Learn All About Car Switches, Sensors & Relays

The “sensors” are basically coolant temperature sensors (CTS). They are interchangeable, also known as ECT/ECTS (engine coolant temperature sensor). They measure the temperature of the antifreeze/coolant in your vehicle's cooling system. This sensor works continuously and ensures the engine works at the right temperature.

Your vehicle has a cooling fan present, which pulls in air via the radiator and keeps the engine cool. The cooling fan relay controls the cooling fan. This relay is activated as needed so that the fans work. Usually it will be activated when the vehicle has reached a higher temperature than needed.

The switches perform the same functions as all other switches you may be knowing. They allow functionality of every part in your vehicle. Some of these require higher current capacity, while others don’t. The low voltage switches typically will control the electrical position of a relay. This directs a higher current so that they can be operated as and when needed.

You will find a variety of sensors in the modern automobile. These sensors help in ensuring that the vehicle is operating in the most efficient manner. They are built into the car and help in picking up issues as and when they occur. Here are the main sensors present in cars:

1. The Mass Air Flow Sensor (MAF) - This is a computer-controlled sensor, which performs the job of calculating the volume and the density of the air which is taken in by the vehicle engine. Through this, it ensures the right amount of fuel is utilised in order to optimise the operating conditions. A faulty MAF sensor can be a reason for your car stalling or an increase in fuel usage.

2. The Engine Speed Sensor - This is attached to the crankshaft and monitors the spinning speed of the crankshaft. This sensor will prevent the car from halting.

3. Oxygen Sensor - This sensor measures the quantity of the unburden oxygen which is present in the exhaust pipe. It then shows how the fuel is burning (rich or lean). A malfunction of this sensor will cause the car to idle poorly. It also will contribute to jerks and increase the consumption of fuel.

4. Manifold Absolute Pressure Sensor - Abbreviated as MAP, this sensor senses the engine load. It is mounted on the intake manifold and measures the difference between the pressure of the intake manifold and outside it. This pressure is important as it helps the engine to adjust the fuel injection based on it.

5. Spark Knock Sensor - This sensor ensures that the fuel burns smoothly, and isn’t exploding internally. A detonation can cause the head gasket to fail, and other damages too can occur, like; cracking of piston lands, breaking of rings and damages to rod bearing as well.

6. Fuel Temperature Sensor - It helps in ensuring that the vehicles fuel consumption is as efficient as it can be. It helps in injecting the right amount of fuel so that the vehicle runs smoothly and efficiently, wasting no fuel.

7. Voltage Sensor - It manages the idling speed of the vehicle. This sensor ensures that the speed is changed as needed.

Following are the switches you may find in vehicles and their applications:

1. Rocker switches are perfect for dashboard functions, as they can be illuminated to indicate the on/off status. They are also a great option for forward-reverse applications.

2. Toggle switches get activated manually by either a lever or some other form of mechanism. They are versatile and can be used in almost all types of commercial vehicle applications. The basic light switch is a well-known example of the toggle switch.

3. Push-button switches get activated by a push; they are a type of momentary switch. These are commonly used as automotive horns. Other examples include door jamb switches, door lock switches etc. Anti-vandal switches are a popular subtype of the push-button switches.

4. Rotary switches are operated by rotation. These are used when multiple positions are needed and easy access to selection is also required.

5. Disconnect switches cut off the electrical load going from the battery to the rest of the system. They are used for safety and to avoid battery drainage when the vehicle is on idle for a lengthy period. Some of these have the feature of lock-out/tag-outs and detachable keys and handles, etc.

Here are the options available in relays:

1. Change Over Relays are by far the most common type of relay. They have a standard 5 pin connection and can be wired to be normally open, normally closed or change over (both normally open and normally closed). When used as a changeover, the relay will switch current from one circuit to the other and back. It will do this based on the state of the coil as being on or off.

2. Normally, Open Relays have four pins that allow them to be wired in only one way and are normally open.

3. Potted Relays are like other relays, but have one difference. Its bottom is sealed with an epoxy for a waterproof enclosure.

4. Flasher Relays possesses two or three pins. The two-pin flasher is connected to the power supply and the light circuit. The three-pin flasher is additionally connected to the indicator light, which will allow you to know if the flasher is on. All flashers don’t operate like relays even though they’re grouped within the relays. Some behave more like circuit breakers. Thermal (Standard) Flasher, like most flasher relays, are thermally controlled akin to a circuit breaker. With the way the current flows and their process, there’s a constant making and breaking of contacts produced. This leads to a flash pattern of the turn signals, depending on the number of lights which are connected to a thermal controlled flasher it will affect the output performance.

5. Electro-Mechanical Flashers are capable of handling higher loads and provide improved performance as compared to thermal flashers. The number of lights connected to such a flasher doesn’t have much effect on the output.

