audio volume turns off after a few mins

[paulvasey]

hi guys, i have a 2003 l322 range rover ( x5 in disguise ) the prob i have is after a few minutes the audio turns off. if i push the button and turn off then back on ,it comes back on for another few minutes, then back off again. this just continues , on ,off,on ,off always for the exact amount of time? can anyone point me in the right direction? thanks in advance

[paulvasey]

thought id better say , it has mk3 nav, m54 radio, tv tuner and dsp and the fault is accompanied with any others

[Brian-bmw]

Is this what you are experiencing? Is your nav screen dead? Did you replace the DSP amp?
Troubleshooting blank nav screen and radio shut off

[paulvasey]

interesting link but no my nav works fine and the dsp is original, but the link suggests the nav maybe the problem, if noone can come up with an answer i may remove the nav unit and see if it still happens. i believe audio still works when you remove the nav unit?

[Brian-bmw]

The problem is that the DSP amp is not communicating with other components it needs to see on the car's I-Bus. If your nav is working normally and the radio functions are normal (other than the shut-off) then you have a mystery. Does the volume control work, either on the dash or steering wheel?

The other potential cause is a failing battery. How old is your battery? I have seen this symptom first-hand when my battery neared its end of life.

[paulvasey]

radio and cd work fine volume works on head unit and steering wheel and the battery is is 2 months old , tested is today at 12.75v so bugger!?

[paulvasey]

am i right in saying i can take out the nav and audio should still work? or will the dsp recognise it as missing and shut down?

[Brian-bmw]

Yes, the audio will work with the nav system removed. However it will do what yours is already doing-- shut off after a couple minutes.

I am thinking that your amp needs recoding. Or your amp simply went bad.

[paulvasey]

do you think its deff the dsp? or could it be the mb54?

[Brian-bmw]

Go back to the root cause: The DSP amp will shut itself off if it does not see either the DSP controller (separate controller, nav computer, or MID, depending on the car's configuration) or the radio over the car's I-Bus. This can be for several reasons:

1) Radio module disconnected
2) Nav computer disconnected or faulty
3) I-Bus fault
4) Amp coded for non-nav in a car with nav or TV (or vise versa)
5) Low battery that degrades module performance and causes unrelated symptoms
6) Internal module fault that affects I-bus communications

Since the screen works, your radio station changes, and volume works, etc. you can rule out any major module failures like #1, #2, or #3. Since this is the only symptom you mention on the I-Bus, you can probably also rule out a general I-Bus fault like #4. You say your battery is new, so that potentially rules out #5.

That leaves an internal fault in a component that allows all other functions to work but I-Bus communications related to component presence (#6). This is a very low probability, so I would go back to #4 or #5 as more likely.