Subject: Re: [TR] TR2-3 electrical melt downs

From: bill beecher <[email-masked]>
Date: Tue, 23 Jun 2020 08:52:53 -0500

Have a friend with a TR6 that had a significant meltdown behind the dash.  I should think, given the right set of weaknesses, most any section could melt. 
Bill B

Serenity Now......

On Jun 23, 2020, at 4:52 AM, Tom Householder <[email-masked]> wrote:

Over the years I have experienced and seen harness melt down in the looms to the tail lights .. anyone ever had an under dash melt down?

Trying to answer a question asked of me. 

Tom 
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From: "dave" <[email-masked]>
Date: Tue, 23 Jun 2020 08:59:46 -0500

OK.  This is a TR6

Friend had a wiper switch go bad, constantly supplying power to the wiper motor, which was stuck.  He had the power on in the car (not running) chasing some other electrical issues.  Melted some insulation under the dash before the fuse blew

---

From: John Linney <[email-masked]>
Date: Tue, 23 Jun 2020 07:22:24 -0700

I had my ignition pilot light wire melt down when it shorted to the indicator lamp assembly which had fallen out of its broken holder. I just had to replace the wire from the ignition switch to the pilot. Happened at the end of my street.

> On Jun 23, 2020, at 2:52 AM, Tom Householder <[email-masked]> wrote:
> 
> Unsubscribe/Manage: http://autox.team.net/mailman/options/triumphs/[email-masked]
>

---

From: DAVID MASSEY <[email-masked]>
Date: Wed, 24 Jun 2020 14:37:56 +0000 (UTC)

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 Keep in mind that these wire harnesses, like the car as a whole, was desig=
ned to a budget.=C2=A0 These harnesses had three (count 'em, 3) fuses.=C2=
=A0 As such some items were unfused like the headlamps and the coil.=C2=A0 =
And those things that are fused shared a fuse so the fuse had to be sized t=
o carry the current for everything on that circuit.=C2=A0 But the wires wer=
e sized for the particular load.=C2=A0 A thinner wire will have a nigher re=
sistance and under=C2=A0 short-circuit conditions the current can be limite=
d to a level that will not blow the fuse but the current will cause enough =
heating to cause the insulation to melt.
Another factor against us is the age of the harness.=C2=A0 The connector co=
ntacts get corroded and will get hot under normal circumstances.=C2=A0 Wire=
 strands can fatigue and break within the insulation again resulting in ove=
rheating under normal use.=C2=A0 The insulation gets stiff and cracks expos=
ing the wires within.=C2=A0 Lots of potential failure modes here.=C2=A0=20

Compare this design to those found in modern cars you will see dozens of fu=
ses.=C2=A0 Sure there are a lot more electrical items but most things have =
their own fuses.=C2=A0 This means you can size the fuse more appropriately =
for the wire used to power that device.=C2=A0 Also the connectors used are =
water tight and don't corrode as quickly.=C2=A0 Also, they are, on the whol=
e, a lot younger and therefore retain more of their original integrety.
But a fresh works well enough so if you fear a melt-down a new harness may =
be a good investment.
=20
Dave=20

=20
=20
-----Original Message-----
From: bill beecher <[email-masked]>
To: Tom Householder <[email-masked]>
Cc: [email-masked] daily digest <[email-masked]>; FOT Lis=
t <[email-masked]>
Sent: Tue, Jun 23, 2020 8:52 am
Subject: Re: [TR] TR2-3 electrical melt downs

Have a friend with a TR6 that had a significant meltdown behind the dash.=
=C2=A0 I should think, given the right set of weaknesses, most any section =
could melt.=20
Bill B

Serenity Now......

On Jun 23, 2020, at 4:52 AM, Tom Householder <[email-masked]> wrot=
e:

=EF=BB=BFOver the years I have experienced and seen harness melt down in th=
e looms to the tail lights .. anyone ever had an under dash melt down?

