yes. i had the same problem. there is a capacitor for the ignition system. it is located to the left of the oil cap. its a little black box with 2 wire coming out of the top of it, one wire grounds near the passenger strut tower, and the other go towards the motor. check the wires on that. if ones loose its shorting, blowing the fuse. look for signs of elecrical arcs around it, if theres arcs, thats your bug.

according to the parts guy at ford its a VERY common focus issue, and they had quite a few in stock. cost 20 bucksish. simple fix, unbolt the ground, unbolt the capacitor, and replace. bada bing, bada boom.

 

according to the parts guy at ford its a VERY common focus issue, and they had quite a few in stock. cost 20 bucksish. simple fix, unbolt the ground, unbolt the capacitor, and replace. bada bing, bada boom.

This is the first time I've heard of it on this board though. I'll keep it in mind.

 

Sounds like a suppression capacitor. Just out of curiosity- how does that manage to blow the ECU fuse?
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Sounds like a suppression capacitor. Just out of curiosity- how does that manage to blow the ECU fuse?
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My son has a 2006 Ford Focus ZX4 2.3L and it blows this Fuse sometimes. I took that Suppression Capacitor off and it still blows the fuse the same.

 

Probably by the sudden arcing of it and the fact it's gotta lead to the ECM. It is strange but would make a ton more sense I'm sure, if we had a wiring diagram we could look at.

 

How do we know it has a lead to the ECM? Why would a suppression capacitor have volts on it, enough to arc?
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Is it that little black thing, passenger side towards the rear of the car on the engine? (sounds like it) I ask because a local member showed it to me and asked what it was and if it was ok to have one wire pulled out of it like it is.

Does that thing give off any other symptoms aside from the OP's problem?

Edit: btw niggly I don't know.... What I said had no evidence and is probably incorrect other than that someone said that's the exact same problem and replacing it fixed it, so it apparently has a connection...

 

I really don't think that is his problem.
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A search shows that some other people with blown Engine management fuses have had bad alternators.

 

I don't either because the one guy's is partially broken like I said, and he doesn't have issues with it... But did once in awhile which is why I asked if it had other symptoms.

So far if Willis says that's the same problem, I'd suggest trying that before tearing apart anything else. It's not TOO expensive....

 

A suppression capacitor is fitted to reduce RF radiation. There would be no link to the power supply to the ECU. Any circuit protection would be internal to the ECU. The problem is elsewhere, but without access to wiring diagrams I can't help any more atm.
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Ok it is the same thing I'm thinking of....

I gotta agree with you though... Need a diagram.

 

Thanks for that whynotthinkwhynot.
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The part that is being discussed is a radio noise suppressor. The part itself is not causing the fuse to blow. The problem is that when the hot lead touches "ground" the the fuse blows. You can run without this, but will have a noisy radio. Both leads were broken off on mine. It cost me $14.50 and all is well. Obviously a poor design, but oh well, all is good.

 

I took mine off and it still blows the fuse. It is something else sometimes to.

 

The item being discussed is a noise suppressor for the radio. The unit itself does not cause the problem, but when the "hot" lead, which is what happened to me touches "ground" that's when the fuse blows. You can run without it, but will probably have a lot of ignition noise in the radio. $14.50 will take care of it. Obviously a poor design, but that's life.

 

Has anyone come to the cause of this problem?
I have the same issue and burned the Green with blue stripe wire in the engine bay.
at first the fuse would blow once a month but now right when the key is turned it pops.
I believe the green/blue wire is a ground wire that runs all through the car as i was tracing it and looking to see if there was a short to power on it some were.
car has been stuck for a week. Any help would be great.

 

Where were it burned at and feeding what ???

 

The radio interference capacitor will blow the PCM fuse if the hot side shorts to ground. I think it's a 20 amp. No one should be surprised that there's a capacitor in the power supply circuit. Capacitors are commonly used in AC to DC power supplies to smooth out the DC output in the rectifier portion of the circuit. The positive side of a capacitor is connected to the positive output of the transformer secondary, and the negative side goes to ground. Usually there's an inductor (or "choke") in there as well. One thing to watch out for in addition to shorted wires is the fact that capacitors can develop internal shorts. In either case, a short will blow the fuse protecting the transformer secondary, and you'll lose power to the whole works.

To test if the RF capacitor is the source of your trouble, simply remove it. I would not leave it that way for long, simply because I have not seen the schematics and you might not want pulsating DC going through the sensitive circuits of your car. If the fuse doesn't blow, then you've isolated your problem. Buy the part and replace.

Toby

 

Blowing main fuse

So on a 2002 with the Ztec engine this does not appear to be the same. Any ideas?

