Technical Electrical problems

[Soapy1960]

I have a 2000 Fiat ducato motorhome. Recently I noticed that the engine does not always turn off when the key is turned off. Also noticed the headlamps come on when the ignition is switched off, obviously draining the battery. Not sure if it is connected or not. I tried to check wiring but there's all sorts of relays and wiring coming from the battery which was to complicated for me. Any ideas cheers

 

[Communicator]

I have a 2000 Fiat ducato motorhome. Recently I noticed that the engine does not always turn off when the key is turned off. Also noticed the headlamps come on when the ignition is switched off, obviously draining the battery. Not sure if it is connected or not. I tried to check wiring but there's all sorts of relays and wiring coming from the battery which was to complicated for me. Any ideas cheers

Hi Soapy1960,

Welcome to the forum. I have to assume that the headlamps are already selected when when they come on without turning the key.

The common factor would seem to be the ignition switch, which may have developed a fault. Alternatively there may be a wiring fault due to cables chafing and wearing through the insulation.

If as is most likely the vehicle has a diesel engine, the engine would fail to stop if the stop solenoid on the injection pump is sticking open, or is receiving a supply when it should not (ignition switch again).

As you already seem to be overwhelmed by basic MH electrics, perhaps you need the services of an autoelectrician.

For explanation, I would expect to find two additional relays near the starter battery, along with two or three additional fuses. The relays would be for the fridge when running on 12V, and the split charge relay. Two fuses of the would be 15A or 20A rating for these functions.

 

[Anthony489]

Hi

Just to add to the above, with a motorhome it's normal to have a second (habitation) battery. Arrangements are made for this to be charged from the engine alternator when the engine is running, but it should NOT be possible for current to flow the other way, i.e. the habitation battery is prevented from powering the vehicle electrics. However, if there is a fault with the motorhome habitation battery charging and isolation circuit, its possible that this is what is happening. Temporarily isolating the habitation battery by removing one of its terminal clamps should tell you if this is the cause of your odd effects.

 

[Soapy1960]

Hi Soapy1960,

Welcome to the forum. I have to assume that the headlamps are already selected when when they come on without turning the key.

The common factor would seem to be the ignition switch, which may have developed a fault. Alternatively there may be a wiring fault due to cables chafing and wearing through the insulation.

If as is most likely the vehicle has a diesel engine, the engine would fail to stop if the stop solenoid on the injection pump is sticking open, or is receiving a supply when it should not (ignition switch again).

As you already seem to be overwhelmed by basic MH electrics, perhaps you need the services of an autoelectrician.

For explanation, I would expect to find two additional relays near the starter battery, along with two or three additional fuses. The relays would be for the fridge when running on 12V, and the split charge relay. Two fuses of the would be 15A or 20A rating for these functions.

Thanks for your advise. The headlamp switch is in the off position. There are 2 yellow relays next to the battery that are linked together I'm assuming these must be the relays you mentioned. They are very badly corroded so I'm going to clean them and refit them.
I will try and check the ignition switch ASAP. Fortunately the van is not required at the moment but would love to have it up and running for the spring. Once again thanks for the help