Weird issue with blinking gear indicators

[Stampeed Valkyrie]

08 SR5 V6 Auto. I have noticed lately that the AT gear indicator will pulse/blink when I turn off the headlights.

When the lights on its normal, when I turn the lights off D,N,1,2.. etc all blink.
If I turn the lights back on.. normal.. off again and it starts back up.

No codes, no other warning lights. No slipping or other issues.

Its about due for a Transmission service, was waiting for the crappy NE winter to end before I go under and drop the pan, and filter.

Any ideas?

 

[Squarecat]

Went searching for an answer for this same issue and this was the first result. Too bad there isn’t an answer yet (unlike for almost every other question I’ve had for 4.5 years of ownership!)

Funny enough mine is also an ‘08 SR5 V6 4WD (just over 214k miles). I didn’t think to check the other gear positions when I noticed the issue last night in Park. Same thing with headlights: pulsing while off, no pulsing when on.

I’m just assuming it’s a voltage issue or the bulb is starting to go, which would be a pain. So happens that I just replaced one burnt out incandescent running light with LED (which I’ve had for a while after the other side went out—no I didn’t change both at the time) but that’s almost certainly pure coincidence.

GIF of the pulse:
https://imgur.com/gallery/4th-gen-4runner-pulsing-gear-indicator-backlight-RCySii4

 

[kodenco]

Do either of you have LED bulbs? Certain cheap LEDs without proper shielding can cause all sorts of backfeed into the electrical system, causing weird issues like this.

 

[Squarecat]

Do either of you have LED bulbs? Certain cheap LEDs without proper shielding can cause all sorts of backfeed into the electrical system, causing weird issues like this.

That very thing occurred to me because, as I mentioned, I happened to have just installed one LED running light. However it was the second one installed—I’ve had another one in for a long while now. Besides which, they’re off when the pulsing occurs. (Edit: they’re both Sylvania from retail blister packs. No LED headlights or other new bulbs.)

I’ll add that I have the Voltage Booster PRO that tricks the alternator into outputting more voltage for an AGM battery. It’s set to Low for a very moderate bump. I also have a bluetooth battery monitor (which I just realized hasn’t connected recently.) That was all done about 2.5 years ago when I put the battery in and has caused no issues.

I’m not inclined to think any of that is directly attributable to this but I’m not going to rule anything out at this point. I’m hoping someone has already either figured this out previously, or we have an electrical wizard in our midst. I’m leaning towards an emergent alternator failure and I may try temporarily swap the Voltage Booster out just because it’s easy and see what happens.

Thanks for any insight anyone might offer!

 

[Nightmarejuice]

Would this back feed damage any sensitive components?