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V8 - fire!

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KV8
Posts: 304
Joined: Sun Mar 06, 2016 7:05 pm
Location: Cambridgeshire

V8 - fire!

Post by KV8 »

Hi
This afternoon I took my V8 for a drive as my strange engine problem has disappeared and I have found I think the source of the water leak.(another story!)

Noticed that steering (not PAS) appeared a bit heavy so when i got back I set to to check tyre pressures with cigar lighter plug in compressor (done this many times before). N/s front was rather low and a couple of others needed a small top up .

At the end of this procedure I found I could not withdraw plug from Cigar connector so waggled it a bit and it suddenly comes away. Instantly clouds of thick white smoke appear fom all dash and heater outlets. I pop bonnet. leap out and rapidly spin battery disconnector and smoke eventually clears.

Dropped the dashboard and expect to see smouldering heap of melted cables.

Surprisingly not so there are only 2/3 connections that show damage

Even then this is only for first few inches. the cigar lighter socket is a molten plastic mess at the rear but assume it had 2 terminals. The earth terminal and wiring is still intact apart from some "sweating" of insulation.

The leads to the Cigar lighter other contact appear to have been 1) a purple lead from wtihin a loom, (2) a spur to a terminal on the ignition swtich 3) a connection to a fabric covered lead disapearing into another loom.

Having extricated and taped all loose ends I reconnected the battery. As all seemed OK I turned on ignition and as all was well started the engine

Then found that everthing worked perfectly (Guages/lights/ wipers/washer/horn/fan etc.

Problem is I cannot view my DVD ROM manual as either it freezes whilst trying to diplay .pdf or my antivirus blocks the .exe. Worked Ok about 10 days ago!

So can someone please e-mail/pm the the wiring diagrams for both the V8 and V8 250 as my car has been converted to negative earth with a self regulating alternator

Many Thanks

H

Sydsmith
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Joined: Sun Feb 14, 2016 11:15 pm
Location: Aberystwyth Wales

Re: V8 - fire!

Post by Sydsmith »

H Most cigar lighter sockets are borderline heavy enough wired for some tyre pumps and I have had trouble with a modern Mercedes from the same thing, sounds like you are lucky and there is unlikely to be any damage further on.

My solution has been to cut off the cigar lighter adaptor from the pump fit a couple of crock clips and clip it direct to the battery.

Sorry dont have a wiring diagram for a V8 or 250.

KV8
Posts: 304
Joined: Sun Mar 06, 2016 7:05 pm
Location: Cambridgeshire

Re: V8 - fire!

Post by KV8 »

Sydsmith wrote:H Most cigar lighter sockets are borderline heavy enough wired for some tyre pumps and I have had trouble with a modern Mercedes from the same thing, sounds like you are lucky and there is unlikely to be any damage further on.

My solution has been to cut off the cigar lighter adaptor from the pump fit a couple of crock clips and clip it direct to the battery.

Sorry dont have a wiring diagram for a V8 or 250.
Thanks but I dont think this was anything to do with the load of using a tyrepump via this socket it could equally have been a phone charger. The pump was off and the plug jammed, I wiggled it to release and something broke in the base of the plug causing a short .

H

Petelang
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Location: Nottingham
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Re: V8 - fire!

Post by Petelang »

Cigar lighters should always be on a fused circuit. Hence the purple wire which denoted fused battery supply.
However, there should not have been a connection to the ignition switch and it sounds to me like someone before has made a silly alteration which has endangered the system by taking a non-fused supply off the ignition switch input side.
In the case of a short, the 35 amp fuse in the purple circuit should have saved the "smoke escaping" from the lucas electrical system!
When you fix it, trace the purple and make sure it's fused and connect nothing else to the cigar lighter.
Peter Langridge
Cloud Nine Classic Weddings, Nottingham.

johnwager
Posts: 74
Joined: Thu Feb 11, 2016 3:26 pm
Location: Thundersley, Essex

Re: V8 - fire!

Post by johnwager »

I can send you a wiring diagram via email for a 2.5 V8, and a V8 250.
Let me have your email address via PM
John

KV8
Posts: 304
Joined: Sun Mar 06, 2016 7:05 pm
Location: Cambridgeshire

Re: V8 - fire!

Post by KV8 »

Petelang wrote:Cigar lighters should always be on a fused circuit. Hence the purple wire which denoted fused battery supply.
However, there should not have been a connection to the ignition switch and it sounds to me like someone before has made a silly alteration which has endangered the system by taking a non-fused supply off the ignition switch input side.
In the case of a short, the 35 amp fuse in the purple circuit should have saved the "smoke escaping" from the lucas electrical system!
When you fix it, trace the purple and make sure it's fused and connect nothing else to the cigar lighter.
Hi firstly thanks to all - found a Jag mk2 diagram on line.

Petelang you are pretty well right.!
Investigation with circuit diagram shows that the cigar lighter should be common to the interior lights only and the 12V derived from the fused unit. However it is obvious that as you say some previous owner has derived the 12V for both the cigar lighter and the interior courtesy lamps from the positive feed to the ignition switch! The purple lead i have established using a meter is only for the courtesy lamps. On examination the positive feed to the ignition switch was charred along its visible length until it disappears into a loom.

Examination of the circuit diagram again shows this feed is derived from a common terminal on the (reduntant) ammeter. This I confirmed again with a DVM. Whilst the lead at the ammeter end shows signs of overheating it is still insulation intact. The lead from the ammeter to the starter solenoid shows no adverse signs. So can easily replace supply from ammeter to ign switch and can still derive interior courtesy lights from here ( but with in line fuse!) and can just leave cigar lighter ad ifinitum or untiil I chance on one on e-bay or at an autojumble.

However I still have the mystery of the fabric bound lead that was also connected to the cigar lighter. Since this is zero volts with ignition on or off and is not earthed and shows infuinite resistance to earth one can only assume that it is another botch 12V feed to a switch somewhere ....but as said everything seems to work !

This lead disappears into a wiring loom binding to the right of the meter/switch panel

Any Ideas

Thanks

H

PS tried loading DVD on a friends computer - would not load on there either. Its 20 months old but just noticed its a DVD-RW !!!!

I am a video buff and will investigate and hopefully get my £30 back from JHT!

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