Triumph GT6 MKIII Electrical Faults

[NDP]

Hopefully I have come to the right section. I am the chap who posted the "Ground Points" request in the wrong section and once again sorry for any upset caused. Anyway the replies were very useful and I have tracked them down, cleaned the terminals and reconnected them. I have found that it has made sod all difference to my problems but hay-ho at least I can discount any grounding issues!

My problem is that my dip flasher, horn, radio and internal courtesy lights will not work. I did track down a blown fuse and replaced it but that didn't solve issues and neither did refreshing all the ground contacts as listed above.

I have a wiring diagram and an original 3 fuse (all 35amp), fuse box. At some point in its past history I did have the wiring loom replaced (about 25 years ago). All has worked reasonably well since then but I have had a quick look at the back of the fuse box and some of the terminals do not appear to have been used. I suppose a shot of the rear of one of these with the correct way to wire it up wouldn't go amiss if anyone has such a photo?

Any suggestions welcome, thank you.

[dougbgt6]

N,

The fuse box is a poor design, the clips at either end of the fuse are not attached to each other top and bottom. They rely on the fuse ends to connect with each other. This can give perplexing faults, the fuse may be held at one end, but only the upper or lower clip makes contact at the other end. Take out the fuses and squeeze the clips to get a little extra grip. 

Here is a diagram from the Triumphspitefire.com site. It's for a USA GT6 and there are some differences and errors, the fuses are misnamed, but colour makes it very easy to follow.

From what you say it sounds like the purple fuse is the culprit! 

 

 

 

Here is a famous thread on here regarding fuse box replacement, there are pictures of the old box which may be of help.

 

 

Doug

[chrishawley]

Problems with these fuse boxes far from uncommon.

Leaving the radio feed out of the consideration for the moment: The dip flasher, horn and roof light are all fed from the same fuse so a single problem at the fuse is probably more likely than three separate problems. Which fuse? It'll be the one getting unswitched live from the starter solenoid terminal which in practice means the one with a single brown feed on the back which goes 'out' through four purples.

I could suggest a couple of rough and ready ways to investigate. One is simply to remove fuse, clean up terminals and the scrunch in some baking foil where the terminals are then replace fuse. The extra bulk and conduction may tickle the connections back into action.  Or: Take a fly lead directly for battery positive terminal and connect directly to the 'out' side of the fuse and see if the circuits in question are now active. No harm in doing this since this fuse is unswitched in any case.

If these tests produce zilch then check that the 'in' side of the fuse block (for the fuse in question)  is getting 12v via the brown (multlmeter easiest but bulb test also fine of course). If no voltage then there could be a 'hard break' in the brown wire or a failed connection at the solenoid.The male spade terminals on the soleniod can with time loosen and break off.

That's hardly a comprehensive plan of investigation but it covers some common scenarios.

One other tip is that typical unbranded fuses have metal end caps which are about 1mm smaller diameter than original Lucas fuses so make a less decisive connection in the fuse box. If poss getting some OE Lucas can be helpful.

I'm not sure why the radio is dead as well. The radio feed should be on an entirely different circuit (unfused and switched off the back of the ignition switch in position 2. So might be simpler to leave radio out of the equation until dip flasher, horn and roof light are sorted.

[NonMember]

8 hours ago, chrishawley said:

The radio feed should be on an entirely different circuit

That very much depends on the radio. A lot of "modern" radio units are designed to have a permanent power feed (off the purple wire!) and use the accessory terminal on the ignition switch only as a wake-up input.

[NDP]

Well chaps many thanks for all the input and suggestions. I did the following:

1). Cleaned up all ground connections. (no effect)

2). Replaced any poor looking joints in wiring. (no effect).

3). Dis assembled the fuse box and re-assembled it so that it matched the American wiring diagram above (complete with incorrect top, middle and bottom fuse connections). Bingo! The dip switch, interior light and radio are now working. The horn is still dead so I will keep searching for issues with that (it may be a faulty part).

 

Once again thank you for all your inputs.

 

Happy motoring! Cheers.

 

[Clive]

Horn on the wheel? Lots of possibilities there! Check teh horn themselves work, I think (but check) all triumphs have a perm live feed to the horn, and earth back to the hornpush, a sprung "pencil" behind, onto a brass ring. Then rely on a jump wire over the original bottom steering joint, and teh rack being earthed via a braided connector. 

[NonMember]

8 minutes ago, clive said:

all triumphs have a perm live feed to the horn, and earth back to the hornpush

Not quite.

The ones with the horn on the wheel all have the horn push to earth. However, Spitfires and GT6s use that to drive a relay, the contacts of which switch the live feed to the horns, which have a permanent earth.

Later cars (Dolomites, Mk2 saloons, possibly late 1500 Spitfires?) are wired with a live feed to the column stalk, then to the horns, which have permanent earth.

[Badwolf]

I had a horn problem and ended up having to strip down the horn units and clean off the internal corrosion.  Yes, you can repair them. Connect each one directly to the battery to see if they work.  Bullet or other connections under the bonnet are highly suspect. Get someone to try the horn and listen to see if you can hear the relay activating mine did and that was the give-a-way for me that the fault was under the bonnet

[Pbruce9393]

Hi Guys,

You recently pointed me in the direction of the 3-way fuse box to cure my non-operational gauges. A clean & squeeze of the "green" fuse clips did the trick, but now I am faced with the rear lights not working along with some odd intermittent faults. While trying to track this down, I witnessed the middle fuse glowing red when the headlights were switched on, and smoke emanating from the fuse box.  Time for a new fuse box !!!  I have read the other articles relating to fuse box upgrades, and have a 10 way one ready to install, but I have one question I need help with.

As the new box has a single busbar for the 12V feed, is there any reason for the permanent 12V any more ? I assume it was previously required for the parking lights, but can the green & purple circuits from the above diagram be served from the same ignition controlled feed & distributed through teh same fuse box ? 

The red would need to have it's own fuse (in-line ??) and teh white ignition wires connected together, but is there any reason this would not work ??

Thanks

Peter

[NonMember]

No, you can't just replace the split circuit with a single feed. Some of the circuits you want to protect need to be ignition switched, and some of them need to be permanently live. Side (parking) lights are required to be available without ignition on by law.