DIY: Main Relay Repair

james'99

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If you want to check the operation of your main relay to see if it is working properly or not, watch this video first. It was for another forum member as you will hear me referring to a more specific problem but I think this is helpful.

http://www.youtube.com/watch?v=n274dSk2R9M

Obviously to protect myself...

NOT RESPONSIBLE FOR DAMAGE DONE TO YOUR CAR FROM THIS DIY. *SHOULD YOU DECIDE TO DISCONNECT THE BATTERY BEFORE PERFORMING THIS PROCEDURE, YOU WILL NEED RADIO CODE*

So first, lets locate the main relay.



Disconnect it.



You will now have to remove the 10 mm bolt on the main relay bracket and slide the other wire harness off its clip to remove the relay with the brace as previously mentioned by xci.ed6. The harness is connected to the relay in this photo because I took this photo after re-installing the relay. I did disconnect the brake pedal switch to make the bolt easier to see.



The red arrow indicates the connector you will slide off the bracket in order to remove the relay from the car.





Remove relay from housing. I used my knife to pry it open on each side and then slide it out.





Warm up your soldering iron and then reflow each solder joint on the back of the board. Make sure each joint melts fully for the most optimal reflow. I believe there are 26 total.





Put relay back into housing and reinstall in car. Make sure you don't forget to slide the gray harness back into its clip and reconnect the brake light/cruise control switch if you disconnected it to perform this procedure.





Installation is exactly reverse of removal!
Let me know how this works out for you if you decide to go this route!
 
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xci.ed6

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Hey, I showed up!

But, yeah, this is an excellent thread, simple, working process.

A+
 

james'99

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Haha xci! Don't you always?

This thread...

http://6thgenaccord.com/forums/showthread.php?t=48617

And thank you for the support on it! I appreciate it! I have to say, being only 20 years old and doing a lot of work on this particular car and watching your name pop up in these forums all the time has really helped grow my knowledge! Thank you for being such an asset to me and more importantly, this community.
 

james'99

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Time to bump this! Warm weather is coming and main relay issues will soon follow! Nice to do this regardless of whether you have an issue or not just as preventative maintenance if it hasn't been done before on your car and your relay is the original.
 

xci.ed6

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It sucks if these have a problem. I had an 86 Acura Legend with this problem and did that solder thing to make it work. Then I researched it and there was a recall, I think, so I thought they changed what kind of solder they used.
 

james'99

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It sucks if these have a problem. I had an 86 Acura Legend with this problem and did that solder thing to make it work. Then I researched it and there was a recall, I think, so I thought they changed what kind of solder they used.

Yeah, its interesting to think about how this type of thing could fail and why. It doesn't make sense. Why don't ECMs fail, etc. Is it different solder? Are smaller solder joints stronger? I don't really know.
 

Sino

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What sort of symptoms would a bad main relay give you? Knock on wood I've got no electrical gremlins, but it's good to know what to look for.

Sent from my Galaxy Nexus using Tapatalk
 

james'99

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What sort of symptoms would a bad main relay give you? Knock on wood I've got no electrical gremlins, but it's good to know what to look for.

Sent from my Galaxy Nexus using Tapatalk

Basically, your car won't start. It will crank and crank. The main relay controls the fuel pump and primes it when you turn the key to on. No prime, no start. You'll notice at the moment that your check engine light briefly tests when you turn the key to the on position. If your main relay is bad, the car won't start and the check engine light won't test. This can be seen in the video above.
 
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autexil

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I've done this fix in the past and it was surprisingly simple - even for a novice in soldering as I was. Highly recommend this DIY as long as you have steady hands.

Also, during the course of reading & researching, I found a great resource at http://www.tegger.com/hondafaq/mainrelayoperation/badmainrelay.html

Scroll down to the explanation by Michael to get a good understanding of why solder joints go bad. IMHO always best to have an understanding of why the part failed even as you repair it.
 
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