around about 4 weeks ago now I bought a 2007 fiat Punto active for my girlfriend as a surprise for Christmas. When I bought the car all was sound with it apart from the passenger window which was temperamental to opening and closing. I didn’t think of it as much as a deal until the full beam on the car wasent working. I checked the bulbs and they were fine and also checked the fuses in the fuse box but still no resolution to the problem.

4 days after this problem I went outside to unlock the car and there was no response as the battery had gone flat (due to USB port plugged into ciggarette lighter I believe). When I got the battery charged up I tried to start the car but had no response. The dashboard and radio came on but the car made no attempt to start. At this point I realised the imbolisier light had come up on the dashboard (the car with the padlock) and was confused as the car was perfectly fine till then.

I rang a mobile mechanic who told me to get the key checked out which I did and was told it was working fine. So I took it into my own hands and started to look for the fuse that controls the immobiliser, I worked out that it was one of the 7.5amp fuses so I took them out one by one and tried starting the car. When I removed fuse number 48 the car started up straight away! Weird right! Although 10 seconds later the horn sounded constantly and only turned off when I removed the key. I disconnected the horn and started the car again and placed fuse 48 back into the fuse box whilst the car was running.

This just caused the car to not switch off even when the key had been removed completely. I then had a mobile auto electrician come round for a diagnosis who imformed me that the bcu/bcm needed changing and that it was a fiat only job! So I went to fiat who claimed they had to do their own diagnosis (wasted £80 on the other guy). They took the car in and informed me that the fuse box had water ingress and they wanted £730 to repair it. Obviously I wasent going to pay that as I only payed £1100 for the car and there could have been more underlying problems once they were able to diagnose the car.

I took the car away and decided to remove the fuse box myself and clean it up. I cleaned all the water out which was minimal and sprayed everything with contact cleaner. I then hung the fuse box in the airing cupboard for 15hours before putting it all back together again. I refitted the fuse box and the car started first time!! Even with fuse 48 in there, I was well chuffed and started making sure everything worked. I left the car running for an hour and then turned the car off and on again and it started up again, no warning lights nothing! I had literally left the car for 5 minutes and my girlfriend went outside to check the car out for herself,

she went to start it up and nothing happened, I was back to square one and so confused. I removed fuse number 48 and it started first time again. I checked the handbook and checked which components on the car are controlled by fuse 48. So there were 3 options, drivers side window, electric Mirrors and reversing light. I checked all three of these with the fuse out and they all worked fine, even the passenger window works without fault. My question is do I just leave the fuse 48 out if it seems not to affect anything or should I remove the fuse box again and let it dry out for longer? Sorry this is so long but I needed to explain every detail ? thanks, Ollie

Hi Ollie and welcome on board

Very nice and complete description of your issue !! I wish all where like yours ;-)

Weird things may happen with water ingress, moisture AND bad grounding on our GPs, regarding the fuse box I guess you're talking about the one under the bonnet... Anyway if you want to get rid of ANY moisture in it here is the trick you need:

- remove all water you can with towels, rags, etc
- buy yourself a 5kg dry rice pack
- using a plastic storage box, make a 5cm rice layer at bottom
- lay the fuse box on that layer
- cover the whole thing with the rest of the rice
- cover the box
- let the rice 'suck' the moisture for a couple days (the longer the better)
- remove the fuse box, inspect for corrosion, fix if any
- blow with DRY air (pressurized can like used in computers), reinstall

That's what we use when attempting to fix cell phone dropped in the toilet ...

The other common electrical fault is the battery to ground cable that rottens, many posts about that one on the forum !!

BRs, Bernie

If someone here helped You fix -or better, understand- your issue, hit the thanks icon @ bottom right corner, it's free and makes us feel helpy ;-)

Hi Bernie cheers for your reply! And yes I had to be thorough with the description lol. I am referring to the fuse box under the bonnet, it’s the only one the car has strangely. I already removed all the water I could see in there and left it in the airing cupboard which is pretty humid, so I can give your advice a try, if that doesn’t work then I will leave it in the airing cupboard for a week or so, it’s a very strange occurrence

There are more fuses in the Body Computer behind the glovebox (BCM/BCU) Most electrics on the car run through it including the immobiliser. I haven’t experienced the exact problem you have however damp in the body computer could potentially cause your problems. The other thing that springs to mind is that all the functions on fuse 48 are items that have wiring that’s in the doors. If the insulation on the wiring that runs from the body to the doors is fatigued breaks in the insulation can cause all sorts of problems with shorts before the wire actually breaks. If you have something shorting to live you could have power being fead back to the computer potentially causing all sorts of problems. That left unresolved could result in failure of the body computer.
If your happy the fuse box checks out and still getting problems. Then check the wiring from the body to the doors that runs through the rubber sleeves between them. If that’s ok then pull the computer out check all the plugs for corrosion. Body computer is behind the glove box on a Grande Punto.

I had water in a Multipla fuse box (internal). There are many layers of copper inside that and it tracks between them. I cleaned and dried etc. and it did not work. Fitted 2nd hand box. All fine. Then took old one apart and found the tracking and corrosion inside ... it is not obvious. It might be this sort of thing ??
I had all sorts of weird things happening but she has been fine since.

MultipleMultis said:

I had water in a Multipla fuse box (internal). There are many layers of copper inside that and it tracks between them. I cleaned and dried etc. and it did not work. Fitted 2nd hand box. All fine. Then took old one apart and found the tracking and corrosion inside ... it is not obvious. It might be this sort of thing ??
I had all sorts of weird things happening but she has been fine since.

Click to expand...

I’m going to put the fuse box back in the car tommorow and hope that it works fine, if not I will check the internal fuse box for corrosion, it seems impossible considering it’s a component inside the car but I’m determined to sort out this problem rather than paying fiat to do it at extreme prices thanks for your help

You do not need MUCH water.. just enough in the WRONG place.

My experience of damp fuseboxes was extreme.

Alerted by Headlights flashing in a parked fiat.. as if they were indicators

Partially repaired.. at least you have a chance of a replacement board ...or unit.

If it comes to that.

Just to update I have finally sorted the issue! After nearly paying fiat dealership £800 to replace fuse box and harness and no guarantee there would be further problems, I sourced a second hand fuse box from eBay for £30 and the car works perfectly, my girlfriend is now insured and driving it around with no problems at all, 3 months of stress for such an easy fix! Proper chuffed!!

Hi Ollie,

which one of the fuses box did you finally replace ?

Cheers, Bernie