Mk2 Cortina lights and accessories stopped working

[PHLEX]

Hey guys!

Hoping somebody on here is familiar with Mk2 Cortinas and witchcraft

So recently got my Mk2 Cortina running properly which was down to carb and fouled plugs and I have noticed that now my lights, horn, wipers, blower fan and brake lights don't work. Nothing in the wiring has changed and I have bypassed the automatic circuit breaker I put in between the battery and interior feed and confirmed that's not at fault.

When the ignition is off I have a 12v at the power post of the ignition but as soon as I turn it to either acc or on theres no power at the main feed and also no power at either terminal. If I turn it to start I get power to starter terminal.   If I remove all the wires (4 on ON and 2 on ACC) but leave the main power attached I get 12V on both sets of terminals. I haven't tried attaching them one by one but I put a couple back on and found the switch appeared dead again.

Wiring was done by previous owner, few modified terminals and the switches for lights have been changed from a 3 terminal to a 2 terminal but bridged so if you switched the "instrument lights" on the parks came on and the "lighting switch" turned the main beams on. I will get a 3 pin switch and fix this but I don't believe this is causing my issue

Has anybody got any ideas? If I turn the car to start it will fire up and drives, the GEN light works (converted to alternator) but NOTHING else in the car works.  I managed to get the parks to dimly glow last night but nothing else was working. Each time I try something that doesn't change it I revert it back to how it was when it last ran properly as it would be very easy to mix wires up.

Thanks in advance!

[azzurro]

fuses?

ignition switch may have blown out esp if full load passes through it.

grounds grounds grounds

[PHLEX]

Thanks for the idea I did wonder about ignition being faulty, it's a replacement unit as the old one was flogged out. 

I checked every fuse last night and all had current passing through so I ruled that out but I'll have another check. I also just went and bought another universal fuse box and a few relays to take some load off the ignition itself as it's currently acting as a distribution block which surely can't be helping 

 

I will see if I can rule out the wires on the ignition one by one and find out what's causing the voltage to disappear because without any load it's got voltage on both sets of terminals 

[governorsam]

earth from the battery to the body. it looks like you have earthed the motor, but not motor to chassis. motor is rubber mounted, was probably earthing through the speedo cable or the choke cable.

[PHLEX]

I think you may be onto something there Governorsam as I have recently removed the choke cable from the motor and as its not currently being used and there's only the crappy factory earth strap that goes from the back of the motor to the body above the gearbox and it is the old mesh type and has been painted so I doubt its doing much.  Battery earth is currently just going to the engine mount. I shall go home and install a nice thick earth strap and report back.

Upon finding the aftermarket portions of the wiring behind the dash I went and purchased an aftermarket fuse box and some wire and terminals and I will tidy up a few of the wires that currently come off the ignition but I definitely want to make sure everything works before I start changing stuff!

 

Thanks heaps for the ideas, cant wait to get home and see if its just earths!!

[PHLEX]

Thank you both so very much! Earth was the issue, body to engine earth is stuffed and adding an earth fixed all my problems. Have been busy adding an interior fuse box to eliminate issues in the future.