LS - 1st and 2nd Gen (1990-2000) Discussion topics related to the 1990 - 2000 Lexus LS400

Radio/Nav unit reboots

Old 06-16-14, 09:54 PM
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aptoslexus
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Default Radio/Nav unit reboots

I've got a 98 with the Navigation. The radio/nav unit has developed a weird problem where it reboots about every minute or so. It's as if you turned the key on and off, except the engine is unaffected. The radio goes out for a second while it restarts. It takes about 5 miles of driving in the morning before it starts doing it, but it does it every day. Oddly, on the drive home after work, it begins sooner, maybe a couple minutes into the drive. Seems to continue for about 15 minutes, after which it will stop and operate normally. Maybe that last part is why I'm really scratching my head. Anyone have any ideas as to what would be the problem?
Old 06-17-14, 06:33 AM
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sha4000
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Probably something temperature related in the head unit. How long has it been happening?
Old 06-17-14, 07:31 AM
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It's been going on about a week or so.
Old 06-17-14, 07:32 AM
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Yamae
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Did you check the ACC voltage at the radio/nav unit?

Is it keeping higher than 11.5V while the engine is on?
When the ACC voltage is dropped and then going up, the radio/ nav unit is reset automatically. We call it a power-on-reset. When the supplied voltage is too low and then going up higher than the limit, the reset circuit works and generates the reset pulse.

I suggest you to check the voltage while driving setting up a voltage meter and see the voltage. If it's going down and up, check connections.

If the voltage is good, then you need to check the reset circuit, but this needs some technical skills.
Old 06-17-14, 07:53 AM
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Originally Posted by Yamae
Did you check the ACC voltage at the radio/nav unit?

Is it keeping higher than 11.5V while the engine is on?
When the ACC voltage is dropped and then going up, the radio/ nav unit is reset automatically. We call it a power-on-reset. When the supplied voltage is too low and then going up higher than the limit, the reset circuit works and generates the reset pulse.

I suggest you to check the voltage while driving setting up a voltage meter and see the voltage. If it's going down and up, check connections.

If the voltage is good, then you need to check the reset circuit, but this needs some technical skills.
Yeah, I was thinking there was a voltage drop going on. Prior to the reboot problem, the display would sometimes suddenly dim, then get brighter.
Old 03-21-19, 08:19 PM
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Just tying up an old thread. I lived with this weird snafu for years. The reboot would trigger at a certain location, the same location every time, but would be fine elsewhere. Then recently I noticed that it would reboot if I tried to set "home" on the navigation unit. That made me suspicious of the hard drive unit in the trunk, so I bought one on Ebay and swapped out the drive. Problem solved. I assume some location data became corrupted on the disk.
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