When, Why & How to Bypass ASD Relay? Everything Explained

The automatic shutdown relay (ASD) is crucial in the power supply module. It helps to turn off your car by preventing ignition or fuel pressure. You may need to bypass the relay if the direct line suddenly malfunctions or in case of any emergencies. But how to bypass ASD relay of a car engine?

To bypass the ASD relay, you need to open the relay house first. Then, energize the vehicle coil to have a flexible contact. But before that, take a look at the wiring diagram of the ASD relay. And then locate a path for current flow. You will also need a fuel pump substitute.

Relay is the simplest and most accessible part of your car. It’s a simple on/off type button with great importance. But you should learn the bypassing process of the relay with due diligence. 

What Is the ASD Relay?

The ASD relay is a pretty popular name in the automotive industry. It is basically used as a power button to shut down the car engine.

Whenever you signal to stop the ignition, the logic module sends the message to the ASD. Then, the ASD relay cuts the power from the ignition coil, fuel pump, and injectors. After shutting down the car, the relay driver keeps it that way.

If it doesn’t work correctly, like unable to respond, the relay driver will immediately trigger a code. Even when the car’s logic module is not working, the relay will know whether the circuit is open or not. But when the relay stops functioning, it will mean no engine shut down, and you would need to find a proper solution quickly.

When and Why Required to Bypass ASD Relay?

The main two reasons behind bypassing the ASD relay are engine knocking and struggle with engine starting. It will reduce the engine knocking and help start the car engine when you bypass the ASD relay.

Here are some symptoms to know when you should bypass the relay.

Stalling Of the Engine When It Starts:

When there’s a delay in engine operation after turning it on, it will indicate a faulty relay in your automotive. This mainly occurs when the ASD relay messes with the ignition coils and hampers the flow of the power supply to the injectors.

In fact, you may not be able to unlock the car doors because of the relay failure. The ASD relay will hamper the path to get enough power to the engine, and eventually, the engine will sputter.

The Check Engine Light Will Be Eliminated:

As mentioned, the ASD relay is connected with a logic module, hence the car’s computer system.

Therefore, it may mess with the check engine light and eliminate it. This will be the signal to the driver about the faults of the relay.

However, not every check light signal needs to be related to ASD. That’s why a computer scan verifies the exact problem.

The Engine Fails to Convert Power into Motion:

The crankshaft helps to convert the engine power into motion. But a lousy ASD relay causes the failure, and the engine’s unable to convert the energy. Even the circuits of the engine system may go faulty because of a defective or bad ASD relay.

When the ASD relay shuts down automatically, the circuit won’t function properly, and the engine won’t kick off even after the ignition.

What Causes a Good Relay to Go Bad?

There are many reasons behind a good relay going bad or faulty. The voltage spikes within a range above three nanoseconds can affect the relay of your car.

When the relay goes through hot switching inductive or capacitive loads, it affects the lifetime of the relay and damages it gradually. Even mechanical failures like the degradation of contacts will damage the ASD.

When you connect a low impedance with a high one, it will produce some substantial current source that can damage the ASD relay. However, the lifetime of an ASD relay totally depends on your usage.

How to Bypass ASD Relay?

There are two methods to bypass the ASD relay of your car: the easy method and the substitutional method. Here are the details of both approaches.

The Easy Method For Bypassing Asd Relay:

In this method, all you need is a jumper wire and a few minutes to bypass the less critical relay. But if the situation is worse, you may need a replacement.

Step 1: At first, turn off the engine if it’s running. And then open up the car hood.

Step 2: Find some space where you can place the jumper wire while connecting.

Step 3: Then, locate the positive terminal of the engine battery and connect one end of the wire with it.

Step 4: Take the other end of the wire and connect it with the positive terminal of the ASD relay.

Step 5: Start and run the engine for a few minutes, and your machine is ready to perform.

Step 6: After that, shut down the engine and let it be cool. And then, remove the wire from the joints.

The Substitutional Method For Bypassing Asd Relay:

The substitutional method requires some tools and extra time to bypass the relay and replace the fuel pump. Here’s how:

Step 1: Turn off the engine and locate the relay section.

Step 2: Open the relay and find the spring. The spring should close the contact while the engine is off.

Step 3: To energize the coil, you need to contact the spring so that the current can flow.

Step 4: When the coil is not energized, you will see a pathway at the bottom of the relay to flow the current. Replace the fuel pump with an electric fan.

Step 5: Place a jumper on #87 and #30 pins to ensure the bypass of the ASD.

Advantages and Disadvantages of The Bypass ASD Relay

If you can use the technique properly, there shouldn’t be any trouble after bypassing the ASD. But every process has some pros and cons.


  • You can drive the car with no major issues
  • Keeps the engine functioning
  • Gets you enough time until you find the real problem


  • Can cause damage to the electrical system in future
  • Any wrong move can damage the circuits

Things to Consider While Bypassing ASD Relay

You need to maintain some caution and follow some tips to succeed in bypassing the ASD relay.

It’s best to follow the ASD relay diagram while attaching the jumper wire with the battery and relay. Don’t use the jumper wire if the ASD relay is in a critical situation. Always be careful when connecting the pathway for current and replacing the fuel pump.

Follow the described steps specifically for the bypass. Well, you can also ask some professional automotive consultants to help.


The ASD relay doesn’t provide power to the engine directly, but it surely acts as a switch to pass on the power to ignite and run the machine. It directly affects the crankshaft portion sensor, PCM, ECU, and fuel pump.

So, whenever you feel like there’s a problem with the ASD relay, you must troubleshoot. Therefore, it’s crucial to know how to bypass ASD relay. Hopefully, the techniques will help you to perform on your own. If necessary, draw a diagram first, but don’t take unnecessary risks while bypassing the relay!

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