I had the same issue. Resolved it by upgrading the battery cables. See.......I’ve been noticing that whenever I use my blinkers the voltage gauge needle also “blinks”, it will not do this with the flashers. So why would it do this? My truck is an ‘83, 5.3L vortec converted
All grounds were replaced with news ones when I resuscitated the truck about 6 months agoIts usually a bad earth , like 99% of the time. Its not normal in a landcruiser, its old age. The OEM earth cable on my 88 FJ73 was green from corrosion and the contact on the engine block was also corroded. The earth strap to the chassis also needs inspection/replacement.
All grounds were replaced with news ones when I resuscitated the truck about 6 months ago