Ignition On Issue

[aerovolito]

88 Westy Diesel. Been standing (inside) for a year.

Battery's good. Van starts on the button and everything works as it should. However, when I turn the ignition on, it seems like I have a flat battery. The headlights are dim, wipers move slowly and horn doesn't work (I can hear the relay clicking). I removed and cleaned up the earth crowns - though there was minimal corrosion.

Have I missed something obvious?
 

[Rosie n' Jim]

My early van has a heavy wire running from the battery live to the fuse box. It carries the current for all the services, but with age builds up resistance. Check the voltage at the fuse box with everything off, then again with the ignition and headlights on. You'll probably be shocked by the drop.

[ZsZ]

On diesels the power goes to the fuse panel in a relatively thin red wire (6mm2) through the black box in the engine bay.
It has some crimps on it and there is a M6 stud junction in the box.
With time those connections can corrode and cause severe voltage drop.
Beside that the ground strap in the nose of the gearbox is a common issue to have bad connection.
It worth to elliminate it or at least add an extra ground strap somewhere between the engine block and the body.

[aerovolito]

Great suggestions, i'll try those. Thank you.

[aerovolito]

The fault was down to a bad earth from the gearbox to chassis. I rectified it and fitted an additional batt to body earth. Have good voltage all round now.