Where is ignition switch harness located

OK, now that you know about the ignition switch and the wiring harness, you should understand their roles. As I said earlier, I consider the ignition switch to be the gatekeeper. A controller is considered anything that controls or governs the operation of an accessory—be it a simple switch or an on-board computer.

Switches are the simplest of all controllers. Most are manual, meaning that the operator of the vehicle has to operate them manually, such as a turn signal switch.

Switches are typically used to control low- to medium-current accessories. Higher current switches are sometimes used for high-powered accessories, such as headlights or fog lights.

When using a switch of any kind, it is important to match its current rating to that of the accessory it is controlling—a little bigger is never a bad idea.

As its name implies, it has a single pole common and a single electrical path that can be thrown open or closed. These switches are available in toggles, pushbutton, momentary, and many other styles. In the on position, the switch allows current to flow from the pole to the accessory. In the off position, the switch interrupts the flow of current to the accessory. These switches are easily identified, as they have only two electrical terminals. This switch is simple in concept, but incredibly versatile as it can be used in a great many arrangements.

All of the switches here are of the S. This third terminal is simply a ground input for the light. It is built into the toggle itself that goes on when the switch is closed. Of special interest is the push-button switch on the right.

Press the button once and the switch is thrown one way, press it again and the switch is thrown the other. In the center position, the C is not connected to anything.

In the up position, the C is connected to one of the N. A switch like this Figure is what automakers use to control the turn signals. By adding a simple diode to the switch, the up position allows the parking lights only to be on, and the down position allows both the headlights and the parking lights to be on—clever. The rheostat is built into the light switch assembly, which is used to dim the dash lights in my Mustang.

Look closely for the white ceramic part with the spring nearby; this is the rheostat itself. Rheostats: A rheostat Figure is a switch that allows one to vary how much voltage is applied to an accessory. In addition, a rheostat is typically designed to allow the passage of a considerable amount of current.

The dimmer switch controller for your dash lights is one such example. A rheostat is really nothing more than a variable resistor. It has a wiper that rides along a carbon contact surface that has a varying level of resistance, which is linear by design. This allows the switch to have any voltage between 0 VDC and 12 VDC available at its output, based on where the dial is manually set. Current Ratings: Most switches have a specified current rating.

This is the amount of current that the switch can safely pass through its contacts. In fact, OEMs typically use a switch with a higher current rating than the load connected to it, so that the switch provides many years of service. In addition, this can be a fire hazard. As I said earlier, this is my absolute favorite switch.

A relay Figure is simply an electromagnetic switch, so you already know what it does. The difference between a simple switch and a relay is how the switching is done. Relays are available in all shapes and sizes. Shown are S. Unlocking the Mystery: OK, so why are relays typically regarded as black magic? Since you already know all about switches, the relay is simply an extension of that knowledge. No different than switches, relays are also available in many different variations.

This means that a relay really has two electrically isolated parts:. They can have four or five terminals. Even though they may look similar from the bottom, not all five terminal S.

I believe that this is where some of the confusion begins. After all, the five terminal S. T and the S. Diagram illustrates the differences between the four most commonly used automotive relays. How do you know for sure what kind of relay you have or need to purchase when looking at them in the store? Easy—the body of the relay itself typically has an electrical diagram embossed or stamped on it; this is called the legend, and it is similar to the diagrams in Figure , allowing you to determine which relay you need.

Only S. Five-terminal S. The legends on the housings of this S. This means that you can-not use one of these in a circuit that calls for the other. To power the coil of a relay, voltage needs to be applied across terminals 85 and That being said, some relays have built in quenching diodes see the sidebar on diodes for an explanation so polarity must be observed with these. The coil is powered to establish an electrical connection between the common and normally open terminals.

Note the electrical difference in the two five-terminal S. Terminal 30 is labeled, but is just above the terminal on the left and out of the shot. This same relay has the electrical diagram screened on the side of the body itself. Obviously, this is an S. Although the Bosch relay looks identical to its S. See, I told you relays were simple.

No different than an S. The next chapter explains how to use them in your own projects. Current Ratings: No different than switches, relays have current ratings as well.

