Welcome to Just Commodores, a site specifically designed for all people who share the same passion as yourself.

New Posts Contact us

Just Commodores Forum Community

It takes just a moment to join our fantastic community

Register

VP interior illumination fuse blowing

Filippimini

New Member
Joined
Oct 20, 2012
Messages
117
Reaction score
0
Points
0
Location
Wollongong
Members Ride
VP Calais, 1965 Morris Mini
The fuse for the interior illumination circuit in my 92 VP Calais keeps blowing. It will last a couple of days then die.

I'm guessing there is a short somewhere in the circuit. Any common problems with this circuit?

Also, I checked the rating on the main globe. It is meant to be 12v 10watts. However the one in there is 12v 18watts. Will this extra load cause the problem?

Cheers
Ryan
 

Nut Kracker

Donating Member
Joined
Oct 18, 2012
Messages
4,760
Reaction score
149
Points
63
Age
64
Location
Echuca Vic.
Members Ride
VT SS 304ci (195i)
The exta wattage can make a difference. If there was a short it would blow immeadiately, not in a couple of days.
Sound like a circuit over load. If it is slightly over loaded and as the light only stays on for a short amount of time, it's likely the fuse is wearing down until it finally blows.
What size fuse are you using and do you have any other lights besides the dome lamp?
Not sure about the VP, but on the VT, the boot lamp also runs off the same circuit.
 

DJ_Cosmic_Fire

smarter not harder
Joined
Apr 26, 2011
Messages
502
Reaction score
11
Points
18
Location
South East Queensland
Website
www.house-mixes.com
Members Ride
VP S-Pack Oct '91 - VT SrsII Wagon
Your wiring is unstable, 10A is the fuse rating for the VP interior, as stated above the fuse will blow straight as designed - if not the electrical source will search very fast for somewhere to go & destroy everything in it's path to get there (so think lots of smoke & soon after some sort of fire). Take your DMM & check the positive, earth & courtesy lamps for both the centre lamp & rear reading lights for a start.
 

Filippimini

New Member
Joined
Oct 20, 2012
Messages
117
Reaction score
0
Points
0
Location
Wollongong
Members Ride
VP Calais, 1965 Morris Mini
Thanks guys.

The calais has extra lights compared to the standard vp. It has foot well lights front and rear plus the boot, plus the dome light. Tat is why I'm thinking the extra wattage in that globe is causing the problem. I have removed the globe to test my theory. However, I only had a 5amp fuse left in my spares. I shoved it in thinking that it would blow straight away, but it has lasted. This is making me think it is definately the extra wattage of the dome globe.

Am I right?

Am I just checking that each positive has 12v and that the earth is good?
 

Nut Kracker

Donating Member
Joined
Oct 18, 2012
Messages
4,760
Reaction score
149
Points
63
Age
64
Location
Echuca Vic.
Members Ride
VT SS 304ci (195i)
If you look at your wattage, you have 6 lights, lets say for arguments sake 10 watts each. That's 60 watts.
Now to work out the amperage of all that........Wattage divided by voltage = amperage. So 60 watts/12 volts=5 amps.
Ah you say, why then can't I use a 5 amp fuse. That's because it's right on the limit.
You need to allow for current spikes and over load in the system.
You could get away with a 7.5 amp fuse but a 10 amp would be better (and recommended).
Go too high in the fuse amps and you risk damage, because if some thing goes wrong, the fuse takes longer to blow with the result of smoking wires, component damage and or a fire.
 

Filippimini

New Member
Joined
Oct 20, 2012
Messages
117
Reaction score
0
Points
0
Location
Wollongong
Members Ride
VP Calais, 1965 Morris Mini
If you look at your wattage, you have 6 lights, lets say for arguments sake 10 watts each. That's 60 watts.
Now to work out the amperage of all that........Wattage divided by voltage = amperage. So 60 watts/12 volts=5 amps.
Ah you say, why then can't I use a 5 amp fuse. That's because it's right on the limit.
You need to allow for current spikes and over load in the system.
You could get away with a 7.5 amp fuse but a 10 amp would be better (and recommended).
Go too high in the fuse amps and you risk damage, because if some thing goes wrong, the fuse takes longer to blow with the result of smoking wires, component damage and or a fire.

Yep, I get that. The thing is, as I said earlier, the 5amp fuse is lasting, but I do not have the main globe(18w) in. I will change the main globe back to a 10w as its meant to be and the fuse back to 10amp as its meant to be and see how I go.
 

Nut Kracker

Donating Member
Joined
Oct 18, 2012
Messages
4,760
Reaction score
149
Points
63
Age
64
Location
Echuca Vic.
Members Ride
VT SS 304ci (195i)
Yep, I get that. The thing is, as I said earlier, the 5amp fuse is lasting, but I do not have the main globe(18w) in. I will change the main globe back to a 10w as its meant to be and the fuse back to 10amp as its meant to be and see how I go.

The 5 amp fuse will last, but as I said before, it will degrade with the load until it blows.
Go back to the 10 watt globe and the 10 amp fuse and I think you will find all will be ok.
 

Filippimini

New Member
Joined
Oct 20, 2012
Messages
117
Reaction score
0
Points
0
Location
Wollongong
Members Ride
VP Calais, 1965 Morris Mini
So I still have this problem. I have discovered that if I leave the globe out of the Dome, the fuse won't blow. But it sucks not having a dome light. I've removed the dome fitting and checked for shorts but there is nothing there. What else can I look for?

Ryan
 
Top