Radio works only when headlight switch is on?

Hey all, interesting problem. 2018 Taco SR5, ACLB V6 auto. IT HAS THE MID-level Entune radio. A few weeks ago, the radio sound began to work only when the park or headlights are switched on. It functions just fine, just makes no sound unless the headlight switch is on.
I had it to the dealer, they charged me $150 for ‘diagnosing’ it, and found nothing. Then they said it’ll be $350 to diagnose the wiring, and there’s no guarantee. I have the Toyota Platinum warranty, but the dealer said they need to diag the cable, to see where the fault is, and if the problem is the radio, it may or may not be covered.
So, 500 bucks to hear that I may owe another grand? No bueno…

Has anyone else run into this problem? Thanks

 

How old is the battery? Did the dealer "load test" (opposed to "static test") the battery? Less power delivered makes circuits act cranky.

 

Pull the headunit out. If you haven't removed it before, the bezel just comes straight back with a firm grip and a good pull. The the headunit comes out by removing 4 10mm bolts. So as long as you can find your 10mm socket, you can have the radio out in a couple minutes. Then test for power to the back of the headunit . Make sure that you have constant 12v, Ignition 12v and Accessory 12v in all the right places.
Also check that you have a good ground as well.

The best way to test the deck is to try another unit and plug it in if you can get your hands on one.

 

Interesting comment about the battery. It is still the original, likely seven years old given that the truck was built in Jan of ‘18. The dealer did not mention a load test. You can’t get anywhere near the tech working on it.

As far as removing the head unit, I’m gonna wait till I hear back from the service desk at the dealer. I’d called Toyota’s main office, and spoke to a woman who basically said the same thing as one of the service writers.
I conducted a little test of my own. I sat in the truck, key on ACC. So the radio had power, but was off. With my cell phone close by, I called it with my land line. The radio answered the phone, but no sound, until I turned the headlights on.
So, I called the dealer’s service desk, and told the woman that I’d dealt with what I found. I reminded her that Toyota doesn’t need any more safety problems, and she then said to give her a day or two to investigate the possible safety issue.
I’ll wait to hear about her findings before I remove the radio and do my own diag.
Thanks for the responses!

 

AutoZone will load-test probably for free. Then you can buy a Duracell from them if you want. If you gave not purchased a

$100 NOCO GB40 1000A UltraSafe Car Battery Jump Starter, 12V Jump Starter Battery Pack, Battery Booster, Jump Box, Portable Charger and Jumper Cables for 6.0L Gasoline and 3.0L Diesel Engines

NOCO GB40 battery boost you should because any battery can die anytime regardless of age.

 

Radio gets juice from tail/headlight(and tail) circuit to dim the head unit illumination.

 

And that’s when the sound comes on. I should play with the instrument panel dimmer, see if the sound plays when the brightness changes state.

 

I'd say your head unit is kaput...

 

An excuse to get a new one.