NS Dev
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| posted on 16/5/05 at 03:02 PM |
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First power up of loom
Just read a thread which is in the for sale section for some reason, and it prompted me to write this.
When first powering up a scratch built wiring loom (as I have done a few times now) a trick I use (and probably many others too!) is to use a 12v 15
amp battery charger instead of a battery, with all the fuses disconnected.
Turn on the charger and watch the ammeter, then insert the fuses one at a time and check each circuit one at a time.
The charger will struggle to power horns, radiator fan and starter, but should be ok for everything else, and if there is a short, it will limit the
current so there is no disaster. Then you can also see the current that each circuit draws on the charger ammeter and fuse it appropriately (I know
you can calculate it but it's nice to just confirm)
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DarrenW
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| posted on 16/5/05 at 03:55 PM |
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How many people have had major problems with new looms? What have been the main problems / root causes / corrective actions?
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NS Dev
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| posted on 17/5/05 at 02:33 PM |
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If you mean "new" as in scratch made to your own design from lengths of wire (which mine have all been) then not much really. Only one
mistake I can ever recall which was mixing up permanent and ign key controlled lives after I pulled the labels off then went for dinner. Didn't
cause a problem really, just had the wrong things key controlled and had to swap some spade terminals about.
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David Jenkins
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| posted on 17/5/05 at 02:52 PM |
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I designed my own loom, and still had a couple of fuses pop on initial testing! Purely caused by me not following my own wiring diagram properly.
I'd go with the "pull all the fuses and test each circuit individually" approach. This reduces everything to bite-size chunks that
can be managed easily. You will still have to test with all fuses in eventually, but at least you will know that almost all the wiring is good before
you start.
If you test one circuit and the fuse blows, you can work back from the load (light, motor, whatever) and re-check just one or two wires at a time.
Have fun!
David
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craig1410
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| posted on 18/5/05 at 08:57 PM |
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I built my own loom from scratch and everything was fine. I initially used a bench power supply with ammeter to allow me to monitor the current drain
while I powered up and tested each circuit. Everything worked fine first time I am glad to say.
Another tip I would suggest is not to bare any wires until you are ready to crimp them and make sure that you use female crimps on all feeds so that
in the event a crimp is disconnected from its mate it will be protected from shorting against the chassis. I'd also recommend using an old
headlight bulb for testing circuits that you don't really want to power up properly such as the fuel pump, radiator fan or horn.
Much more fun making your own loom than buying one in my opinion but not necessarily cheaper...
Cheers,
Craig.
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James
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| posted on 20/5/05 at 04:11 PM |
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quote:
Originally posted by craig1410
Another tip I would suggest is not to bare any wires until you are ready to crimp them and make sure that you use female crimps on all feeds so that
in the event a crimp is disconnected from its mate it will be protected from shorting against the chassis.
F"ck! What a good idea!
One that I know from doing other stuff and it didn't even cross my mind when I put a load of crimps on last night! 
Blast!
Oh well, out with the wire cutters again! 
Cheers,
James
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"The fight is won or lost far away from witnesses, behind the lines, in the gym and out there on the road, long before I dance under those lights."
- Muhammad Ali
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craig1410
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| posted on 22/5/05 at 09:13 PM |
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James,
It's only good practice, not essential because you should always isolate the battery when working on the electrics anyway. However, it is quite
reassuring when powering up one corner of the car at a time as I did, that the disconnected corners aren't as likely to go up in smoke....
Cheers,
Craig.
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clbarclay
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| posted on 22/5/05 at 09:44 PM |
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Or use connectors where both male and female terminals have an insulating shroud. More common with multi pin connetcors.
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