. This reduced engine speed in MDS intensified engine pulses.

Regards,
Dusty
2019 Ram 1500 Billet Silver Quad Cab 2WD, 5.7 Hemi, 8HP75, 3.21 axle, 33-gallon fuel tank, factory dual exhaust, 18” wheels. Build date: 3 June 2018. Now at 70140miles
 
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