faulty Ecu fix ( won't prime fuel pump)
03-01-2005, 01:04 PM
#1
faulty Ecu fix ( won't prime fuel pump)
I had a board laying around here that I was meaning to fix, and this made me want to, so I took 10 minutes of my time and took some pictures for everyone to kinda see (the pics are a little blurry) what I mea, about the caps eating the trace, I fixed it, took it out to the car, and it fires right up. 
Here is the trace under the big cap at C14 ( this is the one that goes to the fuel pump pin
) You can see the cap has burnt through the board and it has broken connection to a resistor right below it.
SO to fix this, take that capacitor out and junk it, get a spare ecu, that is junk and take out another capacitor that is good.. I recommened changing caps with a new one, but I just wanted to get this done to post it on here (for those that like pictures and bold letters). Just order one from digi key if you don't have a spare board to pull it from. Take a jumper and wire it from the burnt up trace side of the capacitor and run it to the resistor.. DONE!
Modified by 93turbo16 at 5:27 PM 3/1/2005
Modified by 93turbo16 at 5:35 PM 3/1/2005
Here is the trace under the big cap at C14 ( this is the one that goes to the fuel pump pin
) You can see the cap has burnt through the board and it has broken connection to a resistor right below it. SO to fix this, take that capacitor out and junk it, get a spare ecu, that is junk and take out another capacitor that is good.. I recommened changing caps with a new one, but I just wanted to get this done to post it on here (for those that like pictures and bold letters). Just order one from digi key if you don't have a spare board to pull it from. Take a jumper and wire it from the burnt up trace side of the capacitor and run it to the resistor.. DONE!
Modified by 93turbo16 at 5:27 PM 3/1/2005
Modified by 93turbo16 at 5:35 PM 3/1/2005
03-01-2005, 01:17 PM
#2
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Re: faulty Ecu fix (93turbo16)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote »</TD></TR><TR><TD CLASS="quote">You can see the cap has burnt through the board and it has broken connection to a resistor right below it.
</TD></TR></TABLE>
No, I can't see. You mean that blurry brown blotch? The picture is pretty bad. If your camera doesn't do well at close range, just take a picture at 4 or 5 feet in a larger size and crop it down.
</TD></TR></TABLE>
No, I can't see. You mean that blurry brown blotch? The picture is pretty bad. If your camera doesn't do well at close range, just take a picture at 4 or 5 feet in a larger size and crop it down.
03-01-2005, 01:20 PM
#3
sorry, I can only work with what I got. I just did it to help out, if you can't tell that the big *** brown spot doesn't look right, then you shouldn't touch the ecu.... LoL
(Sorry for the Pics, once again, I tried it a few different ways, the camera just sucks...)
(Sorry for the Pics, once again, I tried it a few different ways, the camera just sucks...)
03-01-2005, 01:32 PM
#4
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Re: (93turbo16)
Okay, so onto the "how-to". Why exactly are you getting a second ECU just to replace a faulty capacitor? You can buy a new tantalum capacitor on Digikey for $1.00.
03-01-2005, 01:33 PM
#5
As I stated, I have about a billion faulty ecus laying around. So I just took a cap from one of those ecus that was good, the ecu was still bad.. mostly getting them in trades, because someone tried to chip it and hacked it all up..
I said I didn't order a capacitor b/c I wanted to post this.. you can buy a capacitor if you wanted from digikey, I had a spare ecu to pull it from.
I said I didn't order a capacitor b/c I wanted to post this.. you can buy a capacitor if you wanted from digikey, I had a spare ecu to pull it from.
