I installed LED's in my '94 ES and ran into a huge problem. I replaced the reverse lights, license plate lights, and both interior dome lights. Then I found out that my whole electrical system was malfunctioning. Only a few electrical things and lights worked at a time, which changed every time I tried the ignition, and the car won't start. Any ideas what happened, or how to fix/prevent it in the future?

 

LED's are polarized, try flipping the LED's around. Orrrr, LED's usually have a lower amperage, so if the parts you replaced with LED's are run by a relay the relay might not be detecting the LED's so you may need to change the relay to an electronic/digital one.

 

change everything back to stock and replace them again to LED one by one so you will know which one cause the problem

 

Your most likely problem is in the dome light area. You may have blown a fuse. Double check your dome light LED installation carefully and check the related fuse.

Phil