 

Seen an RF capacitor by the Coil on the Zetec, haven't heard of a similar problem from that.

Post a new thread detailing YOUR issue for better answers, this old thread was on a problem for a different engine type.

Welcome to FF!

 

I don't see a a little black box on either of my focus' 2000 and 2003 both with the Zetec 2.0L DOHC. Im having this same issue engine management fuse #9. I checked all the grounds and wires that were exposed taped one that were iffy. And same result. Blown fuse.

Im taking it to the dealership today....

 

Same issue, i had an electrician replace the terminal and connect it all, was working fine until i drove it tonight. I'm assuming it has something to do with the lights on my car because like I said it was running fine until I had to use the headlights tonight. My problem....
I have a 2000 Ford Focus Zetec. The battery was stolen from my car, in the process the thieves cut my negative battery terminal leaving the wires just cut... Would anyone know how these four wires connect, besides the obvious one which is the ground one connected to the chasis/body, there are also a black wire with a red stripe, a black wire with a yellow stripe and a black wire with a light blue stripe... Please help.

 

Same issue, i had an electrician replace the terminal and connect it all, was working until i drove it tonight. I'm assuming it has something to do with the lights on my car because like I said it was running fine until use the headlights tonight. My problem....
I have a 2000 Ford Focus Zetec. The battery was stolen from my car, in the process the thieves cut my negative battery terminal leaving the wires just cut... Would anyone know how these four wires connect, besides the obvious one which is the ground one connected to the chasis/body, there are also a black wire with a red stripe, a black wire with a yellow stripe and a black wire with a light blue stripe... Please help.

Ill take a picture for you later today of the terminals hooked up.
found out why I couldnt find it I was looking for melted wires and or melted plastic cover and didnt find it because the previous owner hid the wires in newer plastic covers and new electrical tape. (Dealer traced short with computer) after splicing the melted ball of wires it runs like a champ. ( melted onto the EGR so I put heat shields on them with hose clamps)

 

Alright so now that my car turned on I started looking around more carefully and noticed some loose wires that i moved last night when i got stranded. Those wires had been burned and looks like they had got stuck on the manifold, being that I see peices of the wires still stuck there. Thanks for the help, and now because of that little incident i found this page and forums, which I find awesome!

Just to let you guys knows i ended up putting everything back exactly how the electrician had left it in the first place, the thicker of the ground wires (black) to the body and the black/yellow, black/light blue, black/orange to the negative terminal.

 

Its a bad design to have the wires running around the EGR system so I used heat-shield wrap to keep the starters and stuff cool and wrapped the EGR pipes just incase the wiring harness gets close so it doesnt melt!

 

In my case, the problem WAS the radio suppression capacitor.
2006 Ford Focus 2.0L
Here are my observations:
1) The radio suppression capacitor, near the passenger shock tower and as described above, has a hot lead that goes from its connector to the "black cube", which is the capacitor itself. This lead is not in a protective loom. The capacitor on my car was dangling, not fastened, it looked like it originally was fastened to a plastic sleeve or mount which had deteriorated, causing the capacitor to now be loose and dangle.
2)The lead passed under a sheet metal mounting bracket, which had a sharp edge. The wire insulation was cut at this point (I'm sure due to general vibration), so the conductor was shorting out against the metal bracket (which was grounded, of course).
3) When the key turned to "run" position, the short circuit described above caused fuse F9, in the engine compartment fuse block, to blow immediately. Upping this fuse (attempt at temporary repair) from 20 amps to even 40 amps did not prevent the fuse blowing. So that capacitor lead really shorts out!
4) I also discovered that a 2nd fuse was blown, a 15-amp in the engine compartment fuse block, I forgot the fuse number, I'm not sure this was part of the same source issue but I bet it was. I replaced this fuse also.
5) Finally, it STILL wouldn't start, and I then discovered the clutch "lockout" switch was bad. Again, unknown if this was part of the same "shorting" issue, or just a coincidence, but did make me go "hmmm".
6) In the end, I replaced the offending noise suppressor capacitor (easy, 5 minutes, $22 seemed to be available at dealer only), the two blown fuses, and the clutch lockout switch.
7) note that the replacement capacitor has a mounting bracket that has a hole in it, for mounting on the bolt on the metal bracket on the car. The oriigiinal capacitor did NOT have the hole, I think it was held on with a crappy plastic jiggy, which then broke and caused this ordeal. So looks to me like Ford revised the part to fix this issue. (As simple as adding a mounting hole is, it's still a revision that tells me "they screwed up" with the original part.)
8) I electrical taped the bejesus out of the new hot wire, since it is loom-less and didn't want to go through this again.

Happy trails.

 

You can take it off period. Don't need it. Took my off and fuse still blows.