03-01-2005, 01:36 PM
#7
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Re: 93turbo16 (Die-Laughing)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by 93turbo16 »</TD></TR><TR><TD CLASS="quote">
You do have to worry about acid eating the board.... it eats through the traces..</TD></TR></TABLE>
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by 93turbo16 »</TD></TR><TR><TD CLASS="quote">
eat your words.. </TD></TR></TABLE>
ok, I am still correct about what I said and rather then eating my words I will better explain...
what you are trying to show people a pic of but can't see very well is NOT a PCB trace that has been eaten by capacitor acid. you are looking at a burnt trace caused by too much current being drawn through that perticular trace at the time the capacitor decided to fail in which electrically looks like a short. since that is a filter capacitor with one lead on +Vcc and the other lead connected to gnd, when the capacitor shorts it essentially shorts the ECU power supply to ground. when you force that much current through that tiny trace it will blow like a fuse.
having said that, my previous statement "you don't have to worry about acid eating through your PCB" stands true
You do have to worry about acid eating the board.... it eats through the traces..</TD></TR></TABLE>
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by 93turbo16 »</TD></TR><TR><TD CLASS="quote">
eat your words.. </TD></TR></TABLE>
ok, I am still correct about what I said and rather then eating my words I will better explain...
what you are trying to show people a pic of but can't see very well is NOT a PCB trace that has been eaten by capacitor acid. you are looking at a burnt trace caused by too much current being drawn through that perticular trace at the time the capacitor decided to fail in which electrically looks like a short. since that is a filter capacitor with one lead on +Vcc and the other lead connected to gnd, when the capacitor shorts it essentially shorts the ECU power supply to ground. when you force that much current through that tiny trace it will blow like a fuse.
having said that, my previous statement "you don't have to worry about acid eating through your PCB" stands true
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03-01-2005, 01:40 PM
#8
Either way the capacitor IS what eats through the trace, and this is how to fix it.
THe capacitor leaks the electrolyte and that is usually what eats the traces.
http://www.tmo.com/howto/ecu1g/caps.htm
THe capacitor leaks the electrolyte and that is usually what eats the traces.
http://www.tmo.com/howto/ecu1g/caps.htm
03-01-2005, 01:48 PM
#10
Re: (beepy)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by beepy »</TD></TR><TR><TD CLASS="quote">I know how to fix a trace, but I still can't tell what it is you are doing in the second pic. Is that the underside of the board?</TD></TR></TABLE>
If you get your board out, the capacitor is connected to that resitor on the top side of the board, by the trace that got eaten.
So you connect the capacitor at C14 with the resistor at R21, and the easiest way to do it is from underneath.
If you get your board out, the capacitor is connected to that resitor on the top side of the board, by the trace that got eaten.
So you connect the capacitor at C14 with the resistor at R21, and the easiest way to do it is from underneath.
03-01-2005, 02:21 PM
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Re: (93turbo16)
I read and they are wrong. there's no point to continue this convo since you did point out a problem and how to fix it, but caps don't leak battery acid and they do not eat at traces. traces burn out from caps failing and becomming a short, thats it. I have fixed many boards as well and they will all look the same if there has been a cap that causes a current surge through a small trace.
I was just correcting what is the cause of these issues so people understand what is going on. either way the problem and solution info is good
<--- eletrical engineer in case that holds any merit
PS: just to be aware, any electrical component can fail as a short and cause a trace to burn out, it just so happens that caps are the most unreliable component and are usually the component to fail.
I was just correcting what is the cause of these issues so people understand what is going on. either way the problem and solution info is good
<--- eletrical engineer in case that holds any merit
PS: just to be aware, any electrical component can fail as a short and cause a trace to burn out, it just so happens that caps are the most unreliable component and are usually the component to fail.
03-01-2005, 05:17 PM
#14
Re: (turbosi03)
yes that does hold merit because that is my major as well, every article I have searched has a "leaking" capacitor causing the short or the damage. How does the capactitor short out on the inside? There are two equal charged plates ( or any material for that mater) that have a potential difference across them, and they hold charge, and they don't make it. I just don't understand where everyone in the world gets a leaky capacitor statement, if it just isn't true, even published articles.
Just looking to gain knowledge at this point, don't care now if I am right or wrong. I would like to understand this concept a little better.
It is the short that eats the traces. Aftermath of the short is the leaky capacitor.
Modified by 93turbo16 at 4:13 PM 3/10/2005
Just looking to gain knowledge at this point, don't care now if I am right or wrong. I would like to understand this concept a little better.
It is the short that eats the traces. Aftermath of the short is the leaky capacitor.
Modified by 93turbo16 at 4:13 PM 3/10/2005
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