[DeTomaso] Electrical Issues AGAIN

[Phil Lockett]

I concur with all the preceding answers, this is definitely an earth problem.
Back in the dark ages when I ran Mini Marcos' - which are totally glassfibre, with only front and rear subframes for earth, this was an almost permanent problem - One time the right turn signal made the heater turn on slow, and pushing the horn made it go faster - It is all down to the electricity finding the easiest way to earth - which if there is no direct route will go back up the loom and through another circuit to find it.
I've even had the starter motor earth through the speedo cable which wasn't good.
I ended up fitting a small copper buzzbar from a 400v motor control panel under the dash which sorted most of it.

Basically you need to disconnect all earths, give them a quick wire brushing, and reconnect - I usually give them a touch of copper grease too.
But also, have a good looksee to find if any of the earths have been forgotten completely and not reconnected, but also that the wires haven't snapped inside the insulation just before they go into the ring connectors.

FWIW early minis had the same problem with the hazard light switches. The thing being that the switch needs to disconnect the normal turn signals and connect the hazards all in one movement - and with a mini, all without relays. The fix is the same, jumper the two wires that feed the turn signals together to bypass the switching mechanism for the hazards.