none bike related electrical advice needed.

[dubber68]

A strange electrical fault has occurred on the other arfs 86 ford transit horsebox. The van will start but none of the lights etc work. The ignition barrel has been bypassed due to a knackered ignition switch but it ran happily like this for ages. Also the van will light up the alternator light and start on the button if the hazards, lights, or horn are on despite the 12v switch for ignition being in the off position. It's really got me scratching my head. I'm inclined towards a short somewhere from the post switch side of the 12v main wire. What do the wise folk on here think?

[Petethefeet]

Once fitted a single filament bulb to a brake and rear light on a Renault Scenic, the correct fitment was a dual filament bulb. The result of this was a car that did not turn off when the key was removed, giving all the signs of a bad earth. Took ages to sort after running alternative earth and cleaning contacts. The single contact on the bulb had bridged the two contacts in the holder giving very odd results.

[redbikejohn]

I wouldn't dream of looking at anything else until the ignition barrel had been replaced as that is a known fault. Once that is fixed then you can diagnose issues. Always fix a know fault as sometimes it throws up strange faults and readings.

[AlanHolt]

It could be so many things, but lets start by eliminating a bad earth as thats easy to do. If an earth wire is corroded or broken, the current will find a way to earth via another positive route, sometimes making lights flash when cranking the engine etc. So take a jump-lead and attach one end to the battery negative and the other to a clean part of the engine block. If that doesn't change the symptoms, move the jump-lead from the engine block to an unpainted bolt attached to the body somewhere.

[dubber68]

Well the problem is sorted. The mechanic who re-fitted the starter motor after checking it removed totally the earth strap. He said it didn't appear to be doing anything. WHY!!!!

[Richard Simpson Mark II]

I'm staggered!