Earth point for rear lights?

[Ad2408]

Hello All

Can anyone confirm where the earth point for the rear lights are?

Seem to have a problem with the indicators and rear lights...

Thanks
Adam

[JohnD]

Adam,
The 'earth point' is the bodywork, where the light fitting touches it!

After years of corrision, made worse by alectrolysis between the steel and the non-ferrous metal of the light fittings, that this cheapo lash-up doesn't work well must be no surprise.  On the Herald and Vitesse, the two-piece body, rear tub and bulkhead, are seperated by webbing straps, and mounted on the chassis by rubber washers, so it's a surprise that it ever worked!

The cure may be thorough cleaning of the light fitting, both the contacts to the bulbs and where the fitting touches the body work, may help, but better is to rig an extra wire from the fitting's negative side back along the loom to where the battery is earthed or nearby.

   Do not rely on the thread of a bolt or self-tapping screw to make a good contact.  Make sure that the earth wire touches bare metal on the panel. Scrape off all paint around the hole, use some copper-grease which is conducting, to stop corrosion.
JOhn

[mjwman]

I have mine sorted after experiencing iffy operation. Usually at MOT time.

My fix was to solder an earth wire to each bulb holder.
These then end up connected firmly to the cluster mounting stud with a round terminal.

All has beeen perfect since and does not take long to do.

[rotoflex]

Assuming your 1971 Spitfire is sort of like my December 1971 GT6:

Starting at the bulb, the bulb (grounds, earths) to the brass contact in the bulb holder.
The the bulb holder (grounds, earths) via the springy things on the side of the bulb holder to the lamp unit.
Then the lamp unit(s) (ground(s), earth(s)) via some black wires that are gathered together at a screw on the bodywork.

A typical problem is an internal break resulting in the loss of connection from the springy things on the outside of the bulb holder to the brass contact on the inside of the holder which touches the bulb.  Check for continuity between those two points on the bulb holder.

If continuity is lost there, indicating a break, the solution is to repair or replace the bulb holder.

If replacing, beware:  some of the new bulb holders have been found to be poorly made and come apart the next time you remove the bulb holder from the lamp unit!

I fortunately got a batch of duff replacements from a great supplier, who when told of the problem, went through all he had on hand to find four good replacements to send me!

As for repairing, none of my internal soldering jobs inside the bulb holder lasted very long.  mjwman's idea of modifying the bulb holder by just soldering a long ground wire to the internal connection for the bulb is a good one!

[thescrapman]

The easy fix is to use bulb holders from a Mk2 2000, they have built in earth tags, so you just link them together and then to a decent earth point.

Cheers

Colin