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 Post subject: Blown fuse.
PostPosted: Thu Jun 17, 2021 9:20 pm 
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Presently suffering a blown fuse issue on my Sprint.

I have read several of the previous threads relating to similar issues so know it could be a variety of problems. However any thoughts welcome.

The problem is the top fuse. Tried three new ones, with all blowing immediately.

Today I took both the purple wires off and then placed them back on individually. One was fine, but the other when re-connected blew the fuse immediately. The one I have now disconnected I know powers the clock as that has stopped working. I do however have all instruments on the dash working including the rev counter. The purple wire from the loom I have left connected to the fuse box seems fine with no issues.

Can anyone suggest what could be run off the purple loom live that powers the clock that I should pay special attention too. The overdrive is an obvious candidate as the cause. Any other suggestions very welcome.

Cheers

Richard.

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Sprint, ;- DBL 532V


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 Post subject: Re: Blown fuse.
PostPosted: Thu Jun 17, 2021 9:51 pm 
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Joined: Sun Aug 21, 2011 5:12 pm
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Location: Highley, Shropshire
Purple wires are fused permanent live, so you can forget anything ignition controlled like overdrive, instruments, wipers, washers, indicators and brake lights.

What you are looking at is clock, interior lights (including the boot light) horns, headlamp flash and cigarette lighter.

With the lead that doesn't blow the fuse connected, try the horn, if that works you can eliminate it and also the headlamp flash that runs off the same wire as the horn.

Which leaves the clock, interior lights and fag lighter. If I was a betting man, i'd put my money on the fag lighter, pull the element out and try connecting again with a new fuse.

Steve

_________________
'73 2 door Toledo with Vauxhall Carlton 2.0 8v engine (The Carledo)
'78 Sprint Auto with Vauxhall Omega 2.2 16v engine (The Dolomega)
'72 Triumph 1500FWD in Slate Grey, Now with RWD and Carledo powertrain!

Maverick Triumph, Servicing, Repairs, Electrical, Recomissioning, MOT prep, Trackerjack brake fitting service.
Apprentice served Triumph Specialist for 50 years. PM for more info or quotes.


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 Post subject: Re: Blown fuse.
PostPosted: Thu Jun 17, 2021 10:19 pm 
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Cheers Steve that narrows it down.

I have read clocks and fag lighters can be troublesome.

I will eliminate tomorrow what you suggest and come back with an update.

Hopefully it will be a simple fix.

Cheers

Richard.

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Sprint, ;- DBL 532V


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 Post subject: Re: Blown fuse.
PostPosted: Thu Jun 17, 2021 11:35 pm 
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Location: Highley, Shropshire
The fag lighter is also the easiest thing to access, might be worth pulling the purple wire off the back of it too, to eliminate a possible short in the unit itself.

To access the clock you have to remove the glovebox, the boot light is easy enough but you have to hang upside down under the parcel tray inside the boot with the boot lip digging in your ribs. This gets harder as you age, as i've learned. Don't worry about the earthing switch, which is by the O/S boot hinge mount, if it's duff the boot light either won't work or will stay on perpetually. It might run the battery down, but it won't blow a fuse.

Worst of all is the interior light, it runs down both A pillars and across the roof behind the headliner, it's a nightmare to work on, pray it's not that at fault! But you can disconnect it for test purposes, theres a plug for a single purple wire on the N/S A pillar near where it meets the dash/bulkhead. Disconnect this and you've pulled power from the entire interior light circuit that you can't reach!

Steve

_________________
'73 2 door Toledo with Vauxhall Carlton 2.0 8v engine (The Carledo)
'78 Sprint Auto with Vauxhall Omega 2.2 16v engine (The Dolomega)
'72 Triumph 1500FWD in Slate Grey, Now with RWD and Carledo powertrain!

Maverick Triumph, Servicing, Repairs, Electrical, Recomissioning, MOT prep, Trackerjack brake fitting service.
Apprentice served Triumph Specialist for 50 years. PM for more info or quotes.


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 Post subject: Re: Blown fuse.
PostPosted: Fri Jun 18, 2021 3:55 pm 
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Hi Steve.

Today carried out the suggestions starting with the fag lighter. Took it apart, isolated it, but the fuse still blew. Not the fag lighter.

Took the glove box out and isolated the clock, test it but the fuse still blew. Put it back together and the glove box back in.

Traced the boot light and inspected the wiring. The bulb holder had no bulb in but again cleaned connections up, tested it the fuse blew again.

Tested the interior light. Disconnected it and tried another new fuse, but the fuse blew. Lastly I disconnected the purple interior light wire at the n/s/f that feeds all the interior lights, again tested with a new fuse but the fuse blew when completely disconnected at the loom joining point.

