Blown instrument fuses

This may sound like a silly question.........but are you putting the correct 'amp' fuse in? If you are, then there must be a short somewhere in that circuit.

 

I wonder if your alarm system might be tapped into the wiring loom for the instruments? There isn't much chance (in my opinion) that there is anything wrong with your instruments or the sending units that would cause a fuse to blow. It's more likely a direct ground in the wiring.

Does it make any difference if the Climate Control system is completely shut off when you start the car? I notice in the wiring diagram that one of the items fed by power from fuse #6 is a relay for part of the A/C system. There is also a feed to the exhaust temp ECU for the 5/8 bank. Are your exhaust ECU's unplugged?

You might be able to narrow the problem down a bit by taking off the central panel for the oil temp/fuel gauges and unplugging them, and by removing the main instrument panel (two screws) and unplugging the harness connectors one at a time to see if that prevents the fuse from blowing.

I'm betting that the short has something to do with "non-Ferrari" wiring, or possibly a component screw that has penetrated a wiring bundle.

 

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I would suspect a short. You must be getting close to getting that car sorted out soon, unless you bought an 'Ernie'.

BT

 

LOL!!!!!!!

 

I can't think of anything that would cause fuse #6 to blow after having a rundown battery.

Just for an illustration, I pulled off the center console instrument panel (one minute job). Your car probably has components for your alarm system back in this area. You can see how the long screw in the picture has almost hit the wire bundle. That screw is about an inch too long for its purpose. If it was chaffing against the bundle, it would eventually wear through and potentially cause a short. When alarm installers do their thing (or stereo installers, or radar detector installers,....) they often leave things in a position that will cause trouble up the road. I'm just suggesting that you pull off this panel and have a look around. There aren't too many areas on the car where you could get a direct ground through this circuit, and in my opinion, this is where I would look first.
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Undo the two screws that hold on the shifter gate, slide the black horizontal panel slightly back (be careful with the fragile piece on the front of the ashtray housing), then wiggle the main vertical piece with the two gauges out. It isn't screwed or clipped in place, it's just sitting there. You have to pull it slightly downwards to clear the radio housing. Then just look around in there. Check for any signs of a bare wire that might be touching something, or a screw that may have penetrated a wire bundle, anything unusual. You might not find anything, but it's an easy first step. And if you install a new fuse and turn on the ignition, you MIGHT see or hear something arc when the fuse blows. You're using a 10amp fuse, right?

When you put it back together, make sure you install the shift gate with the little "jog" in the reverse position.

 

Thats why I mentioned that you use the correct fuses when replacing them. If it keeps blowing the 10amp fuse, then going to a 15amp fuse is not the way to go about it. There must be a problem there. If in fact it is supposed to be a 10amp fuse there or is there supposed to be a 15amp fuse there? Putting a 'bigger' fuse in, can melt the wiring before the fuse will blow. If you know what I mean? I have seen it many many times before. Unknowing people replace a 5amp fuse with a 10amp fuse and down the track, could be 5mins or 2 years later, something would happen and then they melt some wires, because the fuse was supposed to blow at 5amps, not 10amps.

 

Can you possibly post a picture of this "giant connector"? Doesn't sound like a Ferrari part, probably part of the alarm system.

It's hard to believe that something would blow a 10amp fuse and NOT blow a 15amp fuse, but there you go. Something isn't right. The book says that the proper fuse for that circuit is 10amps, and if it's blowing a 10amp fuse, then the circuit is overloaded, which means that heat is going to be produced.

If the alarm system isn't being used, I would find out where it is attached to a power source (probably through an inline fuse, not a fuse in the panel) and I would disconnect it, then see what happens. I guess I'm fixated that the problem has something to do with aftermarket wiring or components, which is not necessarily the case.

 

Thats exactly right brother. I did the same thing to my old Ford in 1999. Cost me $600 to replace part of the wiring harness under the dash that melted. I got an Auto-elec to do it back then. I have seen so many customers do it, mainly because they dont have a 10amp fuse or whatever to replace, so they replace it with a bigger fuse- 15amp-25amp or whatever. Crazy.

 

They usually 'hide' the car alarm modules under the dash somewhere. Usually closest to battery power/fuse panels. But not neccessarily either. Could be anywhere under the dash. The siren is also usually hidden, to deter theives from trying to break in, then spending time trying to find the alarm to kill it. Maybe they have used that circuit to power the alarm, thats why it is overloaded and blowing the 10amp fuse.

 

No

Who replaced the battery might I ask ?

 

I've got two large black connectors like that under my A/C panel that go to my mouse motor seat belt ECUs.

 

I would be surprised if the alarm is anywhere other than under the radio. There just isn't enough room under the dash. It could be under the trunk lining and wired into the front fuse panel somehow. Do you know how to remove the trunk lining? Can you follow the wires from the "giant connector" behind the center console and see where they go? Don't confuse the alarm with the seat belt modules (black boxes), which are mounted on the floor under the radio.

The alarm system should have a main module, possibly a box about 4" square and 1" thick, and maybe a motion sensor about 1" square by 2" tall. They usually have crudely installed wiring with lots of cable ties around them.

I don't think there is any possiblility that your battery is causing a problem.

 

Don't think so but were you sure that you fitted all the wires to the correct terminal post? Or was there just one single thick wire lead to each side of the negative and positive posts of your battery?

 

Having the same problem on my 355, fuse no. 24 (a/c system and instrum.). Doesn't happen until i put the foot down and rev. past 6 or 7K. Does anyone know what else is on this circuit? I read that on the 348, fuse 6 (which does the a/c and instrum.) also feeds the cat ecu. is this the same on the 355?

Any help would be greatly appreciated, if anyone has the wiring diagram, can they please check it for me.

Thanks guys.

 

Common guys, someone must know the answer to this?