This guide will teach you how to diagnose, locate, remove, and repair the Main Relay in a 1999 Honda Accord LX 4 cyl.

--->There has been a recall on Honda Accords from 1999-2002 due to the ignition switch wearing prematurely this may cause the same engine behavior as a faulty main relay. Call your nearest Honda dealership and inquire about a free ignition switch replacement.<---

  • The first and easiest thing to do to diagnose your main relay is to simply insert your key into the ignition and turn it to the RUN position. All sorts of warning lights will come on briefly and then turn off, the one you will be looking for is the check engine light. Normally it will come on briefly and then shut off.

  • Your main relay supplies power to your engine computer, spark plugs, injectors, fuel pump, and your engine immobilizer.

  • When you turn the key to the RUN position and the check engine light doesn't come on, (to put it simply) your computer isn't receiving any power due to a faulty ignition switch.

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  • Another test you can do is to once again insert your key into the ignition and turn it to the RUN position and listen carefully for a series of clicks coming form behind the dashboard.

  • Normally, right after you turn the key you will hear a click and then after a few seconds you will hear another click. However if the main relay is faulty you will not hear any clicks. Those clicks are the main relay switches turning on and off.

  • Another way you can tell if your main relay is faulty is by listening to your fuel pump. Normally when yo turn your key you will hear a faint buzzing noise coming form the back of your car. However if your main relay is faulty you will not hear the fuel pump turn on.

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  • Lastly we will test the main relay directly. This involves removing the relay from its housing.

  • The main relay is located

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To reassemble your device, follow these instructions in reverse order.

6 other people completed this guide.

Nick Miller

Member since: 08/19/2015

250 Reputation

1 Guide authored


I have replace my main relay my ecm the coil but my cr still not running it sound as if it had no gas but the injectors are working and the fuel pump. Before my car stop working. It would be running just find till I turn it off. Then I have to wait till it would cool down to start again can anyone help?

Miguel - Reply

Is there a gas smell in your oil if so give it a complete oil change.

Chyna Redd - Reply

Um, how about finishing this?

Wade Rackley - Reply

Cm for camshaft codes or cranksensor code orno1 cylindercodes replace distributor

Pedro LaCourt - Reply

While Miguel's is an old post waiting for an engine to cool are signs of electrical breakdown, which is the coil works while cool and quits when it warms up and maybe the crankshaft sensor falls in the same category. I don't know where this was headed but there are Yuo Tube videos of repairing the main relay, pull open it and look at the solder joints checking for cracks.

Thomas Loecken - Reply

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