melted wires

[dan]

A little while ago while trying to make my electrical system work properly on the 110 something happened and all the red wires melted. I haven't a clue why. Should I test the ignition switch and the light switch? Does any one know about testing the ignition switch? It is remotely possible that I may have switched 2 wires on the ignition switch. Are there any diagrams available depicting the wire hookup on the switch?

[DaveB]

I would start by checking the main positive wires going to the starter and the alternator. especially on some of the V8 models they have a tendency to jiggle too close to the exhaust, melt their insulation and short out. If the large wire shorts for just a few seconds, you'll often have other wires melted as well. Try and find the source of the short before turning the ignition on or trying to fire it up.
We had a Range Rover with this problem a couple of years ago on a run and ended up having to rewire the entire ignition and starting circuit on the side of the trail.

Dave

[ANDYD]

Also worth while checking your fuse ratings. In most cases the fuse is suppose to protect the wiring (from melt down).
I would recomend you check that all the fuses are sized according to the manual. I have seen 30A fuses where 5A fuses should be.
Once the fuses are all correct they should protect your wiring.

What recent work has been done on the wiring system that may of caused the short?

[Greg S]

Red wires are for the lighting components. Check beyond the light switch. The ignition switch should have nothing to do with it. Wires are shorted somewhere.

[Greg S]

I've loaded an article I wrote about early Land Rover wiring onto the Articles page of the Vancouver Island Website. www.vanislelandrovernetwork.com

Have a look, even though I don't think it will help in this case. You describe a short.

[dan]

I am finally closing in on my electrical problem. By the way, thanks all of you. In case that it wasn't mentioned, the truck is a 1986 110 exmod FFR. I went through the grounds on the front wings, as well as having a close look at the alternator and starter wirings. The browns coming out of the starter were in bad shape so I redid the contact. The insulation on the brown wires has become brittle. I may redo all the browns and any other suspicious looking wire.
Here is the breakthrough; I was testing the ground wires on the dash cluster and I got a current through the ground. I followed the bad ground, and found that there are two bad ground wires. One goes to the fuse box, and was hooked to one of those small golden coloured cubes behind the fuse box. It's about an inch x inch x inch and has four prongs on the bottom. There was a brown/white wire, 2 yellow whites and two white wires that went into it. What are these little boxes? Where can I get more? I am going back out to see where the other faulty ground goes.
Am I right in assuming these bad grounds are the culprits?

[ANDYD]

Hi Dan,

A bad ground (negative connection) will only stop things working, it wont be a dead short and melt wires.

If the browns are positive (12v) and are going to ground then that could be your dead short problem.

If , like you say you have current on a ground wire (how do you know it is a ground wire?) Then this also could be your problem.

The little 1" x 1" boxes are relays, do you have a owners manual? This would explain what each relay does.

good luck

Andy

[dan]

I tracked the second 'faulty ground' and it went to the relay inside the dash cluster. Andy you asked if the wires I was dealing with are grounds. With my limited knowledge,here's what I know; these wires are black, they have continuity with the frame, and they are joined together with other blacks. My best guess was that they are ground, or negative.
This is the test I performed; with a light tester, I turned on the ignition and tested the black wires hooked up to the relays. The light lit up. It did not light up with any other black wire. I also tested the other two relays and none of the black wires lit the tester up.

With regard to the melted wires, I forgot to say that I had hooked up the wiring for fog lights. I used a pick up point that comes from the light switch and contains the brown/blue/and red wires. I had inserted one prong of my fog light switch in the connecter that held the two red wires. I believe that this might have caused my red wires to melt although I can't really say.
With regard to these relays, why would they blow( is it related to the melting wires) and who sells them?
As always, all info is appreciated, cheers, Dan.

[ANDYD]

Hi Dan,

Did you use a relay when hooking up the Fog lights?
Because of the heavy load (amps) of most Fog / Spot / driving lights, the switch normally operates a relay which allows a higher gauge power souce to power up the lights. This prevents the heavy load passing through the switch and smaller wiring circuit.

Here's an example
http://www.classictruckshop.com/clubs/e ... glites.htm

cheers,
Andy

[dan]

Hi Andy, It did not even occur to me to use a relay. I had read up a little on them but it didn't dawn on me. I had only just run the wires without hooking the lights up. I had wired into a dash warning light( for some unused item) and then hooked the power to the switch , and hooked a wire to go to the fogs.That Bosch diagram is very usefull. I will be setting up my fogs the same way as on there. I noticed that the numbers on the bosch relay were identical to the ones I pulled out of the 110. Can I use the bosch relay? Will it fit the prongs on the truck?
What could cause the black wire coming out of a relay to dimly light the light tester when the ignition is turned on? When I touched the light tester to the black wire on both relays , I heard an audible click in them. The other2 relays didn't do this.
I've just done another test which confounds me even more. With one relay in place( and ignition set to ON) , I put the light tester on the black contact and the tester dimly lit up. I then removed the relay and fit it to the other relay plug and again tested the black wire but this time the tester did not light up at all. I tested three relays in the two adjacent plug -ins and each time the light tester lit up when the relay was in the one plug.
Regards, Dan.

[ANDYD]

Hi Dan,
If your relays have the same numbers and pin configuration as the Bosch then they should work fine. Are these relays original parts or have they been added after market. If factory installed, best to be safe I would stick to Land Rover parts. You should be able to get them from most of our local LR suppliers ( see the supporters link tab above).

Most relays have a coil which needs 12v and ground (negative) to energize, some are normally closed, (will open when energized) some are normally open (will close when energized) You can get various voltage feedback accross the coil which could explain your changing dimly lit bulb readings depending what is switched on or off including the ignition switch, some click when turned on (energized) some click when turned off.
You really need a wiring diagram to fault-find your issues.
If you wired your lights up without a relay its possible you have pulled 20-30amps through circuits that should only have 5amps (causing melt down of wires) Once the insulation on wiring has melted it can short in many other locations along its length.
This also makes me wonder why your fuses didn't blow to protect your small wiring.
Sounds like you will be busy sorting this one out!
All the best,
Andy

[dan]

I am stumped. On one of the relays in question( the one in the dash panel mounted to the bulkhead) there are 1 yellow/brown, 2 white/brown, 1 white and 1 black wire mounted to the relay plug. For those experienced with relays: brown/yellow goes to the 87 slot, brown/white to the 30 slot, white to the 85 slot and black(ground) to the 86 slot.
When the ignition switch is turned to the on position, the white wire is powered( it lights up the light tester brightly) and the black wire( ground) dimly lights up the light tester. Should the black wire do this? What am I missing?

[DaveB]

Does the specific relay you're talking about click when you turn on the ignition? If not, I would say your relay is pooched. I had one melt down on me in the closed position on the Northwest Challenge recently which resulted in the high-beam headlights staying constant on, but there are several ways they can short out inside. The relay you're talking about sounds like it's the common variety, so I'd just try a new relay in the spot before doing much else. Or pull one out next to it that's similar and try that first. The click is normally the easiest telltale whether it's working correctly.

Dave