Oona

I have a 1998 LS 400 with the premium Nakamichi cd and cassette player. When I accelerate and maintain constant speed, the stereo works perfectly. The tape, cd, radio all function. However, every time I slow down or stop, the stereo turns itself off! Once I accelerate it turns on again, then off again.. etc.

Anybody have any idea what’s going wrong with my stereo and or how to fix it? I want to keep the original stereo. It sounds fantastic for a car off its age. Thanks!

LeX2K

Could be a battery and/or alternator problem, voltage jumping up and down. Do you have a volt meter?

Oona

the battery is new, so I know it’s not that. I don’t have a volt meter. I was thinking a link or wire from the alternator too 🤔 but I’m not sure since the car runs smoothly.

LeX2K

Need to verify your voltage when driving one of these will do the job.

YODAONE

Are you referring to stereo in general.context to mean CD, Player, Cassette player and AM/FM Radio.. or just AM/FM stereo?

I have observed firsthand a 1998 LS400 with a dying alternator....the radio would go out first, then instrument cluster backlight.

Slowing down often requires using the brake pedal...which illuminates the brake lamps

Several power hungry incandescent bulbs in the taillight assemblies, including two T-5 bulbs in the third brake lamp....

When you are in park with engine running and apply the brake pedal, does the "stereo" turn off??

Another possibility is you have water sloshing around under the right seat where amplifier is located.

Have seen numerous LS400 with water under the seats with the amplifier mounting feet rusted away.

Check your negative battery cable grounding at fender well and AC Compressor stay.

Check negative grounds from engine block to chassis.

Check the integrity of postive battery terminal

Alternator tests are often free.

deanshark

When the alternator in my 93 was going bad I had the same problem with the radio shutting off when I hit the brake pedal. Plus all the lights on the dash would dim alot. Keep an eye on the dash lights when you drive and hit the brakes, see if they dim. The one light I noticed the most was the "D" for drive.
Also, go to Autozone, or wherever, and have them test the alternator.

Oona

So I took my vehicle to a mechanic shop for an alternator test. The test showed the alternator was working in overdrive due to a faulty battery. Fortunately I bought the 3 year warranty for the battery which I purchased last year. Their test confirmed it was defective. I got a new battery, my electrical motors are running faster (windows, moon roof, etc) and the stereo hasn’t turned itself off since. Crossing my fingers! 🤞🏼