Triumph Spitfire MKIV earth points

[ScottMk]

Hi all,

i have had a search on here and so far am coming up blank, both the books I have also do not show the earthing position on the Spitfire. 
 

I found out this week that if I have the headlights on and indicate left i get the fast flashing on the indicator, To me this is a bad earth somewhere. 
 

If anyone knows of all the positions and could share them that would be great. 
 

Scott

[NonMember]

Is it only with headlights or does it happen when on sidelights only? The most common cause of dodgy indicator earths would be one of the light fittings, both of which are shared with sidelights. The front fitting should be earthed by a wire to the main harness connectors in the centre of the bonnet front. The rear ones, on a MkIV, have a wire in the loom with a ring terminal that should be fitted to one of the mounting studs, although the bulb holders are available with individual earth tabs (the contact with the housing is often very poor) that will likely be daisy-chained from that if present.

[ScottMk]

1 minute ago, NonMember said:

Is it only with headlights or does it happen when on sidelights only? The most common cause of dodgy indicator earths would be one of the light fittings, both of which are shared with sidelights. The front fitting should be earthed by a wire to the main harness connectors in the centre of the bonnet front. The rear ones, on a MkIV, have a wire in the loom with a ring terminal that should be fitted to one of the mounting studs, although the bulb holders are available with individual earth tabs (the contact with the housing is often very poor) that will likely be daisy-chained from that if present.

Hi the indicators work fine with the side lights one. I’ll have a look where you said and do some continuity checks on the wiring

[Clive]

14 hours ago, ScottMk said:

Hi the indicators work fine with the side lights one. I’ll have a look where you said and do some continuity checks on the wiring

Beware, continuity checks with a meter can be misleading (I have a T shirt for that) as poor connections can give continuity with very low currents, but fail when even 1amp flows.

A 21w tester bulb connected to the battery positive, and a probe (nail/needle wrapped in tape will do) will draw enough current, and can be used to test the earthing of the bulb holders etc. At least that was what I used.

[NonMember]

1 hour ago, clive said:

Beware, continuity checks with a meter can be misleading (I have a T shirt for that) as poor connections can give continuity with very low currents,

Also, a multimeter used for continuity will generally regard a couple of ohms as "good continuity" but at 21W it's a third of your voltage and half your power lost.