Melted Wire Casing under Dash - Help Appreciated!

[72BLUE]

Hi folks, my 'new' Stag needs its first repair after just 5 days

I pulled of sharpish this pm from the traffic light then seconds later lots of acrid smoke burst out from under steering column, pulled over and turned of, luckily nothing caught fire!

It turns out a wire to the radio feed has got very hot and the plasic casing has melted away for 6" or so from the (female side) of connector block. The corresponding wire on the male side of the connector block seems fine. I noted that another wire on the male side had worked out of the block, but this may have only happened when I split the block.

Be grateful for any input re the cause of the wire melting. Could it be the verdigris?

Many thanks to Bruce from Crewe for popping round to have a look at it and identifying the wires in question Great to meet you!

Photos attached of the block and wire which is just visible under dash by steering column with your head almost on the floor of the car..........

Cheers
Keith


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[V Mad]

Hi Keith
Usually this kind of damage is caused by a massive overload, or too much current flowing. But I notice the other white wire on the other side of the block is undamaged so it cant be an overload. The other cause of so much heat is a high resistance connection, and judging by the bad state of the terminals (verdigris etc), I would say that is the cause if the melted insulation. You will have to remove and replace all the bad wire, and clean up or replace the connector with a decent one.

[flying farmer]

I am not sure from the photo but is the wire to the connector thicker than the one on the way to the radio?
I had a massive short on the cigar lighter on the TR years ago due to the removable bit falling apart internally. It was fortunate that I had wired it in with too thin wire, as it set fire to the thin stuff, but the original loom was untouched due to the thicker gauge wire.
It looks rather like this is what has happened here, if it was just corrosion of the plug it would have melted both sides, just like on the TR (again), but this time on the main beam circuit
I would follow it all through to the radio, and fit a fuse in case it does it again!
Neil

[72BLUE]

Thanks for the input guys!

I think the side of the block that is OK comes direct from the ignition switch (male side). On the burnt out side the white/pink wire leads off, I think, to another connector block on the right side of the (manual) transmition tunnel. Will check it out.

I will also check tomorrow if the wire is same thicknesss either side of the block, although I do think it is.

My radio has a removable fascia which was not clipped FULLY on at time of melt-down, it clicks into place with lugs on the left and right sides. It is so awkward to clip on that I only released the clip on the left side so that the fascia is 'popped off' and sits proud on the left. To get the radio to work, I just push it on the left to clip it on. Perhaps this is a factor?

I think the radio does have its own inline fuse, although can't remember what Bruce said re this when he was having a look earlier today. Will check it.

The wire is definitely the power feed to my radio as Bruce has pulled out the good side (male) bullet connector from the block and my radio no longer works. Before he did this and with the damaged wire still in place, the radio did power up.

I do have a spare loom in my garage, so will try and swop the guilty part over, but I will check the connectors for verdigris, give them a clean and coat with a thin layer of vaseline.

In fact, I am going to check and clean as many of the barsteward connectors as I can find!!!!!!

Cheers
Keith

[Westfaling]

Keith
Important to remember that fuses protect from overcurrent not necessarily overheating caused by bad connections. I think your idea of checking all the connectors is wise.
This is the result of someone fitting fog lights to my car and fitting a bigger fuse. Lucky really that it didn't set fire to the car. I only had to replace the one wire!
Nick
Wiring.jpg

[72BLUE]

Thanks for that Nick. My problem is that I have never had a really good grasp of electrics! I would best describe it as 'basic'.

Still, we we see what tomorrow brings............

Cheers
Keith

[72BLUE]

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I have been out investigating today, rain now stopped play!

I have remembered something that may be significant?

Yesterday before the radio feed wire melted, I was trying to get the carpet to fit properly and spotted the wiring and connector blocks that are on the right of the gearbox tunnel behind the carpet (not visible on my photos, the connectors are just hidden below carpet). Anyway, I moved the connectors as I thought I was catching my left foot on them.

Could re-positioning the connectors and loom have caused a short? The burnt radio wire comes out of the loom in the area where I moved it, see photos.

Interestingly, or perhaps worryingly, the spare loom that came with the car has been partially unwrapped in the same area and has exactly the same white and pink radio wire missing and there are tell-tale burn/melt marks on adjacent wires................

Cheers
Keith

[Rubce]

Keith

One thing I did notice when I pulled the radio out is the fact that the cig lighter (with in-line fuseholder) was running off the same feed as the radio which is not as per the wiring diagram. I know you smoke, so did you use the cig lighter at the time of the incident?

Cheers

Bruce

[Westfaling]

Keith
Hard to judge but the photos you posted suggest to me that the overheating issue was more long term than instantaneous.
Nick

[72BLUE]

Hey Bruce, good lateral thinking there, but no, I have yet to try the cig lighter.

I am now thinking that the wire has shorted out by the RH gearbox tunnel area somehow. The burnt wire has some rough looking connections at its end as it led up to the actual radio units wire.

I will post a few pics later.

Cheers
Keith