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What is a main relay?
The main relay is a device that opens and shuts the fuel system, and in most cars it also opens and shuts the ignition system. A common main relay problem is that the car doesn’t start if the interior of the vehicle gets hot.
What causes a main relay to go bad?
When operated at full load, a relay is said to have failed when its contacts fail to operate (often because they weld together) or when contact material erosion results in an unacceptable high path resistance. When asked to hot switch a load, a relay may only be good for 100,000 operations.
How long do main relays last?
Relays have a limited lifetime, but they are reliable in benign environments. 50,000-100,000 operations are usually at full rated load. Up to many millions of operations with a negligible load will experience an increase in life at lighter loads.
What is difference between fuse and relay?
Fuses & Relays — What Are They? If too much current flows through the circuit, the fuse will blow — interrupting the circuit and halting the flow of electricity, protecting the components further down the circuit. Relays are remote switches that open or close an electrical circuit.
What should I do if I have a bad main relay?
You should still rule out other more likely problems like a dead battery or bad starter before jumping straight to a bad main relay. If you’ve verified that your battery has enough power, you can turn the key to different ignition spots and listen for a click from the fuse box.
What happens when the electronic control relay fails?
As the electronic control relay powers the computer, when it fails it can cause all sorts of issues with the vehicle. Usually a bad or failing electronic control relay will produce a few symptoms that can alert the driver of a potential issue that should be serviced.
Where is the main relay in a car?
The main relay is usually located underneath the hood in the relay box. The high heat that this relay is exposed to can create a lot of damage over time. When the main relay begins to malfunction, you will have to find a way to address the issues in a hurry. Failure to act quickly in a situation like this can lead to a lot of instability.
Can a car start if the relay has failed?
If the relay has any sort of issue it may compromise power to the computer, which will not allow the vehicle to start. For many vehicles the engine’s starting circuit is on a separate circuit and relay than the computer’s, so the engine will still crank even if the computer relay has failed.