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2006-2009 Range Rover MkIII / L322
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Discussion Starter #1
Our 2006 HSE 4.4 is experiencing a failure within the MOST loop which is causing the "A/V OFF" display, intermittent audio drop (every 15 seconds or so), and flashing orange light on the head unit power button each time the audio cuts out.

Thanks to this forum and its members (you've saved me thousands of dollars and many trips to the shop with your excellent insight over the years), I've done the following to try and fix this problem, but as of tonight... I'm stumped!

*Had battery & alternator checked. Came back clear.
*Checked fuses for radio/nav/DVD, front & back. All good.
*Checked for any sign of water intrusion in the rear left boot. Nothing noticeable.
*Did a hard reset by disconnecting battery. Audio drop still there.
*Isolated each component I could get access to in the rear boot by pulling fiber optic cables and using pen housing to point them toward each other. "A/V OFF" and audio drop persisted with each unit isolated. Orange light kept flashing every 15 seconds with amp isolated.
*I did the self-test you access through the NAV screen, and it came up with some error codes (MOST Status "Unlock Critical", B100E25, B101025). Please see the two pictures I've attached, as it looks like the MOST loop is corrupt somewhere.

This audio issue has persisted for three months. One interesting note: The audio issue stopped for 3 hours (200 miles of highway driving) immediately after our L322 was jump-started by another car. It worked perfectly, but as soon as I turned the car off and restarted 10 minutes later, the audio started dropping out again.

I would love to avoid going to the dealership for guidance, and thank you in advance for any advice as to what I should investigate next.


RR MOST Fault 2.jpg RR MOST Fault 1.jpg
 

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JACK'S GRANDAD
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9,242 Posts
Re: "A/V OFF", MOST Loop Failure, Intermittent Audio

Not knowing where you took it to get the battery and alternator checked, I dont trust it.
It takes only a few minutes to run through the electrical sticky yourself.
Do that then post the results.
And if the rig was running when the the test was being done on the A/V, and it was showing 13 volts as a system voltage, something is wrong with the battery, alternator, or wiring. The fact it acted normal after a jump start enforces that too.
Do the sticky, then report back with the results. I'm guessing at a voltage/ground issue.

Martin
 

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2006-2009 Range Rover MkIII / L322
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Discussion Starter #3
Re: "A/V OFF", MOST Loop Failure, Intermittent Audio

Thanks for your time and your response Martin. I will check that this week, as I have a multimeter on order from Amazon.

Fully realizing this information isn't as "good", I got a reading of 13.8 V at the front cigarette lighter last night with the RR running, idle, and no load. It was 13.8 V at 2000 RPM with no load, dropped to 13.6 V at 2000 RPM with a full load, and the reading with the engine off after 30 seconds of a full load was 12.2 volts.

I will post the electrical sticky results this week.


Paul
 

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2002-2005 Range Rover MkIII / L322
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1,947 Posts
Re: "A/V OFF", MOST Loop Failure, Intermittent Audio

if your system running voltage is 13.5 to 14.2 then its a safe bet your charging system is working as it should .

NOTE when it drops below 13.4 running at 1500 RPM,
thats when the voltage is not sufficient to charge the battery and it will have a slow drain this usually indicates a bad diode.

NOTE a bad diode comes from being jump started or hooked up to a hi powered battery charger.
NOTE worn brushes can also damage the diodes as they cut off then come back on,
so the regulator should be checked for worn brushes
 
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