Sort of ran out of ideas at the moment so any new ones would be very welcome.

Will mentioned when rebuilding her he had issues with the same fuse blowing relating to the overdrive. He throughly insulated the wires through the gear stick which all looks spot on. As you say the purple wires are a continuous live feed so I am stuck for ideas.

Cheers

Richard.


Image

Image

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 Post subject: Re: Blown fuse.
PostPosted: Fri Jun 18, 2021 4:08 pm 
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Hi Richard

Have you traced the wire to make sure it’s not shorting out on anything?

John

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1972 Dolomite 1850


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 Post subject: Re: Blown fuse.
PostPosted: Fri Jun 18, 2021 4:11 pm 
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Hi Richard, Looking at the number of fuses you have got through, I had exactly the same problem on my 1850.
Here are my findings, in 2 places !

https://forum.triumphdolomite.co.uk/vie ... ck#p321075

HTH,
Tony.


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 Post subject: Re: Blown fuse.
PostPosted: Fri Jun 18, 2021 4:43 pm 
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One suggestion, couldn't you use the continuity checker on a multi-meter to check for shorts, instead of installing a fuse? It would save you a lot of blown fuses.


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 Post subject: Re: Blown fuse.
PostPosted: Fri Jun 18, 2021 5:44 pm 
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Cheers guys.

I can trace from the fuse box into the main loom which is all good.

I had a good look around when the glove box was out and see nothing that caught my eye. As Steve suggested I disconnected the purple wire at the N/S/F connector and tested which eliminated all the interior lights from that point back. I did not test the front door switches that turn on the interior light but I assumed the passenger side would be disconnected anyway, which only leaves the drivers door.

When I disconnected all the interior lighting the fuse still blew.

The fault therefore I assume must be in the loom between the fuse box and the front bulkhead as the interior lighting was disconnected at the N/S/F connector.

Are the hazards on that purple fuse line as I did not check them or the wiring connected to the switch ??

It was fine until two weeks ago, blew a couple of times but accepted a new fuse and all was fine. Now just blows immediately .

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Sprint, ;- DBL 532V


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 Post subject: Re: Blown fuse.
PostPosted: Fri Jun 18, 2021 10:35 pm 
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TDC Shropshire Area Organiser

Joined: Sun Aug 21, 2011 5:12 pm
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Location: Highley, Shropshire
I rechecked my wiring diagram for the last model cars after seeing it was Will's (ex Jon Tilson) 1979 car

Nothing came up any different but the hazard flasher unit, which is behind the dash, is also fed from that fused purple wire as you surmised.

Yuo can try disconnecting the purple wire from the hazard flasher unit, purely for the sake of elimination, but i'd be surprised if that circuit is the cause.

The purple wire feeding the interior light goes only from the connector you've isolated to the lamp itself, all the others going to the post switces FROM the lamp are effectively earth wires and won't blow the fuse, just put the light on, so you can discount those.

So you are now surely in the realm of looms. First, isolate the front to back loom by disconnecting the 9 pin multiplug which feeds it, it's right by the plug for the interior lamp by the N/S "A" pillar. Only the boot light wire runs through this loom, but it runs through some out of the way spots with possibilities of burning from welding repairs around the rear wheel arch and long term exposure to water and boot (shoe type boot) scuffing in the footwells. I've seen all these in my time, so worth a check!

Also emphatically worth checking that collector point in the main loom Tony pictured and it's associated metal P clip, also the clock bracket he mentioned (I had trouble with this on my own car, but the majority of Sprints have a different clock attachment that doesn't have that metal U bracket, just a harmless plastic ring.)

Whilst in that area, check the loom extension that feeds the clock, fag lighter and heater fan switch that you can see on the right side of Tony's pic and make sure it hasn't got trapped or rubbed whilst fitting the parcel tray. The parcel tray is a be-atch to fit and easy to trap things trying to screw invisible screws into inaccessible spots.

If all else fails, you'll just have to carefully chase the path of the main loom as it runs from A post to other A post, under the heater etc and visually inspect for anomalies. Not much fun to do and I'd suggest, probably only possible to do rigorously with the parcel tray out and other vent clobber removed from under the heater box.

Steve

_________________
'73 2 door Toledo with Vauxhall Carlton 2.0 8v engine (The Carledo)
'78 Sprint Auto with Vauxhall Omega 2.2 16v engine (The Dolomega)
'72 Triumph 1500FWD in Slate Grey, Now with RWD and Carledo powertrain!

Maverick Triumph, Servicing, Repairs, Electrical, Recomissioning, MOT prep, Trackerjack brake fitting service.
Apprentice served Triumph Specialist for 50 years. PM for more info or quotes.


