Crazy electrical problems.

[zoidberg444]

I had some odd electrical gremlins when my alternator went bad - not as bad as yours but it was quite obvious the electrical system was experiencing a voltage drop. My voltage regulator was on the way out. This manifested in lights dimming and the engine acting strangely. I have seen plenty of videos on YouTube of mechanics in the US complaining most of the re-man parts like alternators and starters sold by the autoparts store are basically junk. I would probably find a genuine Toyota one from a scrapyard or order the Denso brand replacement.

If its not that - something this weird will probably be a ground issue or some wires shorted together somewhere - I would probably start looking through the wiring diagrams trying to find what they all have in common. These sorts of issues really are a pig to fix and you will probably end up having to have a professional diagnose it.

[06YarisRS]

Originally Posted by zoidberg444

I had some odd electrical gremlins when my alternator went bad - not as bad as yours but it was quite obvious the electrical system was experiencing a voltage drop. My voltage regulator was on the way out. This manifested in lights dimming and the engine acting strangely. I have seen plenty of videos on YouTube of mechanics in the US complaining most of the re-man parts like alternators and starters sold by the autoparts store are basically junk. I would probably find a genuine Toyota one from a scrapyard or order the Denso brand replacement.

If its not that - something this weird will probably be a ground issue or some wires shorted together somewhere - I would probably start looking through the wiring diagrams trying to find what they all have in common. These sorts of issues really are a pig to fix and you will probably end up having to have a professional diagnose it.

I suppose it could be a poorly remanufactured alternator. I've actually had great luck in the past with remans. I often buy older vehicles and the 3 - 4 alternators that I've replaced in the past decade have held up well. The last two, I bought from Carquest (the Canadian arm of Advance Auto Parts, I think) have been great. They told me they have a lifetime warranty. Many parts stores have alternator testing benches. The OP should be able to confirm whether it's good or bad fairly easily. I would get that tested and if it's good, do exactly what you say - start looking at the wiring schematics.