Inertia Switch Explained Removed and Replaced 1998-2012 Ford Ranger

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In this video, we're going to be working with our 2001 Ford Ranger, but we're going to be talking to you about a very generic and common problem on Ford, Lincoln and Mercury vehicles.

Today we'll be talking about your inertia switch. This is designed to trip in the event of a collision with the vehicle, shutting off the fuel pump relay and preventing fuel flow from coming out of the vehicle. This is designed as a safety feature, so if your vehicle is ever in a collision which causes a fire, it won't literally fuel that fire by pumping more gas out of the tank.

However, these switches do tend to be troublesome. They're known to go off for bad suspension, shopping carts hitting vehicles, and other situations that create just the right vibration to set these off and prevent your vehicle from starting or, in certain cases like having a bad strut or shock that creates a jarring vibration when going over a big bump, the vehicle can even shut down while running. Fortunately, this is very simple to check and correct, and we're going to show you how.

The inertia switch on this particular truck is located up against the firewall on the passenger floor, right above where your passenger's right toes would be. At the very top here is a little red button. When you push it down, you'll see the red bar here, indicating that the switch is down and allowing the fuel pump to turn on. If this switch is popped up, you won't see the indicator inside of this window, and you'll feel it flush at the top here. This means that it's been tripped by something. Either something running into the side of the vehicle, maybe your vehicle was bumped while parked or hit with a shopping cart or something similar, or maybe you hit a hard bump and tripped it. Pushing it down will restore operation to the fuel pump and allow your vehicle to start normally again.

Now, fortunately it's easy to reset that switch, but you may still have an underlying issue, like a bad shock or strut or another suspension component like a bushing creating that jarring vibration that's causing this switch to trip. If you go through and everything seems normal and it seems like the switch is resetting itself too easily, you may have to change it out, and this is how.

Fold down the carpet where the inertia switch is, and remove the connector with the help of a flat blade screwdriver. Remove the two five and a half millimeter screws securing the switch to the firewall with a socket, ratchet and extension. Then remove your inertia switch from the vehicle.

Install the switch back onto the firewall, and start your two five and a half millimeter screws by hand. Then tighten the screws down with your socket and ratchet. Reconnect the electrical connector. Push your carpet back into place and you're good to go.

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