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 Post subject: Re: Blown fuse.
PostPosted: Fri Jun 18, 2021 11:28 pm 
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Cheers Steve.

Sounds like a nightmare and a right pain in the rear to sort.

I will run a check on the hazards but if that fails I will begin looking for the proverbial needle in a haystack which I know will be painful.

Old electrics are certainly testing !!!

_________________
Sprint, ;- DBL 532V


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 Post subject: Re: Blown fuse.
PostPosted: Sat Jun 19, 2021 12:35 am 
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Joined: Sun Aug 21, 2011 5:12 pm
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Location: Highley, Shropshire
Quote:
Cheers Steve.

Sounds like a nightmare and a right pain in the rear to sort.

I will run a check on the hazards but if that fails I will begin looking for the proverbial needle in a haystack which I know will be painful.

Old electrics are certainly testing !!!
Well, once you get into problems with the main loom it can tax your patience a bit! To be fair, even on old cars like ours with electrical transmission by the "prince of darkness" Joe Lucas, these problems are remarkably rare. Just your bad luck to have found one!

More often than not (and i'm decidedly NOT pointing a finger at Will or anyone else in particular) they are down to operator or mechanic error rather than an intrinsic fault in the system. It's sadly true that most people have trouble making a tidy job of fitting a simple stereo, let alone anything more complicated.

I can completely remove and refit a main loom to a Dolomite in less than half a day, without reference to a wiring diagram. But i've done a "few" and Lucas colour codes are etched on my subconscious. And unlike most mechanics, I actually enjoy car wiring!

Just as well really as I get involved in some spectacularly convoluted jobs sometimes, my current "Project Dolomega" Vauxhall Omega powered Sprint auto has 3 discrete looms, 2 fuse boxes containing a total of 23 fuses and 14 relays, ECUs for engine AND transmission, "fly by wire" throttle and lots more electrickery. It keeps me out of the pub!

If you were a bit closer, i'd pop over and fix it for you.

Steve

_________________
'73 2 door Toledo with Vauxhall Carlton 2.0 8v engine (The Carledo)
'78 Sprint Auto with Vauxhall Omega 2.2 16v engine (The Dolomega)
'72 Triumph 1500FWD in Slate Grey, Now with RWD and Carledo powertrain!

Maverick Triumph, Servicing, Repairs, Electrical, Recomissioning, MOT prep, Trackerjack brake fitting service.
Apprentice served Triumph Specialist for 50 years. PM for more info or quotes.


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 Post subject: Re: Blown fuse.
PostPosted: Sat Jun 19, 2021 12:56 pm 
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Just for the record, Wills work is impeccable and spot on.

He did a fantastic job with the car, and we speak quite often. It’s great having Will on the end of the phone as he is a top bloke.

It’s just one of those things. I will find it, but may take a few goes. Checked out the main culprits so at least I am getting through the elimination process. It’s also very helpful having members share their own troubles and advice.

What else are Sunday mornings for ?? Head under a dash with a screw driver in your mouth and a torch in hand. It’s part of the enjoyment 😊

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Sprint, ;- DBL 532V


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 Post subject: Re: Blown fuse.
PostPosted: Sun Jun 20, 2021 12:23 pm 
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Hi Richard, There is another possibility.
First do the hooters work ?
If they do please ignore this.

If they don't then the possibility is the fault is in the stalk to the hooter, but for a subtle reason.

When Triumph used the Lucas stalk for the hooter function I reckon the original intention was to put +12V on the + side of the hooters and then operate them by switching the - side of the hooters to earth. ( Like the MGB wiring. ) Now Triumph wanted to do things differently so they applied continuos +12V to the hooter switch and arranged that the switched side of the supply was wired to the + side of the hooters and they then earthed the - side of the hooters.
The way Lucas did this hooter switch was to make the stalk of an aluminium tube, covered by a plastic outer sleeve. An earthing wire was run up the centre of the tube to the press-switch on the end. In the Triumph case this aluminium tube actually is live to 12V, so if it gets earthed accidentally you have a short circuit from 12V to earth. If you pull the lighting stalk connector at the base of the steering column that should prove it.
Tony.


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 Post subject: Re: Blown fuse.
PostPosted: Sun Jun 20, 2021 6:34 pm 
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Hi Tony.

The hooter is all good and on the other line which is not blowing so that’s all good.

As Steve pointed out and I read the manual, it’s one of four things with the fifth being a break in the wire somewhere. The wiring diagram even I can read thankfully. I will check the wires to the hazards as I have not looked at these yet.

I will trace it this week and let you know what it was.

I took my ten year old daughter out today for a ride. She reports back she is not impressed with 1970s engineering, bless her.

Cheers.

_________________
Sprint, ;- DBL 532V


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