How to identify a bad main relay on a Honda (PGM-FI)

1999 Honda Accord with an intermittent no start problem this is a 2.3 liter engine and history of the vehicle is it's had a recent distributor replaced not sure if that's related or not let's go look in the scan tool now see if we have any trouble codes alright got to forgive the glare on the screen here I'm working in the field I'm going to my codes my key is on and you see we have no codes present let's go back go to pending codes we have no codes there to some other stuff you want to pay attention to for nose starts would be anti-theft systems and the thing is with the anti-theft if we haven't missed you there we'd have a flashing key on the dash which we don't and then also we be losing injection pulse another one we can look at that's a nice guide is our rpm so crank it see we have an RPM signal some other things I've shown in the past is let's take a look at this check engine light see what it does turn the key off there's my light top-left corner I'll show it again key off key on there's a check engine light you saw that initial key green key flashing right there with the key off nothing wrong with that as long as it doesn't stay flashing after your cranking so crank it over see we know we have no security issues and again on the scan till we had rpm okay doing a real quick spark test hold on hold on Pete little trigger-happy on me there I was talking to the camera not you all right we're doing a real quick spark test on this Honda I just pulled one of the plug wires off got my test light going to a ground on the strut and we're just gonna see if we have spark here go ahead and crank it okay good all right we got spark all right next quick test I'm gonna go after the injector and see if we have pulse and what I'm going to do is I'm gonna take my test light connect it to battery positive and I'm gonna go on one of the two wires here and I'm not poking my test light into this connector something that was pointed out to me in some other videos where it looks like I'm doing stuff like this I'm not I'm just laying this test light on the top of that terminal right there all right crank it for me okay I'm gonna move my test light over over to the other wire again I'm just resting it there guys I'm not I'm not spreading this female terminal watch our test light guide crank it tough to pick that up in this sunlight let me get my camera closer good crank it okay we have Injection pulse there's other ways to do it too we can leave it plugged in and we can back probe it and I can put a scope on it things like that I mean we're just doing some quick tests here find out what we're missing we do however want to check this injector for power so we'll make sure that we do that I do have injection pulse but let's make sure we have power to the injector I'm just plugged in I'm gonna do a back probe qiyuan Pete good crank it good that's the feed now if I go to the control I'm gonna partially energize this injector which isn't really good good crank it I don't know if the camera picks up that pulse crank it some more there's a slight flicker in that again two different methods showing you injection pulse is there so next thing let's go back and see if we got power to our fuel pump now we could do a fuel pressure test on the rail next but being that there is no straighter valve and that is a little more difficult to do I'm just going to see if we have power on the pump ok I'm back at the pump I'm gonna do a quick power tech just have a test light connect to the ground and I'm gonna go to this pump power feed wire right here and yes I put a small hole in this wire I will fix that when I'm finished this is an interior wire I'm not worried about corrosion anyway but for you guys that hate when I do this I understand but I really don't have an option for where this is now I could take this cover off I take that back I can take the cover off and t-pin it so sorry about that guys okay good crank that for me okay good all right so you see we lost power to our fuel pump so again just some other tests that you can do gives you a guide not really relevant to this car we're missing power on our fuel pump just want you guys to keep that in mind check your rpm that lets you know that cam and crank signals are good and at least gives you a guide to that anyway we can't say with 100% certainty that all of the inputs when the ignition are good but we're not worried about it we have spark we have injection pulse we are missing power to the pump I know what you guys are thinking and you're right it's the main relay and that's where we're going next and so what I've done so far is I've pulled it down I'm not going to take it all the way out yet I have it disconnected from the housing I still have the electrical part plugged in because I wanted to show you guys the arcing you can actually see on this middle terminal right here and I'll get you a close-up shot of that too you see it's it's definitely got the issue a melted solder joint or crack solder joint this one actually looks like it's melted and cracked let's see if I can get some arcing for you I need an extra hand Pete can you crank it for me buddy I'm gonna wiggle this connection here see when we make this car start there it is right there it's running I'll leave it running I want to see if I can get show the arcing in this fed crank it and I had some nice had some nice arcing with it before all right let off I'll see if I can get that shot it was really cool looking okay hold on nice I could show that I'm not try it just makes for pretty cool video that's all I mean it isn't really necessary it definitely needs the needs the fix just like to see the Archangel actually you know what we could do is instead of cranking it just turn the key off and back on and we'll get the fuel pump prime taking place there it was see if I can make to do that again that there it is again okay turn the key back on all right start it back up all right we're gonna pull this really out hopefully you guys saw the arcing it really doesn't matter I'm gonna show you this solder joint how to fix it start it back up again I'm gonna run in the back and get you a get you a reading off of that off of that pump wire okay here's our same wire here's our same wire where we were before you see I got power and that is black and yellow wire at the pump pretty standard Honda color I didn't even grab a diagram I knew it just from working on other Honda's and yes guys I did put a small hole in the wire and I promise you I will fix it okay so don't give me too much crap okay one