ENG: MAIN RELAY REMOVAL AND REPAIR (pics)

[rootzcb7]

so question, do you resolder each connection or just the round pointed ones in the center and the short sides

[ikayto]

so question, do you resolder each connection or just the round pointed ones in the center and the short sides

i soldered every connection



Dont know if I did it right, I just soldered over the older solder points. I think the more correct way is remove the older solder, but I'm not that pro yet.

[9threeEX]

Thanks for the DIY write up with pics, before I found this forum I always thought it was hot weather vapor lock. I'd just roll down the windows and open the hood and wait a while. A real PITA and kinda embarassing.....

[verderacer]

Just followed the DIY and no problems.

I did take a few pics along the way and just edited one up and all you have to do is label it and put it up if you like. It clearly shows the hidden bolt what normally should be seen in pic 3 and 4 of the DIY.

Let me know if you want it !

[revzCB]

GREAT info bro

I have had the no starts on hot days symptoms for a long time now eversince my mom still owned my CB (my CB was a hand me down when mom's got a new car)

already knew that it was my main relay causing the problems from other past honda experiences, just been lazy to do it

but yah atleast now i know what to look for,since i havent gone under there and looked at it before. Great post bro

[illestatus]

great write up, its hard to explain without pictures, i wish i had known before, i bought my relay a while back and it cost me like 70!! oh well i guess you live and learn

[4CYLPOWER92]

Thanks for everyone's compliments
I have not had anymore main relay issues since I did this. Hope everyone else has had good luck as well.

[tgdrums1990]

I finally decided it was time to fix my annoying main relay. After reading countless threads on this forum and others, I've noticed that pictures and detailed instructions are impossible to find. Vague drawings in repair manuals are all I've seen for the most part.

Here we go!

You need a socket wrench with an extention or 2, a size 10mm socket, and some patients. You might even want to do some yoga before attempting this. The location of the main relay in our cars is the main reason this job is hard.



Put your upper body including your head, down on the floor board where your feet normally go. Now look up left of the stearing columb, above and left of the fuse box. You won't be able to see the main relay yet. The cruise control box is in the way.
So there are 2 10mm bolts holding the CC box in place. Remove those and slide the box out of the way.
Here is the CC Box dropped down by the foot rest.


Now you should be able to see the main relay.


Now don't bother unconnecting the connector yet. It is a tight space to work in, and the connector is tight. There is one 10mm bolt holding the main relay case to the car body. Take that bolt off. Now, you might be able to remove the relay at this point, but maybe not. There is a black plastic box painfully close to the main relay, and the metal relay bracket is undernieth that plastic box bracket. Take off the other 10mm bolt to that bracket in order to loosen it up. Now with a few wiggles, the main relay box comes right out. Now you can unconnect the conector, with the help of a screwdriver for a little prying.


Here is the culprit:





The problem that causes us all pain. These are the 2 locations that looked obviously cracked to me. There could be others that are hard to see visibly, so I went ahead and resoldered every single connection.


Now I'm not an experienced person at soldering, in fact, I've only attempted it once or twice before. It's not that hard. I got a 30amp solderer from Radio Shack, and the thinest wire they had.


I've read somewhere before, that after soldering, you should drill some holes in the main relay holder box. Not sure of the purpose of this, maybe it keeps the relay cooler. Can't hurt, so I did it. I used some sharp surgery scissors to put 4 holes through the casing, since I have no drill.

Installation is the reverse of removal. It wasn't that difficult, really.

Then pray you didn't damage the relay, and start the car
Mine started right up. Now only time will tell how the resoldered joints hold up. I'm keeping my fingers crossed.

very nice write up,

The holes are to allow the box to breath. As that thing marrinates under the dash in those hot summers it will cause those bad solder connections you seen lol... As to if it really works are not. I think it's more of peace of mind, In thoery it makes scence.

The only other thing I suggest is to get some contact cleaner and clean the contacts of the relays them selves....

[i-07]

and a tip from a friend is to put vent holes in the cover on it so it will not over heat lol

[xaaronx]

did this today, so far so good.... i was so worried i completely butchered my relay because i haven't soldered in so long and it kind of looked like hell lol.

[tru2037]

WOW this probably has helped so many people! I have crawled up under the dash and never knew what the hell I was looking for. I am going to do this right now!

[jkrolikowski]

Main Relay's relation to erratic idle

I could be wrong and I haven't seen anyone mention this on this forum or any others, but I'm at the end of my wit here with my erratic idle and am going to test/replace the main relay next (PGM-FI Main Relay is what it's called I guess, but I've also seen it labeled as just "main relay" - anyway, it's the same one pictured in this thread). Over the past 5 months, I have done everything mentioned in this forum to solve my erratic idle aside from check/replace coolant thermostat and check/clean/replace MAP sensor. I'm throwing a code for neither thou.. And I've done EVERYTHING else. In my mind-numbing research on this erratic idle dilemma I came across a note in italics at the end of the section on testing our IACV in the Haynes manual for our cars that says to check the main relay for damage or poor connections (sorry, I should have the manual with me to write it word for word, but I know most of you have this manual). In addition, you can see in the schematic in the back of the Haynes manual that the PGM-FI/Main Relay is connected to the IACV (Note that in the schematic the IACV is labeled EACV - generic label?). See for yourselves. Based on the schematic, it seems to me that this relay controls the fuel pump, regulates the injectors (? - not sure about this one) and acts as an intermediary between the ECU and IACV (EACV).

Thoughts? I'm gonna test this tomorrow and let you know.

[SilverShadow]

The only "main relay" I have ever heard mentioned is the one shown at first post. I know that relay in like said, in car, under the dash. You may be reading about the idle control valve. You may have clogged EGR ports. Anyway keep going through the possibilities and if you get lucky the engine code will falsh and help you narrow it down. GL

main relay that I know of


Fast Idle control valve (I think that's what it's called)

[jkrolikowski]

The only "main relay" I have ever heard mentioned is the one shown at first post. I know that relay in like said, in car, under the dash. You may be reading about the idle control valve. You may have clogged EGR ports. Anyway keep going through the possibilities and if you get lucky the engine code will falsh and help you narrow it down. GL

main relay that I know of


That's the same relay I'm talking about.

Fast Idle control valve (I think that's what it's called)

That pic is of both the FITV and IACV, both of which I have cleaned, inspected and replaced.

[SilverShadow]

Good..then you can eliminate that as source,unless you didn't replace relay with new and have same one in there. Just know that the points break. But if you're confident it's fine...move on to something else.
Go after the small easy stuff and then the larger. If you did a tune up then all those suggestions are gone. Sounds funny, but yes a simple tune up will help a severely sputtering engine (That was me 100%) My wagon went maybe 20mph up hill like a newbie on a manual. You have idle problems, almost the same problem. Did the big tune up myself and the car went ZOOM! Could work in your case too.