Ignition short help

[AnD3rew]

Hi there

I have a short somewhere between the coil positive terminal and the ignition fuse behind the dashboard. The car cut out going over a speed bump at low speed. There was no power at the coil positive terminal. I found a blown fuse behind the dash and replaced it and checked the circuit and it was active again I started the car and it ran for about a minute and blew again.

Any advice on where to look first would be much appreciated, I am suspicions that there may be a worn wire somewhere and when the body flexed over the speed bump it moved and shorted.

[cactusman]

Hmmm....the feed.to the ignition is not actually fused according to the standard diagram as the white wire is connected to the ignition switched permanent live side of fuse 6 and seven....there are several white wires all connecting here...white is by convention ignition live but not fused.

Presumably someone has possibly moved your ignition feed to the other side of the fuse where there will be lots of green wires.....green is ignition live but now fuse protected.

So it may well be that another circuit fed from which ever fuse is now feeding your ignition has an issue.

Alternatively someone may have fitted a specific fuse just for your ignition....the coil feed white wire goes via the tachometer and through the main front loom to the coil so lol at the wires behind the tachometer and then follow the main engine loom ...it runs down the lhs footwell, through a big grommet into the engine compartment and then around the frames....look for damage....

[AnD3rew]

Hah, thanks, now I am very confused. Will try to follow it through.

[ralphr1780]

Check the ground strap body-engine is making good contact, this might be the origin of your issue.

[abowie]

Check the ground strap body-engine is making good contact, this might be the origin of your issue.

This is very sensible advice.

[AnD3rew]

Have narrowed it down a bit, the fuse that keeps blowing is the one for the tail lights and horn, the fuse is getting too hot to touch and then blows, and even when the fuse is intact the tail lights aren’t working. It also isn’t exciting the diodes to get the alternator working.

I can’t currently get in to check the earth strap, I can’t see it from above and my jack won’t get the car high enough to get far enough under to check it properly. Have checked what I can see of the brake light wiring and can’t seem to find any wearing or broken wires. But can’t see all of it.

[mgcjag]

Hi........you could use a multimeter to check continuity and resistance from battery neg to body.....fuse 5 should be for front/rear tail lamps and panel lamps and heated rear windscrean..fuse 3 & 6 for the horn...what model E are we looking at...your 69 S2 2+2..you could narrow things down by removeing all fuses.....get the car running then fitting one fuse at a time till problem....reoccours..Steve

[PeterCrespin]

Just clamp a jump lead from battery earth post to a head nut.