Random Electrical Failure - MK4 cossy cortina

could be the dash plug is loose or fallen out?
ST normaly keeps the origional loom for the rest of the car and just inserts the engine loom but obv i cant be certain as i didn't fit it?
try removing the fuse box and checking the pins under it and the plugs
As Mr scarey says speedo is usually cable unles the whole dash is granny as well

my mate had this with his capri and his alternator wires had melted on the exhaust. Pretty much the exact symptoms your mentioning. Didnt make sense at the time but ran new wires and it was fine

How do I do that? I presume I need a volt meter of some sort? So if the alternator is packed up it could be sending all sorts of wrong signals??

To make things more confusing.... On Tuesday night I disconnected the battery and left it like that for the whole of Wednesday in the hope it might “reset” something. When I got back home in the evening I thought I’d plug it all back in just to see if that had helped. Well the results were interesting indeed.........

So with the battery connected I put the key in the ignition. I turned the key only once to see if the ignition lights can on this time. They did!! (very weakly, but they did) This unfortunately was short lived. I started the car, nothing wrong there. As the car started the heater fan came on because I’d left it on the last time I was driving it (wasn’t working with the other electrical failures but now it was). I thought I’d really test this sudden turn around of life and try to use the indicators. As soon as I put the stalk down to the left, everything died!! Heater fan came to a standstill, rev counter dropped, fuel gauge fell, engine temp died. I also presume the brake lights have gone again as they must be on the same loop. I thought I’d then check the radio, tape of the commodores in (nice), and that works so I presume that its on a different loop.

Electrical things that don’t seem to work;
Rev counter
Fuel gauge
Brake lights
Indicators
Heater fan
Cooling fan (in front of radiator)

Electrical things that seem to still work;
Interior light
Hazard lights
Radio
Lights, front and rear
Dashboard lights
Rear window de-mister (that might actually not work but cant really tell this time of year)

I think that’s about it on the electrical side of things on a 78 Cortina

I’m getting proper stumped now? To make things worse I’m now getting to work on a bicycle and if that wasn’t bad enough even that broke on me today !!! Think I might just get a horse.

Hi Popuptoaster, without sounding too stupid, this electrical stuff is all new to me. where would the switch be? I have taken the trim off around the steering column and the carpet around the peddles but don’t really now what I’m looking for. Don’t suppose you have a diagram or something? I had a look at the back on the ignition barrel but there are just so many wires!!

^multimeter?

Poxy phone. Although if your hands are small enough to grab a millimeter I say go for go it.

Right got me a multimeter! I've had another thought about the "issue". The battery in the car is a pretty small one. It used to power the old 2.8 that was in there before with no issues. Now i've used the same battery in the car now and it has started first time, everytime. Its quite small (cant remember the size) and is probably not suitable for the 2.9 24v. Do you think that the alternator is putting too much power back to the tiny battery and its having to go elsewhere?

unfortunately my work comp wont let me see that link ^

I also don’t believe it could be that either as it has been working fine for about a month now. I think the alternator has either packed in or something more sinister has happened. Really struggling for ideas at the mo.

^ agreed.

I remember trying to fix my first car as it kept stalling for some reason. didnt know what it was so started buying new HT leads and all sorts. found the issue later and it turned out to be a worn point in the dizzy cap! lesson learned.