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SMI Stay-IN-Play DUO Braking System Review

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Review of the SMI Stay-IN-Play DUO Braking System

Today we're going to be taking a look at the SMI Stay In Play Duo Supplemental Braking System, part number SM99251. This is an automatic proportional braking system that never has to be removed, replaced, or reset. The duo will activate when the RV or tow vehicle brakes are on. There's a switch in the car that detects braking. With the sensitivity controlinertia sensor set inside the vehicle, you can adjust more or less braking, depending on the weight of the vehicle. Let's go over our components for the Stay in Play duo system.

This is the control unit. It also has a vacuum pump built inside. The control unit, we get wired to the break-away switch in the operating unit. The long, black hose that comes out of it is for vacuum assist that will connect to the vehicle's vacuum, typically in front of the brake booster. Provided with the install kit will be the necessary adapters, check valve, and air line T to connect the vacuum assisted hose. The control unit here, has the built-in inertia switch and the on-off switch that will get set inside the vehicle; the label here will face the passenger's side, so that the inertia switch is set in the proper position.

It will connect to the operating unit in the vehicle's tow wiring. Another important component here of the Stay in Play system is the break-away switch. The break-away switch is to act in emergency situations, and will automatically throw the braking system into full on, when the switch or pin is pulled out. This will get connected to the tow vehicle, in the case of a break-away or major emergency. Here, we have the actuator that will pull on the towed vehicle's braking pedal, to create the braking. This is an anchor point that will use a self-tapping screw to secure it to the firewall.

Built into it is a clamp and bracket setup that will go around the arm of our brake pedal. Connected to it to operate the actuator will be the hard plastic line that will connect to our vacuum pump from the operating unit. Here is our indicator light that will mount inside the towed vehicle, so that we know when the brake pedal is being depressed. Along with our install kit, we'll have the necessary quick-splice connectors, butt connectors, and ring terminals. Even a quick-splice tap to connect as necessary, and then cover our wires and secure them as necessary, as part of our install kit. Here's the SMI controller.

Again, we have the on-off switch. We'll flip it to on. The mounting location for each of these components will vary from vehicle to vehicle, but we have to make sure that our controller label is facing the passenger side. This application, we've mounted in the rear cargo area. Another good location would be the front kick pannel near the hood release. The operating unit for this vehicle, we've mounted inside and underneath the driver's front seat. We'll slide the seat forward; we'll get a better view of the box. You can also see the vacuum and air line that come out of the front. This will complete the review of the SmI Stay in Play Duo Supplemental Braking System, part number SM99251. .

Questions and Comments about this Video

Don M.


Etrailer Expert
Reply from Victoria B.

This SMI Stay IN Play DUO Braking System is a great option for your 2019 Wrangler. I have linked our fit guides for breaking systems, base plates, and wiring to flat tow your Wrangler.

Steven R.

After hooking up tow vehicle when i check blinking direction lights on the tow vehicle a noise from play box and the leds on the mirror flashes red. noise sounds like chattering relay?

Etrailer Expert
Reply from Jon G.

Just to double check, everything is working properly and you are just asking about the noise from the box with the switch on it?

Reply from Steven R.

@JonG Thanks for reply found instruction manual solved my problem.

Etrailer Expert
Reply from Jon G.

@StevenR Glad to hear it!

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