Hi Everyone, Got two 3 litre MkII coupe's, one for spares/rebuild and the other on the road.
Every 20-30 seconds with the ignition on and when driving the electrical feed "blips" and short circuits for a second or less.The ammeter, lights, instruments and ignition system all momentarily "blip" then resume as normal. I,ve substituted battery, Dynamo, regulator and fuel pumps from the other car with no difference. The battery is charging well and generally has not been a problem - more an irritation that I need to fix.
The other unrelated electrical gremlin is that the tacho reads at double speed! - again this was the unit from the resto coupe which is only 6 chassis numbers away from the road car, should be a straight swap??
The final issue is that the loom colours have faded to such an extent that I have to check continuity on every wire to establish function.
Any bright ideas ?? (I don't want to do a complete rewire !)
Despite Phil's protestations...it can be reclaimed if you spent some time cleaning and redoing all the electrical connections. My MK3 still runs 90% of the original wiring plus additions for modern accessories.
* Clean all the fuse box connections plus the saddles each fuse sits in till they're bright and shiny. Dirt and patina over time in electrical connections creates high resistance.
* Release the instrument binnacle from the dash and check and retighten every connection to each switch.
* Ensure you check any/all wires coming off the generator and going to the regulator. Clean and retighten these.
* Carefully clean the points on the regulator bobbins if so fitted. Use very fine grit emory paper or wet and dry. Ensure there is no grit left between the contact surfaces.
* Clean to bare metal (don't be precious about paint where electrical connections are concerned) any and all ground connections...including the main ground from the engine to the front subframe and the subframe to the chassis body structure. The front subrame is mounted via 6 subframe isolators. Obviously these don't encourage a good electrical ground/earth connection.
* Spend the time doing the above methodically and you'll sort the issue.
Post by richardlamsdale on Mar 31, 2019 13:17:07 GMT
Just one thing to add - the ammeter will only deflect up if the short-circuit is occurring after the ammeter. It could also be a short in the main battery feed from the boot, and then the ammeter would drop to zero.
It could also be something simple like a loose connection at the battery or starter motor - maybe check those first as they're easy.