Hey guys haven't made a post in a long time or ever not sure, I've had my 91 for a year and it's had this one intermittent electrical issue since I got the car it hasn't really gotten any worse but i wanna know how to fix it,
symptoms:
coolant light, e break light, tail light light, oil light and maybe one other, will post pictures when I'm at the car later, I've been told possible a bad ground or alternate issue but I've had the car for a year and my alternator seems fine, these lights don't stay on they flash when it seems my batterys at low charge and then when that happens sometimes my sound system cuts out and my headlights dim and what not, clearly an electrical issue just want to know how to get to the bottom of it.
and now just yesterday I turned my car off and my passenger turning signals stayed on solid not flashing and I didn't have the car on or keys in at all and I couldn't turn them off at all, finally battery died while trying to fix it, jumped the car got it running around and everything was working fine until I parked the car again the sane issue happen, possible trunk wiring harness? Has anyone had these issues? Some help would be greatly appreciated, 275k kms 1991 Lexus ls400

 

Judging from your symptoms, I suspect that the ignition switch or the related line is causing the problem because those dash lights and the turn signal are getting power from IG1 which is one side of the ignition switch.

I'd check the resistance between the battery terminal + and the fuse named "TURN" after removing the battery's negative cable as well as turning the ignition switch ON. It should be almost 0.0 ohm every time you turn the ignition switch ON. If it's not 0 and shows some resistance, the switch or the line may be the cause of the problem. The line includes a bigger fuse named "AM".