Every vehicle needs an appropriate amount of air-to-fuel mixture ratio, which is controlled by the main relay and ECU. Due to many reasons like faulty switches or loose connections, the main relay can fail to operate.
So, can a car run without a main relay? How to bypass it? No, it can’t if the fuel injector is electrically controlled; otherwise, it can. However, you can bypass the main relay by disconnecting the cables, attaching a jump wire, and reconnecting the cables on both terminals.
In this article, we will discuss the importance and the signs of faulty main relays. You will also learn about the bypassing procedures, advantages, and side effects. Thus, if you are also a car owner and frequently face faulty relay issues, go through the article.
Can A Car Run Without A Main Relay?
Generally, a car cannot start without the main relay if its ignition system is electrically controlled. In this case, the vehicle won’t get any electrical signal in the fuel injector. As a result, it will fail to deliver fuel to the engine, and the car will make a cranking noise instead of starting.
The function of the main relay of a vehicle is to control the electricity flow to the ignition system. Besides, it sends the electrical signal to the ECU to provide adequate fuel to the engine through the fuel injector. Thus, it’s a mandatory element among all the vehicle’s parts to operate a car correctly.
However, those cars which don’t have an electronic fuel injector don’t require the main relay for starting but will run slowly. That is because every vehicle requires an accurate air-to-fuel mixture to operate appropriately.
So, without the main relay, the car will run lean. This may cause wear in the engine, reduced engine performance, and engine failure.
What Are The Signs Of A Malfunctioning Main Relay?
Before performing the bypassing process, you must know when to do this. Generally, when the main relay is failing, you may encounter several symptoms like:
Flashing Check Engine Light
When the main relay malfunctions, the ignition system will also malfunction. This will activate the check engine light to illuminate.
Difficulty In Starting
Faulty relays won’t be able to serve adequate power to the fuel system. As a result, the engine won’t get sufficient fuel required to start the engine. Thus, you will face hardship while starting your vehicle.
Malfunction in Starting
In this case, you will face some malfunctioning in the starting system. Sometimes, you will succeed in starting the engine, and sometimes won’t. Besides, the soldering joints will be misaligned when the interior is warmed up. Thus, the car will fail to start.
Engines Die Suddenly
This happens when you drive your car longer with a faulty main relay. You will be successful in starting the vehicle. But it will die suddenly in the middle of the road due to the defective relay.
The power supplies will also cut off when the relay is not working correctly. Hence, you will notice a cranking noise coming from your engine.
How To Bypass The Main Relay?
You can minimize those issues of the defective main relay by bypassing the main relay when you can’t replace the faulty one. The bypassing procedures are straightforward, requiring
- A screwdriver
- A ratchet
- A jumper wire
- A wire cutter
Here are those steps:
Step 1. Locating And Accessing The Relay
At first, you must locate the main relay in your vehicle as the model’s location changes. Generally, you will find this under the hood computer module. This is located near the power distribution module(PDM) or the battery.
Step 2. Disconnecting The Relay
- Pull apart the relay
- Grab all the wire and spin it counterclockwise. After that, the cables will be loosened
- Now, you need to unscrew the attaching screws with the help of a screwdriver
- After this, you can disconnect the relay from the car’s body
Step 3. Cutting The Ends Of the Cable
You need to peel off the insulation from both ends of the cables by cutting them. Use a wire cutter to remove the 1 to 1.5-inch insulation from both ends of the cable.
Step 4. Connecting With A Jumper Wire
Connect a jumper wire for installing it at both terminals of the relay. Make sure the connections aren’t loose, and you can enter both ends of the cord at both terminals of the main relay.
Step 5. Priming The Engine
This stage refers to starting the engine for a few minutes before turning it off. You have to run the engine for almost 15 minutes, then let it cool down after turning it off.
Step 6. Disconnecting Screws
Now, pull out the screws with a ratchet’s help and ensure all the terminals are in good condition. You can use any electronic tape to keep each cord aligned.
Step 7. Adjustment
This step is the reverse process of steps 3 to 5. After that, the bypassing operation will be done, and you can check it by driving the vehicle.
What Are The Advantages Of Bypassing The Main Relay?
There are numerous advantages of bypassing the main relay. Those advantages are:
Solution To Failure In Starting
Sometimes, the car may decline to start due to a damaged starter motor, effective battery, and cracked ignition switch. If you still can’t solve this issue by trying typical techniques, bypassing the main relay is a solution.
Alternative To Ignition Switch
When a vehicle doesn’t have an ignition switch or the switch is cracked and damaged, your car will face starting issues. You can start your car quickly without interacting with the ignition switch by bypassing the relay.
If for any reason, you can’t change the faulty ignition switch to solve the issue, this bypassing is a familiar solution for you.
In some cases, starting a car after a long period may slow the starting process. This happens because the main relay takes time to activate again.
You can easily avoid this issue by bypassing the relay, ensuring adequate energy delivery for starting the car. And also, you don’t have to wait for the activation of the main relay.
Serves Higher Voltage
If you bypass the main relay, the lower amp current will no longer control the higher amp current. As a result, the electrical motors will have a higher voltage. Thus, those electrical motors will show better effectiveness and efficiency at higher voltages.
Besides, the engine has a well-designed fuse that is capable of protecting the engine from excessive voltage.
Ensure Better Performance
Bypassing the relay is one kind of method of elimination of resistance. Hence, the engine will get 100% power through bypassing without interruption. Accordingly, the engine, as well as your vehicle, will show a better performance than before.
What Are The Side Effects Of Bypassing The Main Relay?
In several cases, a bypassed main relay will be helpful for your car and your convenience. But it also poses a lot of side effects. Those are:
- One of the main relay functions is to control the higher ampere current with a lower Amp current. Thus, bypassing the relay will hamper the control, and a higher current level will flow through the circuit. This may blow the fuse of the engine frequently
- Bypassing the relay may reduce the longevity and durability of your car’s engine
- While upgrading your vehicle, bypassing the main relay won’t serve any advantage. You may need to rewire the system
In this FAQ section, we will answer people’s most common questions about a car’s main relay.
Q: How Long Does A Main Relay Last?
Typically, the main relay may last almost 50,000 cycles. This means, in ordinary cases, it can last for your car’s lifetime. Yet, due to some unforeseen and unexpected reasons, it may get damaged and will hamper the car’s performance.
Q: What Is The Cost Of Replacing A Main Relay?
To replace the main relay, you may need to spend around $65-$75. Generally, a new relay will cost you almost $35-$40, and the rest are labor costs. The price of the main relay and the labor cost may vary according to your location and vehicle model.
Q: Is It Good To Bypass The Main Relay?
Generally, no. But if you bypass it for a temporary period, like in an emergency, while testing, or while replacing one, that’s alright. Otherwise, bypassing it for daily use may cause severe damage to the engine.
The main relay is an essential vehicle element that ensures better performance. But sometimes, this relay can get damaged, which will cause many issues in your car. By noticing those issues, you can diagnose the faulty relay.
In this article, we already discussed can a car run without a main relay? How to bypass it? A vehicle generally can’t run or run poorly without this relay, and in an emergency, you can bypass it by the procedures mentioned above. It will relieve those issues temporarily.