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Old 11-13-05, 04:24 PM   #1 (permalink)
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Post PGMFI Main Relay Removal

Because the most of us knows, that a Bad Main Relay is the most common problem. So I thought to write this DIY -Mike

What It Does
Our Main Relay is also known as "PGM-FI Main Relay". It controlles all power going to the ECU and fuel pump. This one operates the fuel pump, and supplies power to the fuel injectors. Without this thing in proper working order, your car is going nowhere.

Symtoms Of Bad Main Relay (Outside)
Getting symptoms of a bad main relay means usually, that on very hot days, say 90 F +, sometimes our cars are difficult to start. Sometimes it seems to be very random. You notice that during the engine turns over with no problem, but will not start. It sounds like it's not firing. After 5-10 min's, it will eventually fire and the engines starts. The other getting reason could be, if the starter cranks but don't start, then in most cases, you may have a bad main relay! I suspect the main relay is temperature sensitive. Sometimes I'm afraid it eventually will leave me stranded, but it's not happened till today.
Another common problem also caused by the main relay is, that our car starts fine, but stalls as soon as you release the key. In this situation, it may take many attempts at starting before the car will continue to run with the key released. Don't laugh, it really happened. Really !

Symtoms Of Bad Main Relay (Inside)
Bad Dry Joins
The first cause could be the well known "Hairline Cracks". A bad main relay is a common fault like "Possible Hairline Cracks" or "Bad Dry Joints". The last item is sometimes possible through any vibrations and changes in temperature cracking the solder around a joint. This can cause intermittent failures, which are especially likely to happen when the car has been parked in the sun on hot days.

Hot Main Relay
Another cause could be a Hot Main Relay. That means, that this relay should not get hot even if the pump is drawing too much current - until the excess current starts to kill the contacts. There are 3 possible reasons for a hot relay:
- Cold Solder Point
- Bad Crimp Joint
- Bad Relay Contacts

Over time these bad joint gets worse due to the heat (heat cool cycles), the resistance goes immediately up, the joint gets hotter, the voltage at the pump goes rapidly down. So then it needs more current to do the same work so the joint gets hotter, it gets worse.

How To Check
Sometimes it helps to see what's going on in this relay. Our Main Relay will click 3 times during the starting process. If problems arise, one of those clicks (usually the third) is missing. If you can hear all 3 clicks, the Relay is fine. You don't need to replace it.

Turn ignition to ON: Click 1
CEL light goes off: Click 2
Turn the key to start: Click 3

Click 1
When you turn on the ignition switch to "ON" => Position II (don't turn to start) you should hear a click and a hum sound at the fuel filter. That means that the fuel pump gets energized. If you don't hear it, it's probably the main relay.

Location
This one is located behind the lower dash panel on the left side. It's a small box labeled "Mitsuba Relay Main Assy RZ-0105" in white letters on it. It's easy to get access for it. It's held with a 10 mm screw and a small self-locking hook.

Material
All you need is a simple screwdriver and a 10 mm nut and rachet.

How To Remove The Dash Panel
Please see Dash Panel Lower Removement

How To Remove The Main Relay
After you have taken off the panel, you will see now our Main Relay.



Now take a 10 mm nut and rachet and turn it counterclockwise to remove.





Now unclip both connectors and you got it

Inside The Main Relay
A relay is an electromagnetic switch. Anytime you want to switch a device which draws more current than is provided by an output of a switch or component you'll need to use a relay.

When power or ground is applied to a coil, the relay clicks on or off. The result is, that a power wire to a function is either closed (connected) or opened (disconnected). When the line is connected, the function is turned on and works. When the line is disconnected, the function is turned off and will not work. A relay can be used on alarm systems, things like to disable a starter, to flash the parking lights, and so many more of them.

Now let's take a look inside our relay...
Actually our Main Relay contains 2 separate relays. One of them is energized whenever Ignition (IGN) is powered ON. It supplies batterie (BAT) voltage to the ECU, power to all 6 injectors and power to the second relay.
The second relay is energized for exactly 2 sec's, when ignition is switched ON, and when the engine is running. It supplies power to the fuel pump.






How To Repair
Like above described, a typically "Bad Dry Joint" looks like, when it have small cracks around the pin and PCB track. But you can see that when you look very closely. These have a characteristic look...


Try to inspect your circuit board of your main relay. That's the cheapest way. But you need somebody who's a genie or have the well know know how about electronics. This a tricky work, but for somebody who does have the needed knowledge it's really easy to fix. To fix it, you will need to...

1. Remove the solder from all connections
2. Re-soldering your connections
3. Inspect the joints for any imperfections
4. Spray on conformal coating, and wait till it's dry
5. Re-assemble in reversed sequence

To get more infos I recommend you to read the PGMFI Main Relay Repair tutorial. Excellent taken pics will guide you through the entire knowledge to get your Main Relay repaired. I strongly recommend you to read all pages! It's worth a shot. A must to see this, really
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Old 11-13-05, 06:14 PM   #2 (permalink)
 
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AWESOME POST!!!!!!!!!!!!!!!!!!!!!!

It should be MANDATORY for every new member to read this post and take a quiz on it before they are allowed to post.
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Old 11-13-05, 07:02 PM   #3 (permalink)
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Great DIY Mike!! Very detailed and informative. I know where I am going to look if I ever have this problem.