last order this main relay car is running right now I'm gonna move the relay you'll what you'll hear the car set off just gonna a little bit of pressure on the middle of it so there it was main relay the funny thing with this one you hear it as I'm wiggling it - it's going nuts usually when these relays fail at least in my experience the car never shuts down it only will not restart sometimes but in this case the car was actually shutting off - as well as being an intermittent upstart alright I've got the main relay out just sitting on my tailgate here and you can see clearly this middle terminal it's cracked and burnt so we saw - that one there's another one - and it's on this one right here kind of tough to show you with the lighting I'll try to zoom in on it yeah you can see the crack on that one but right there there's a ton of hairline crack that goes around that that solder joint that's what we look for so I'm gonna inspect the rest of these very closely and then I'll show you the soldering on them I'm pretty sure it's just these two right here so it'd be it would be it would be this one here and then this one here and really if you look at that that's affecting two different circuits so it was more than just the fuel pump I'm sure we were potentially losing power to maybe even the engine computer at certain times it wouldn't have been whenever we caught it though because if we were losing power to our engine computer we'd be losing injection pulse - and we had pulse but but at other times when I was wiggling this I noticed the check engine light coming on and off and I'm pretty sure we were interrupting power to the computer at certain times - the one I caught with you guys though was mainly the fuel pump I believe it would be this relay they said it's really two relays in one in one housing is all it is you got your to conventional relays in a box one of the relays powers the pump and the other one does injectors and I believe the computer and the some other solenoids under the hood I believe idle air control valve - so again crocs are joints I'm going to fix all right the two main ones I see on this style is this pin right here for sure you can see it this one definitely cracked and it looks like this one started I may just hit them all I don't really have to I just won't really wanted to point out where you want to look on the on these ones I showed one of the older designs one of my other videos the reason why this is actually melted here is with this crack over time it's cracked all the way around on this one what we do is we generate resistance there and with resistance in an unwanted location it actually makes heat and that's what melts it so the cracking is just from expansion contraction over and over and over over thousands and thousands of miles of driving and on off key cycles you know any circuit board has this situation it's not really anything unique to Honda just so happens that it's common on this one because this is their design so got the soldering gun very hot that's key using a butane soldering gun again I'm in the field I'm kind of in a parking lot here gonna heat the pins and the solder joint itself and sometimes you can do this without even adding any solder at all it's kind of hard to do here what we want to do is we want to see that melt across the terminals and it doesn't take much and that looks pretty ugly I want to get a little bit more on the board itself just want to make sure that I have a good set on this board it's one this one I just want to reset this one not that slaughter you put your finger on the white part of this back here hold that down - thank you that's the second one when we hit this one again I don't I don't like killing that on the pad itself it just looks like crab to me I want to make sure that we're really getting off on this pad he's too one thing to get them on the pins but we needed to we need to melt it onto the housing of the relay box itself and it just looks crappy to me I'm gonna hit this one too I'll wait for that solder to change color on me that was a good one I don't like this one either I'm gonna hit it anyway I don't want to burn your finger here Pete I was a good one to redo that first one that really looks bad I look at that close-up looks horrible this one was just so badly melted I try to hit it from a different angle I just haven't seen one this bad I like that a little bit better that may be the ugliest one I've done go figure but whatever we're gonna inspect these other ones real close again I don't think I need to hit them and then we'll put this back in the car see what it looks like okay final inspection of this I actually missed a little spot right here we got a little hole so I'm gonna hit that one one more time that's better one soldered pgm-fi main relay let's put it back in the car here you got it back in the car let's give this a shot fires right up I noticed before that on occasion we get a little hook up in the car - and that hiccup is gone and that was just the relay making and breaking contact and before whenever I pushed on this stressed it wiggled it made the car shut off you see we're not doing that anymore so that is a fix I'm gonna show you one last shot and that's where this relay is to see if I cannot for some of you guys want to know where it's at and how to get it out I think the key with this very difficult to unbolt some of these so what we always do infield is we just take the guts out of it there's just two little plastic clips that hold it one here and one here all you do is take a pocket screwdriver and pry out this way and this way and pop the whole thing out instead of unbolting the housing no reason to do that and I'm just gonna install this back into its place and it has a slot see if I get the right direction here that's important looks to me I think it went that way they're like slots in the housing that made me not new it was right in the first place [Music] it goes that way only goes one way guys and push it back in one repaired pgm-fi main relay you

Channel: ScannerDanner

Views: 1,055,325

Keywords: main relay testing, Auto Tech, Engine Performance Diagnostics, Trade School Pittsburgh, auto repair, fuel pump relay test, PGM-FI Main Relay testing, honda main relay repair, cracked solder joint, Tech, Rosedale Tech, training, scannerdanner ebook, injector pulse test, DIY auto repair, Honda Accord, how to check for spark, scannerdanner book, Honda no start problem, Rti, Rosedale Technical Institute, car repair, Rosedale

Id: 6CMZ4g8n0FQ

Length: 18min 19sec (1099 seconds)

Published: Wed Jun 05 2013