Trying to answer a question asked of me.=20

Tom=20

Archive: http://www.team.net/pipermail/triumphs  http://www.team.net/archiv=
e

[email-masked]

Archive: http://www.team.net/pipermail/triumphs  http://www.team.net/archiv=
e

[email-masked]

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<div style=3D"color:black;font: 12pt Arial, Helvetica, sans-serif;">
<div> <font size=3D"3">Keep in mind that these wire harnesses, like the car=
 as a whole, was designed to a budget.&nbsp; These harnesses had three (cou=
nt 'em, 3) fuses.&nbsp; As such some items were unfused like the headlamps =
and the coil.&nbsp; And those things that are fused shared a fuse so the fu=
se had to be sized to carry the current for everything on that circuit.&nbs=
p; But the wires were sized for the particular load.&nbsp; A thinner wire w=
ill have a nigher resistance and under&nbsp; short-circuit conditions the c=
urrent can be limited to a level that will not blow the fuse but the curren=
t will cause enough heating to cause the insulation to melt.</font></div>

<div><font size=3D"3"><br>
</font></div>

<div><font size=3D"3">Another factor against us is the age of the harness.&=
nbsp; The connector contacts get corroded and will get hot under normal cir=
cumstances.&nbsp; Wire strands can fatigue and break within the insulation =
again resulting in overheating under normal use.&nbsp; The insulation gets =
stiff and cracks exposing the wires within.&nbsp; Lots of potential failure=
 modes here.&nbsp; <br>
</font></div>

<div><font size=3D"3"><br>
</font></div>

<div><font size=3D"3">Compare this design to those found in modern cars you=
 will see dozens of fuses.&nbsp; Sure there are a lot more electrical items=
 but most things have their own fuses.&nbsp; This means you can size the fu=
se more appropriately for the wire used to power that device.&nbsp; Also th=
e connectors used are water tight and don't corrode as quickly.&nbsp; Also,=
 they are, on the whole, a lot younger and therefore retain more of their o=
riginal integrety.</font></div>

<div><br>
</div>

<div><font size=3D"3">But a fresh works well enough so if you fear a melt-d=
own a new harness may be a good investment.</font><br>
</div>

<div> <br>
</div>

<div style=3D"clear:both"><font size=3D"4">Dave </font><br>
<br>
</div>

<div> <br>
</div>

<div> <br>
</div>

<div style=3D"font-family:arial,helvetica;font-size:10pt;color:black">-----=
Original Message-----<br>
From: bill beecher &lt;[email-masked]&gt;<br>
To: Tom Householder &lt;[email-masked]&gt;<br>
Cc: [email-masked] daily digest &lt;[email-masked]&gt;; F=
OT List &lt;[email-masked]&gt;<br>
Sent: Tue, Jun 23, 2020 8:52 am<br>
Subject: Re: [TR] TR2-3 electrical melt downs<br>
<br>

<div dir=3D"ltr">Have a friend with a TR6 that had a significant meltdown b=
ehind the dash.&nbsp; I should think, given the right set of weaknesses, mo=
st any section could melt. <br clear=3D"none">Bill B<br clear=3D"none"><br =
clear=3D"none">Serenity Now......<br clear=3D"none"><br clear=3D"none">On J=
un 23, 2020, at 4:52 AM, Tom Householder &lt;<a shape=3D"rect" ymailto=3D"m=
ailto:[email-masked]" href=3D"mailto:[email-masked]">trho=
[email-masked]</a>&gt; wrote:<br clear=3D"none"><br clear=3D"none">=EF=
=BB=BFOver the years I have experienced and seen harness melt down in the l=
ooms to the tail lights .. anyone ever had an under dash melt down?<br clea=
r=3D"none"><br clear=3D"none">Trying to answer a question asked of me. <br =
clear=3D"none"><br clear=3D"none">Tom <br clear=3D"none">** <a shape=3D"rec=
t" ymailto=3D"mailto:[email-masked]" href=3D"mailto:triumphs@autox=
.team.net">[email-masked]</a> **<br clear=3D"none"><br clear=3D"no=
ne">Donate: <a shape=3D"rect" href=3D"http://www.team.net/donate.html" targ=
et=3D"_blank">http://www.team.net/donate.html</a><br clear=3D"none">Archive=
: <a shape=3D"rect" href=3D"http://www.team.net/pipermail/triumphs" target=
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