Thanks for spending so much time to help us all out!
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Old 11-13-05, 07:12 PM   #4 (permalink)
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Mike are you reposting everything from when all of your threads got deleted? Looking very good sofar man keep it up everybody loves you for this!
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Old 11-14-05, 05:40 AM   #5 (permalink)
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Quote:
Originally Posted by Cole Austin
Mike are you reposting everything from when all of your threads got deleted? Looking very good sofar man keep it up everybody loves you for this!
Hi Cole
long time no see. Sigh, yes I do. Around 3000 posts got deleted and no one knows who did it. As far I know my old post counter was by 7340 but this is not the problem. The problem was the whole effort for me to write it in your language. Naah, it's ok. I'll do my best to re-write all. German would be sooo much easier for me, but it's a US Forum. Please have a lil bit patience, because it needs a bit time. And you know, I'm not the fastest just because of the damn language barrier, right ? Oh, and greetings to Jordan. I still miss her -Mike

To OhGeez & Jason Thank you very much for your great compliments
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Old 01-07-06, 08:24 PM   #6 (permalink)
 
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PGM-FI Main Relay in RL model

Mike -

Very nice job on this post. I ran into this problem a couple of days ago on my '96 Acura RL. It just died. It restarted once for about a minute and then died again. Of course, I had never visited this site before the problem so I had no idea what was going on. I was also 900 miles away from home! Fortunately we had two cars & I had the shop manual and tools and VOM with me and got it fixed.

When I went to the dealer to buy the part I got a good tip which I would like to pass on here. On the RL the relay is very difficult to get at and is up high under the dash to the right of the steering column. The service manager told me that rather than trying to remove the entire unit that the 'technicians' leave the relay case in place and remove the insides and then replace them with the guts of the new unit. This would save some time.

There are a total of 4 tabs about 1/2" in from the ends on each of the long sides of the case. You can carefully insert a small screwdriver (or two) and pry out the circuit board.

When I get home I'll try to repair my old PGM-FI so that I can carry a spare with me.

Bob
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Old 01-08-06, 03:55 AM   #7 (permalink)
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go Mike! your DIYs are great!
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Old 04-02-06, 05:37 PM   #8 (permalink)
 
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This morning I decide to take off the pannel out on the driver side to take ou the main relay. I have anacura 93. I took 3 crews out one of them is hide inside you have to take off the pannel out. So, the rest is so easy.
Tool 8mm and 10mm. I did go to autozone just borrow and return the tool .
My car sometime not start when it was hot. It just happend is one for amonth. So, if it often happend I will buy the main relay 80 - 85 buck I can change myseft. I did open the main relay to see inside. You have to use magnifier to see. This website i learn a lot after mechanic riff off 2400 for fix my transmission. My car only 126.000 mile do not trust any mechanic. You have to research before you decide fix or not. So, right now I just go to this website to learn how to fix simple thing for saving my money.
hope you do the same
HP
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Old 04-03-06, 03:51 PM   #9 (permalink)
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location usa huh??
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Old 08-25-06, 03:53 PM   #10 (permalink)
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I'd like to thank all you jerks who pissed miked off so he took down his pics! Augh!
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Old 09-09-06, 07:46 PM   #11 (permalink)
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Quote:
Originally Posted by duck
I'd like to thank all you jerks who pissed miked off so he took down his pics! Augh!
James,
I completely reorganized my sub dirs a long time ago because of my forum and its different dir's. It should work now . Just wondering why I only can see the links and no pics in my old posts. Stupid thing is, why I can't edit my old posts. IMO your Admin should change the

Settings Usergroup ID 2 => Post / Thread Permissions => Can Edit Own Posts

settings inside vB! So I'm not able to re-edit my old posts and to change it -Mike
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Old 09-09-06, 08:34 PM   #12 (permalink)
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Originally Posted by MikeD
James,
I completely reorganized my sub dirs a long time ago because of my forum and its different dir's. It should work now . Just wondering why I only can see the links and no pics in my old posts. Stupid thing is, why I can't edit my old posts. IMO your Admin should change the

Settings Usergroup ID 2 => Post / Thread Permissions => Can Edit Own Posts

settings inside vB! So I'm not able to re-edit my old posts and to change it -Mike
Hey Mike,

I dunno why this happens, but we cant edit any of our own threads that are really old. I can't even edit my posts in the Newbie FAQ anymore .

Ill bring it up with the admin and see what we can do about it
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Old 09-10-06, 06:10 AM   #13 (permalink)
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Quote:
Originally Posted by Daddymac117
Hey Mike,
I dunno why this happens, but we cant edit any of our own threads that are really old. I can't even edit my posts in the Newbie FAQ anymore .
Hi Nick ,
for 'Registered Users' the Standard Settings of Can Edit Own Posts permission is always on No. Don't ask me why. Stupid thing.

Quote:
Originally Posted by Daddymac117
Ill bring it up with the admin and see what we can do about it
Yep that would be fine. I'm sure most members would appreciate it very well. I have made 4 snaps. I'm sure your Admin does know what I mean Sorry but I forgot his 1st name.


Just a side note:
Are you able to edit my post? If so then please cut the snapshots and move it to your Mod Forum. I know that these things don't belong to this forum. Esp not in the DIY forum.
Thank you, Nick See you sometime -Mike

Last edited by B+O; 09-10-06 at 09:02 PM.
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Old 09-10-06, 12:51 PM   #14 (permalink)
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Cool, i posted the question in the mod forum for you, Mike

And I'm only the moderator for the The Lounge section (so far ) lol. I don't have access to edit anything outside of The Lounge...

This'll probably get edited once the problem is fixed
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Old 09-10-06, 01:54 PM   #15 (permalink)
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Hey mike, let me know what you need to have moved/edited. i can get it for you
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