Screen intereference.

BarryM · #1 09-25-2013, 03:45 AM

I've just upgraded to a MK IV nav unit in my 2002 E39 and now I'm getting screen intereference once the engine is turned on (it's fine with no engine)....
the interference shows up on the nav screen but also on the radio screen. The screen also flickers briefly as the door closes (so guess that's as the interior lights are sent a signal as well).

The MK III was clear and all I've done is swap the unit so 2 block connectors and the thin silver cable, I'm guessing it's a shielding problem but can't think why it would show up just with this swap as all the cables are the same.

I'd been looking forward to getting this as it should also speed up my Intravee screen refresh but a bit frustrated right now so any suggestions gratefully received.

TerminatorX5 · #2 09-25-2013, 09:15 AM

So, when you place the previous module back in place and reconnect, the interference is gone? usually i would suspect wiring - the interference from the engine running probably comes from the alternator (if you have the whine on sound lines) and from other radio-emmitting devices (there are plenty of those in the back of the car). The interference is a result of poor shielding, as you have correctly noted...

if the MK3 has no interference and MK4 has it - the issue could be in the inside circuitry of the MK4...

if the MK3 did not have issues, then the MK4 got the issues and when you put the MK3 back, the issue is still there, then you need to look into the wiring harness, you may have a chaffed/nicked/detached ground wire somewhere (ground wires are chocolate-brown).

Barry, welcome to the forum... it seems that you have an E39, as you mentioned but it is always nice to know more details of the ride and the option packages that you have for a proper suggestion... since your location does not tell us if you are driving a US spec or EU spec car, a signature line might be helpful...

BarryM · #3 09-25-2013, 10:02 AM

HI TerminatorX5, I appreciate your reply and they were my general thoughts but it's always good to get a second opinion - I'll report back.

I will also add a signature for future reference, have spent a lot of time trawling the nav threads which are very useful.

My car is a UK model Alpina B10 V8 4.6 so the electrics should be basically the same as a bog standard E39 although it has the 'dreaded' DSP and I've also installed an intravee with a lumidock.

BarryM · #4 09-25-2013, 03:51 PM

I've just tried swapping back the MK III nav and now have interference with that but I might have jumped the gun earlier.

It seems that the interference happens when the car is moved/moving and the screen flickers and the colours change as well, but it's not dependant on the engine running.

The only thing I did when fitting the new nav was to swap over the 2 connectors and co-ax cable so wondering if maybe the connectors into the back of the unit might have worn a bit giving some movement so that any vibration from the car is causing a slightly bad connection and causing the flicker - does this sound possible and if so any suggestion how to fix it?

TerminatorX5 · #5 09-25-2013, 07:34 PM

flicker and the change of color - chaffed/corroded wires in the RGB lines... I don't have time to look it up at this moment, but if you search the forum for the pinout of the navigation wires, you can see which wires are for the Red, Blue and Green feeds... check those wires, they are definitely loose...

BarryM · #6 09-26-2013, 06:59 AM

Thanks for the pointer, I'll be running a search shortly!

BarryM · #7 09-27-2013, 07:18 PM

Flicker gone after checking the wiring and realising that my half installed wireless reversing camera was still connected, removed it and hey presto clear screen!

When I swapped nav units I must have pulled or caught one of those wires which did something.

TerminatorX5 · #8 09-27-2013, 07:31 PM

Glad that it worked out for you.