The Triumph 2000/2500/2.5 Register Forum

What a plonker!
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Author:  badger [ Thu Sep 07, 2017 8:02 pm ]
Post subject:  What a plonker!

Tonight whilst playing with the electrics trying to solve a problem, I managed to connect a live feed wire from the n/s rear light to the earth side of the rear number plate bulb. The rear lights are now very dim. Anyone with a clue as to what I've done. Please help!!

Author:  johnconradlee [ Fri Sep 08, 2017 10:49 pm ]
Post subject:  Re: What a plonker!

Dim rear lights might mean you've done something to the night dimming relay if you haven't already disconnected it.

Author:  badger [ Sat Sep 09, 2017 4:18 pm ]
Post subject:  Re: What a plonker!

Thanks for the reply. The brake lights are also dim too. Whereabouts is the relay?

Author:  badger [ Sat Sep 09, 2017 4:25 pm ]
Post subject:  Re: What a plonker!

Aha, after reading another post, it's in the boot. Thanks for your help. I will update tomorrow after I've "played " with it.

Author:  Alan Chatterton [ Sat Sep 09, 2017 4:33 pm ]
Post subject:  What a plonker!

It's behind the n/s boot hinge. Pull off the black Earth wire to bypass it and all should be well.

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Author:  badger [ Sun Sep 10, 2017 3:02 pm ]
Post subject:  Re: What a plonker!

Blast, the lights are still dim, any other suggestions please?

Author:  Alec [ Mon Sep 11, 2017 6:59 am ]
Post subject:  Re: What a plonker!

Hello Badger,

you may have overheated a connection, you'll need to look at areas like the light switch, there should be visible darkening if that's happened. Alternatively use a multimeter if you have one to check any terminations from source back to the lamp. If the earth point is common to the numberplate lamp and the rear lights then check that also.


Author:  Tinsmith_Skippy [ Tue Sep 12, 2017 6:34 am ]
Post subject:  Re: What a plonker!

Sounds like the night dimmer has latched on to me, if the obvious is not the battery. On the night dimmer try disconnecting the green and purple wires and temporarily bridge them then disconnect the earth and bridge it onto the body. Then that might indicate a faulty relay. However the fault could be at the switch end if there is corrosion bridging the park light and side light position. Best I can come up with.

Author:  Mike Stevens [ Wed Sep 13, 2017 3:09 pm ]
Post subject:  Re: What a plonker!

Disconnecting the earth wire only stops the Night Dimming Relay operating in dim mode. I suspect that you have seriously damaged its inner workings so the best solution is to remove it and bridge the relevant wires. That's what I have done. The simplest way is to get some 'Lucar' double males (1/4" tabs) to bridge the wires. There are 3 or 4 of them to bridge, but use a circuit diagram to work our which wire colour goes to which. Make sure everything is suitably insulated when you have finished!

The Night Dimming Relay doesn't do any thing useful really, so its removal is probably the best solution in the long run.

Good luck!


Author:  Alec [ Wed Sep 13, 2017 6:08 pm ]
Post subject:  Re: What a plonker!

Hello Mike,

correct me if I am wrong but surely the night dimming relay only dimmed the brake and indicator lamps, not the tail lights?

I still feel that the extra current drawn by shorting the circuit to earth overheated an already marginal termination and made that worse?


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