The current rating of a relay is the amount of current that can safely pass through the contacts and has nothing to do with the current the coil requires. A amp relay does not require 30 amps of current to power it up. Rather, that means that the relay can power an accessory requiring up to 30 amps of current. Again, the OEMs choose to use higher current relays than necessary so that they last a long time. There are different grades of relays.

Of course you know that I have a personal preference, and that has been the Bosch-branded relays. Most of the relays in my Olds are located here. I made the mounting point for them from very thick strapping material and screwed that to the firewall.

For each mounting point, I mounted a bolt to the strap. A single nut holds the relays in place for easy serviceability. The underhood fuse box in the Nissan Frontier truck houses relays, fusible links, and fuses for those accessories that are tied to the battery directly. The box is located directly behind the battery. This is your basic Ford starting solenoid.

The two silver terminals are for the coil, while the two copper terminals are the connections to the switch itself. The solenoid on the left is rated for 80 amps, and the one on the right is amps. Both are continuous duty ratings. The terminal configurations are identical to the Ford solenoid.

The heavy-duty flasher in the middle is from Tridon and is rated for up to 25 amps of current. The current required to properly power the accessory determines which relay to choose and install.

Using a amp relay to power a amp accessory causes its contacts to fail prematurely because they become pitted. In addition, a relay should always be mounted with its terminals pointing down to avoid the possibility of water entering its case. Relay Centers: Most vehicles have a central location for all of the relays used for the high current accessories. Depending on the vehicle, this can be under the dash or under the hood.

In my Olds, I made my own relay center by locating all the relays on the firewall just above the transmission hump. This was done for serviceability because I know all the relays in the vehicle except one are in this location.

You should make a point to know if your vehicle has a relay center and more importantly where it is. Chapter 5 offers gives several scenarios of how to use relays in your own projects. Now that you know all about relays, you know about switching solenoids.

Solenoids are used to do all kinds of things—electrical and non-electrical. An electrical automotive switching solenoid is really nothing more than a very high current relay. Another example is the high-current aftermarket units shown. These are used for any number of things. More on this in Chapter 7. Sometimes the case of the solenoid itself can be the negative connection to the coil.

If so, it needs to be solidly mounted to a clean metal surface. When voltage is applied to the trigger terminal, its contacts close, thereby making the high-current electrical connection between the battery and load terminals. Flashers are typically found in the fuse panel and used in the turn signal and hazard circuits. Typically called LX flashers, they have two terminals only. One terminal connects to power, the other to the load. As current flows through the flasher to the load, it has an element within it that is designed to break the electrical connection briefly and then restore it.

Flashers are connected to the power input lead for the turn signal and hazard circuits. As the output of both to those circuits is typically directed to the same filaments of the same bulbs, one flasher is required for the turn signal switch power input and a second for the hazard switch power input.

The Fuse Panel: In a given auto-mobile, you have at least one central fuse panel. Most vehicles nowadays have one fuse panel under the dash and one under the hood. The underhood panel typically contains the fuses for the high current up to A accessories and the main power to the ignition switch.

The under dash panel typically contains all of the fusing and breakers for the vehicles lower current accessories—such as the radio, cigarette lighter, power windows, etc. Victor Fortunato Automotive Mechanic. The statements expressed above are only for informational purposes and should be independently verified.

Please see our terms of service for more details. Home Questions. Experienced Mechanic? Apply Now. The blend door failure can cause your temperature control Read more. What does the Door Ajar light mean on the dash? Your car is equipped with a number of different sensors to help ensure that you and your passengers stay as safe as possible. The Door Ajar light on the dash turns on automatically when you crank the car, but should I would first verify that the vehicle has a drain above milliamps by disconnecting the battery's negative cable and putting an amp tester between the post and clamp.

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Car idling roughly and jerking, check engine light came on Quite a few items can cause a misfire condition in your vehicle. Usually worn spark plugs are the most common cause, so they are usually replaced first before diagnosis can proceed any further. Since yours have been replaced as well Car stalls, P code Hello.

Most of the time this is caused by one of two things on your vehicle. It is either because the powertrain control module, or engine computer, is failing internally, or the main relay that supplies power to it is On CNG, engine often give a sound of misfiring and got stop, while on petrol no such issue Hello.