slowsc430

I have done a lot of research on this forum regarding issues with the ML stereo having no sound...on my 02 sc430...i was driving on a sort of bumpy road and listening to radio last night and all of a sudden it has no sound.

i got a lot of info in the forum and what i have checked so far are:

there's nav sound

everything on the stereo works except no sound

i can adjust asl, bass, fade, etc etc all that

all fuses are okay

i took out the amp the nav would go out...i plug the amp back in the nav would work fine


any clue what may be wrong here? the head unit itself?

thanks
ricky

VVTiBob

1st question...after turning on the head unit and selecting a FM source, does the antenna function (goes up) and selecting the CD source does the antenna retracts completely? Trying to determine if the signal wire is working, it signals the antenna and the amp when the unit is turned on.
2nd question do you have a volt ohm meter to test the cable for signals from the head unit to the amp (test at the 25 pin amp connector)

VVTiBob

There are two connectors to the amp dealing with sound ...S22 and S23. S23 is a 25 pin connector and S22 should be a 16 pin connector.
On S23 pins 24, 12, 23 and 11 should be left and right channels and colors G, R, (left - and left +) and W, Blk (right - and right +) respectively. For orientation Pin 1 on the S23 connector should be a blue wire with a black stripe. Pin 25 should be empty.

GS4_Fiend

iTrader: (22)

Do that check above. If you got power, most likely, amp is going out.

slowsc430

hi,

antenna functions correctly...

i ll try to get a meter to test the cable tomorrow...

thank you very much.

ser67

If you're incredibly lucky its just a loose connector - but more likely to be that your ML amp is on the fritz - you'll probably notice that your battery also gets drained because the power-amp refuses to switch itself off.

Feel the temperature of it first thing in the morning - mine was scorching in spite of the car not having turned a wheel in 12 hours.

Get a re-conditioned one from ebay (about $350) and put it in yourself - the only hard job is pulling the boot apart !

VVTiBob

With the antenna functioning properly the chances of it being the head unit are very slim. So it probably is the amp based on the info supplied so far.
Ser67 brings up a good point, but only one possibility. Nevertheless, since you already have the trunk apart checking the temperature of the amp is easy to do. If it's warmer than room temp there's a problem with the amp shutting off. If it's not the problem may still with the components. Unfortunately I do not have a schematic for the amp itself.

slowsc430

I finally have more time last nite to work on the problem
I see that when I play am radio the antenna will go to highest
When I play fm radio the antenna will retract about half
But when I play cd the antenna state the same as fm radio
This is not normal ? It should retract all the way in ?

I also checked the amp it's normal temperature but when I turn on Navi and radio, the little cooling fan on the side doesnt turn at all . Is this normal ?

I m scratching my head now @.@

ser67

The little fan is almost certainly on a thermostat or similar (temperature probe and electronics these days probably).

Amps get hotter when they are working more - so pumping out the sound will cause the fan to come on as the temperature increases.

No sound - No heat. So that could be one explanation why the fan isn't coming on.

You can get the head unit to do a self test to see what error codes are coming up so it will may you which part(s) may have failed.

If you look at one the pictures I attached you can clearly see the display, head unit, and Gateway (hub) are all fine but the AMP is not sending a reply - so is dead.

I've also attached the service menu 'hack' you need to do to get into it.

Would also be worth checking your ML Amp serial/model number to see if it was one of a dodgy batch Lexus installed.

VVTiBob

Just a reminder. When you are in the built in diagnostic mode. The speaker output from the amp is shut off (no sound).

slowsc430

thanks for the reply and information....i will look into it once i have time tonight.

thanks again
ricky

slowsc430

Hi,

i did a service chek this morning on the navi,
my screen is the almost the same as your attached photo on your screen

Fr-DISPLAY: CHEK AUDIO H/U: CHEK NAVI-ECU: CHEK
G/W-ECU : OK DSP AMP : NCON

and the part number on the amp is 86280-0W070

does it mean i have a dead AMP and everything else is ok?

thanks for all the help
ricky

VVTiBob

Regrettably, yes. Did you get the error code definitions I emailed to you?

ser67

Go to ebay to find it - don't pay more than $350 for one.

Get the vendor to photo the bar code with model number and made sure that its one of the revised parts starting '74##' - you don't want it to go again.

See the picture I attached for details.

slowsc430

thank you guys for all the help. =)

time to spend some money looking for a used amp @.@