6. LED Flashers are fully controlled electronics that are completely electronic in nature in terms of control as well as operation. These are controlled by a solid-state Integrated Circuit board also known as I.C. The output of the flasher doesn’t have any connection with the number of lights and it is designed to work on low current draw of LED lighting.

7. Wig-Wag Flashers are also known as alternating flashers, employing a solid-state flash circuit to alternate between two separate lamp circuits.

8. Skirted Relays have an extended skirt present around the bottom which seals around a socket keeping it safe from water and contaminants.

9. Time Delay Relays are adjustable to maintain the current flow through contacts. The current flow duration can be adjusted from 2 seconds to 3 minutes after the power supply is switched off to the coil. A common use for these relays is for powering the vehicle parking lights for a long time after exiting the vehicle in order to see around the vehicle.

10. Dual Open Contact Relays are like the changeover relay as they also have five pins, but they have a dual set of contacts instead of a single one. These are commonly found in European vehicles.

Relays present in automotive are single-pole, single throw (SPST) or single-pole, double throw (SPDT). They also draw little current and have either normally closed or normally open contacts. These operate via a control circuit which has the coil and load circuit, which has a switch of its own. As and when power is applied to the coil, a magnetic field is created. This field will either open or close the switch. Engine coolant sensor or the ECT measures the temperature of the coolant or antifreeze mix. It can hence show how much heat the engine is giving off. This sensor is continuously working and hence makes sure the engine is at the optimum temperature at all times. In order to get an accurate reading of the engine temperature, the ECU will send regulated voltage to the CTS. Since the resistance of the sensor varies based on temperature, the ECU can hence monitor the changes in it. This reading is then used by the ECU to calculate the coolant temperature and adjusts the fuel injection, mix and ignition timing. The ECU also controls the electric cooling fan switch. The information gathered is also used to send an accurate reading of the engine temperature to the gauge on the dashboard.

A bad sensor will project one or multiple symptoms as mentioned below:

• Reading on the dashboard is irregular
• Engine overheats
• Check engine light is on
• Engine sound is rough during idle
• Performance of the engine is limited
• Decreased fuel economy 

Relays may show the following symptoms if not working properly:

• The Engine is running hot
• The cooling fan is not working
• The cooling fans remain on at all times 

Switches will show the following symptoms if there is a problem:

• Problem when switching between modes
• High beam issues
• The lights have stopped working

Do you enjoy repairing your car on your own? Thinking of opening up your own car body shop? It is a great business opportunity if you love cars and possess a good work ethic. But if you want your shop to be successful, then you will require a combination of effort and car mechanic training. And of course, the correct equipment which would upgrade your speed and make your repair work easy. If you will have the right tools, then you can easily meet the demands of today's car body structures. Here are some of the most essential tools which you might need to repair your car switches & sensors & relays.

• Screwdrivers
• Sockets
• Ratchet

If you know which car parts brand suits, the best for your car switches & sensors & relays, then it would save a lot of your decision-making time. What we believe is that picking a particular brand would always be helpful in reducing the clutter, and would make it easier for the customers to find what they are actually looking for. That’s why we have listed out some top brands for car switches & sensors & relays below:-

• Blue Streak (HYGRADE MOTOR) Switches And Sensors And Relays
• Standard/T-Series Switches And Sensors And Relays
• Bussman Switches And Sensors And Relays
• Four Seasons Switches And Sensors And Relays
• Cooling Depot Switches And Sensors And Relays
• Denso Switches And Sensors And Relays

If you are like most of us, then you won’t know much about the related components of car switches & sensors & relays. Fear not! Here is a quick and easy guide to explain the related parts of the car switches & sensors & relays.

Do you want to know the repairing cost of your car switches, sensors & relays? If yes, then keep on reading further! If you are seeing blown Car Switches, sensors & Relays signs from your vehicle, then it means that a repair bill is coming. More than other failures in a car, nothing is like a faulty Car Switches, Sensors & Relays. Now if your car Car Switches, Sensors & Relays goes bad, then it would cause a lot of issues in the functioning of your car and it would turn into an abandoned home. Don’t worry and just think about the happiness when an empty shell would become whole again and much better than it was earlier through quality Car Switches, Sensors & Relays replacement. Keep in mind that the Car Switches, Sensors & Relays replacement cost would depend upon the type of automobile, brand, as well as various other factors. The average cost for a mass airflow sensor replacement may be between $269 and $387. Labour costs can be roughly estimated to start from $38 and go up to $48. TheDo you want to know the repairing cost of your car switches, sensors & relays? If yes, then keep on reading further! If you are seeing blown Car Switches, sensors & Relays signs from your vehicle, then it means that a repair bill is coming. More than other failures in a car, nothing is like a faulty Car Switches, Sensors & Relays. Now if your car Car Switches, Sensors & Relays goes bad, then it would cause a lot of issues in the functioning of your car and it would turn into an abandoned home. Don’t worry and just think about the happiness when an empty shell would become whole again and much better than it was earlier through quality Car Switches, Sensors & Relays replacement. Keep in mind that the Car Switches, sensors & Relays replacement cost would depend upon the type of automobile, brand, as well as various other factors. The average cost for a mass airflow sensor replacement may be between $269 and $387. Labour costs can be roughly estimated to start from $38 and go up to $48. The replacement parts may be priced between $231 and $339 approximately.

