Wiring Query 75 MGB Roadster

[Paul Scott]

Hi Everyone,

I'm after some info regarding 2 Green Wires located behind the centre consul where the cigarette lighter & Hazard switch should be. The Previous owner had blanked off the Hazard switch & although did not remove any wires joined a couple without cutting them off so the indicators worked.

So I have a new Switch, only to find the relay is broken, having dismantled it to work out what should happen one of the little tiny wires has snapped off the bi-metal strip.

In the same area I have two green wires with rubber covered spades on the end - they do look factory fitted. They also vanish into the wiring loom so they must be for something.

Does anyone know what they should be attached to?

There is no warning light for the hazards fitted, no Fog light fitted in the consul. Only a cigarette lighter which appears to be connected correctly and the interior light is attached & does work.

Hope you can help.

Thanks in advance Paul

[Michael Barclay]

Hello Paul
I think the 2 green wires you are referring to are for the heated rear screen on a GT. The same front wiring loom was fitted to both cars but as yours is a roadster they are not used. They reappear in the engine compartment in the bundle of bullet connectors below the fuse box.
Hope this helps.
Mike Barclay

[Paul Scott]

Thanks Mike,
Popping out around the fusebox will be most usefull. As I do need to ensure they are not connected to something else :-(

Regards
Paul

[Vic Butler]

Morning Paul.
Had a look on the wiring diagram for your car and there is one green wire on its own and a green and red/ brown wire. The red/brown wire is for the warning light and the green wire with it is the feed to the GT heated rear window via a relay. The single green wire is the power supply via an ignition controlled fuse.
Hope this helps.
. Vic Butler

[Paul Scott]

Thanks for the Info Vic,I will have another look tomorrow when I fit the new Hazard relay.

I will have the multimeter on hand to check the leads for switched power & hopefully trace them out.

Regards
Paul

[Paul Scott]

Hi Mike & Vic,
I have a green wire - live with ignition
Green Wire with a black ring on it - appears to do nothing - checked for power & to earth

I also have a chunky White wire with a green tracer line that appears to power up with the first turn of the ignition switch before the ignition warning light (second click).

I have now replaced the Hazard switch (missing) & (faulty) Relay so they al now work as should.

I will cap off the green wires with some insulated junction/connectors we use at work so they cannot touch anything. Cap off the chunky wire - unless you have any ideas where this should go.

Then pop it all back together - wait for the sunshine to appear and then I should be good to go - nearly. After I have fixed the leak from the Clutch slave cylinder.

Thanks again
Paul

[Michael Barclay]

Hi Paul
What you are seeing is correct. The green cones from the fuse box (3rd fuse down) and will be live with ignition on. If your car was a Gt it would have a switch and relay with indicator light to power the Green /Black tracer) .The Green/Black tracer wire then goes back to the bundle of bullet connectors by the fuse box. The would then be connected to the rear loom and rear screen. As your car is a roadster the switch ,relay and indicator light are not fitted. If you have a multi meter you should be able to select Ohms and place one lead on the Green /Black lead in the cockpit and you should be able to find the other end with a bullet connect attached in the bundle near the fuse box.
I used these wires to fit a manual over ride switch for the relay that operates my electric cooling fan.
Will check out the White /Green for when I am back from my business trip.
Hope this helps.
Mike Barclay

[Paul Scott]

Thanks Mike,
I did only have a quick look during my Lunch break today. No need for the heated rear screen on my roadster. Unless I need to push it.
I might have a use for those wires in future, but whilst I\'m in that area I will trace & mark the cables for future reference.
Thanks again for the info it is most usefull. I\'m going to make sure they cannot short out as that would be a disaster.
Kind Regards
Paul

[Vic Butler]

Evening Paul
Checked with the wiring diagram and as I thought the white and green wire is the feed for a radio. It runs off the auxiliary position on the ignition switch so that the radio can be on without the ignition system being activated. It's part of the wiring harness to enable the radio to be fitted easily.
. Vic Butler