Technical Newbie help required - 2021 Fiat Ducato motorhome

[Jenkii]

Good afternoon, I'm hoping for a little help and advice.

We are currently away in our motorhome in 30 degrees (based on a 2021 Fiat Ducato) and we have an issue where fuse 36 under the dash (10amp) has blown. We have tried replacing it and it blows immediately when you try to push in the new fuse.

This fuses the climate control (very much needed right now), radio, tpms, alarm, tachograph and battery disconnecting control unit.

Has anyone had a similar experience?

All battery connections look good so I'm at a bit of a loss at where to start and how to diagnose.

Thanks all.

 

[Grayducato]

Good afternoon, I'm hoping for a little help and advice.

We are currently away in our motorhome in 30 degrees (based on a 2021 Fiat Ducato) and we have an issue where fuse 36 under the dash (10amp) has blown. We have tried replacing it and it blows immediately when you try to push in the new fuse.

This fuses the climate control (very much needed right now), radio, tpms, alarm, tachograph and battery disconnecting control unit.

Has anyone had a similar experience?

All battery connections look good so I'm at a bit of a loss at where to start and how to diagnose.

Thanks all.

You'll have to disconnect or switch off all the after-market stuff, go back to basics, what the vehicle was delivered new with. You might just be overloading the circuit, but DON'T be tempted to put in a higher rating fuse. Of course it's possibly a faulty accessory, you will have to re-connect one at a time until the fuse blows again. That unit will be the problem.

 

[Jenkii]

You'll have to disconnect or switch off all the after-market stuff, go back to basics, what the vehicle was delivered new with. You might just be overloading the circuit, but DON'T be tempted to put in a higher rating fuse. Of course it's possibly a faulty accessory, you will have to re-connect one at a time until the fuse blows again. That unit will be the problem.

Thanks for the advice. The only aftermarket device that's been added is an alarm. I disconnected this today and the fuse still blew.

Could it be a faulty relay for the AC that causes it?

 

[Communicator]

Thanks for the advice. The only aftermarket device that's been added is an alarm. I disconnected this today and the fuse still blew.

Could it be a faulty relay for the AC that causes it?

Without a diagram diagnosis cannot be more than observation, and guesswork.
From your description of the circuits involved it seems that F36 on your vehicle is an ignition on supply for devices that are not powered with the key in the starting position.

I am generally sceptical when relays are suspected as the source of a fault. The thought that reinforces this is that there are at least two relays vital to engine function, specifically the main injection relay, and the fuel pump relay. I have not seen any reported cases of these relays failing in service. However a drowning man will clutch at a straw, and the blower/fan is one of the larger electrical loads in the vehicle. If you postulate an internal mechanical failure of the relay causing a short circuit between the coil and power connections, there ia a remote possibility of the fan being supplied via fuse that supplies the relay coil.

Have you switched off as many of the affected items as possible, before replacing the fuse?

 

[growlybear]

Good afternoon, I'm hoping for a little help and advice.

We are currently away in our motorhome in 30 degrees (based on a 2021 Fiat Ducato) and we have an issue where fuse 36 under the dash (10amp) has blown. We have tried replacing it and it blows immediately when you try to push in the new fuse.

This fuses the climate control (very much needed right now), radio, tpms, alarm, tachograph and battery disconnecting control unit.

Has anyone had a similar experience?

All battery connections look good so I'm at a bit of a loss at where to start and how to diagnose.

Thanks all.

Probably a stupid question to ask based on your location, but has there been a bad storm recently,? I've read that the scuttle drains block easily and water floods into the second fuse/relay box under the bonnet. Worth taking relays out to check for water?

 

[Jenkii]

Probably a stupid question to ask based on your location, but has there been a bad storm recently,? I've read that the scuttle drains block easily and water floods into the second fuse/relay box under the bonnet. Worth taking relays out to check for water?

We have had a fair amount of rain and I have seen water in the air intake. The fuse box under the bonnet is in such an awkward position to take anything out

 

[growlybear]

We have had a fair amount of rain and I have seen water in the air intake. The fuse box under the bonnet is in such an awkward position to take anything out

I've got an A Class so don't have this issue. But that's where I'd start.
I had old VW 1990 LT Florida and condensation from the windscreen would mess up the relays in the fuse box.