• To replace the speed sensor, you may have to pay, on average, between $330 and $380. The labor could range between $80 and $100, while parts will cost you about $265 approximately.
• The cost to replace the oxygen sensor yourself can be between $20-$94 approximately, depending on the brand and type of sensor you buy. The mechanic may charge anywhere between $113 to $478 approximately for parts and labour.
• The average cost for a MAP sensor replacement may be between $149 and $188 approximately. Labour costs are estimated between $45 and $58, whereas parts may be between $104 and $130.Estimate does not include taxes and fees.
• Note about price: The cost of this service or repair can vary by location, your vehicle's make and model, and even your engine type.
• For the knock sensor, you can expect to pay anywhere from $120 to $500 for replacing it. The parts cost will be anywhere from $65 to $200 approximately, while the labour costs will be anywhere from $50 to $350 approximately.
• The average cost for a fuel temperature sensor replacement is between $287 and $345. Labour costs are estimated between $220 and $278 while parts are priced at $67 approximately.

Follow the steps to replace the sensor:

Step 1 - Locate the Sensor

Normally the CTS will be in the engine's front, near either the radiator or thermostat housing. Remove the engine cover to be able to find it easily if it’s present near the latter. 

Step 2 - Remove the connector cable from the Terminal

Unfasten and remove the connector by which the CTS is connected to the ECU. Be careful while doing this as the plastic connector as well as the wiring can be brittle. They may also need full replacement if broken. Now disconnect the connector and place it such that it's out of the way for the rest of the steps to be performed.

Step 3 - Loosen and remove the old sensor

Unscrew and remove the coolant sensors. Use a deep socket and ratchet, to carefully loosen the sensor moving in an anticlockwise direction. Do not apply too much pressure while doing this. If needed, squirt some release spray to free up stuck sensors. Once it is loose, simply unscrew it by your hand and remove it safely from the socket. Most likely some amount of coolant will leak out, so be ready with a new one to replace it or drain out the coolant as needed.

Step 4 - Install the new sensor

Clean the area of any dust and debris using a rag/cloth. This is important so that the new CTS isn’t negatively affected by this dirt. Now set the new sensor in and screw in a clockwise motion with your hand. Make sure the sensor is well-seated in the socket, don’t be in a rush to do the installation. Using a torque wrench, tighten the sensor as per instructions by your vehicle manufacturer.

Step 5 - Reinstate the connector cable

You can now reconnect the cable. Ensure the connector is clean and free from any debris. Plug it into the new sensor and tighten the clips to make sure the connection is good with the terminal. Start the engine and as it’s warming up monitor the temperature gauge present on the dash, and see if the correct temperature is being sustained. This way, you will know if your installation was successful.

Replacement of the relay requires the following three easy steps:

Step 1 - Locate the relays

You can refer to your vehicle's manual to find out the exact location. It is possible that your vehicle may have more than one fuse/relay box.

Step 2 - Replace the faulty relay

Switch off your car and remove the faulty relay out. Keep it aside and insert the new relay in the right position. Be careful and use a minimum amount of force to remove it and install the relay. This will ensure that none of the wiring and connectors get damaged during the process.

Step 3 - Verify the repair

Now turn the key on, and start your vehicle to see if it works properly. Once you’re satisfied, simply replace any covers or panels you may have removed to gain access to the relay.

Replacement of the Switches requires the following easy steps:

Step 1

The first and the usual step is to ensure that the engine is cool. Open the hood and warm the engine enough to notice if the radiator fan is turned on or not.

Step 2

If the fan doesn't turn on, the switch may be faulty. Trace the wire that goes from the fan to the electrical connector and disconnect the fan by pulling the connector part.

Step 3

Identify the cooling fan switch and this can be done by following the wire from the connector. The switch is usually on the tank of the radiator or the engine. Remove the wire from the switch too.

Step 4

Loosen the switch from the radiator or the engine with the help of a wrench and socket.

Step 5

Install the new switch in the place and hand tighten it. You can also use Teflon plumbing tape on the threads to prevent leaks in the future. Use the wrench to tighten the switch back and fill the radiator with the coolant to check for no leakage.