Reversing Light

[Grizzly]

I'm wiring this up now but have a question: The power needs to be provided by a ignition switch controlled Live.

I have one in the VG loom but it looks to be a fairly lightweight wire. Will it be OK to use this with a 5 Amp fuse or is a relay required?

[steve in stockport]

should be ok as it is, you only need a relay for heavy draw items.

usually use a 21 watt bulb in rev lights but if you're worried you can use a 5 watt bulb - won't light much up but will tell people you're reversing

 

Steve

[RedTrev]

Hi Grizzly,

Mine has a VG harness and the thinnest wire I see is 0.5mm (csa) thin-wall spec. This has a continuous rating at 20'C of 11A. It should be fine with a 5 amp fuse. An important factor with selecting a fuse, however, is whether it blows in the event of a short-circuit. A typical automotive blade fuse (ATO fuse or Mini-fuse) will blow in less than 0.5 seconds if the short-circuit current is 3.5x the fuse rating. With 0.5mm wire over a relatively short length (no wires on the VG harness are relatively long) you should be safe. I haven't completed my build yet but intend to do a full fuse-blow test on all fuses to ensure they blow in sufficient time during short-circuit conditions. This way you know your wiring isn't going to burn out!!

 

Trev

[Grizzly]

Thanks Guys - That's another job off the list

[RedTrev]

job's a goodun ... or is it?

......are you brave enough to short the two wires together at the bulb end to see if the fuse blows?

 

Short the wires together, select reverse and switch on the ignition.

 

Good result, the fuse blows.

Bad result, the wiring burns out!

 

Remember this short-circuit could happen at any time you are driving the car... you'd like to be sure the fuse would blow.... wouldn't you?

 

In this case I would expect no problems, but it's worth bearing this in mind with every circuit on the car.

 

Food for thought...

 

Trev

[Guest Dan_Beeston]

Trev,

 

Just to drop you in it for the sake of the board! (as I know you're the expert in this kind off stuff )

When you get to the stage of doing your fuse blow tests can you post the results to the board?

 

There are lots of VG looms out there & it would be good to know any areas that are a bit dubious in design/construction!

 

Cheers,

 

Dan

[RedTrev]

Yes, I will post the results no problem.

When you get to the stage of doing your fuse blow tests

(don't hold your breath )

 

I have already made some mods to the harness w.r.t. circuit design.

Off the top of my head, the main ones regarding fusing were, briefly:

 

1) additional fuses (in-cab) to split the loads. There are only 4 originally on the VG and one, for sure, had quite a few loads hanging off it.

2) increase the number of earth points. Some circuits have earth wires running from the back all the way to the front of the car. I've added an earth point in the centre console/facia area, for example, and this has reduced the length of several earth wires.

3) added fuses underbonnet to protect the wiring coming from the battery e.g. to the ignition switch. (Yes, the big beefy ones that have more smoke in 'em).

 

If anyone wants more detail, let me know, and I'll have a look when I get home.

 

Trev

[Guest jacobeon]

Yes, I will post the results no problem.

(don't hold your breath )

 

I have already made some mods to the harness w.r.t. circuit design.

Off the top of my head, the main ones regarding fusing were, briefly:

 

1) additional fuses (in-cab) to split the loads. There are only 4 originally on the VG and one, for sure, had quite a few loads hanging off it.

2) increase the number of earth points. Some circuits have earth wires running from the back all the way to the front of the car. I've added an earth point in the centre console/facia area, for example, and this has reduced the length of several earth wires.

3) added fuses underbonnet to protect the wiring coming from the battery e.g. to the ignition switch. (Yes, the big beefy ones that have more smoke in 'em).

 

If anyone wants more detail, let me know, and I'll have a look when I get home.

 

Trev

Hello Trev,

I'm just trying to fathom my vg loom at the moment and would be grateful for more details on all 3 of your mod's.

Would be very grateful for a few pointers.

Regards Alan.

[RedTrev]

Hi Alan,

You are just up the road at Nuneaton.

Get the kettle on!

I'll send you a PM shortly.

Trev