Static, interference waves on Navigation Screen

[demens13]

Hello,

I recently hooked up a 2002 Matrix Nav in a 2008 Matrix. Everything works fine other then the screen.

It has these static, interference waves/lines on it. The lines get smaller with time and after about 20 min or so are almost not visible (but still there). Anyone ever dealt with something like this?

[fishexpo101]

2003 Matrix NAVI? There was no 2002 model year for the Matrix in the US.

As for the interference - sounds like a ground isolation issue in the screen, noisy power, and/or damaged LCD. Double check the chassis ground to the headunit and check for ground loops in the car.

For noisy power, most of that should be filtered out by the headunit - unless the noise is really excessive. You can find inline power filters that can help eliminate that noise. Can also be checked out by turning on the NAVI while the ignition it turned to ACC, basically running the NAVI off the battery.

As for an LCD issue - harder to check out. Assuming the donor car this NAVI unit came from, already verified that the unit worked perfectly there. Assuming that the install when pretty smoothly, if you had to force anything, there is a small chance that you twisted the LCD - that would cause all sorts of intermittent behavior/visual artifacts to pop up.

[demens13]

Thanks for the reply. Yes, you're right about 2003, its a typo. The screen still has interference even if key is only at ACC position.

Here are some pics of the screen and how it changes with time.

http://www.pixhost.org/show/2027/6269964_p1020346.jpg
http://www.pixhost.org/show/2027/6269965_p1020352.jpg
http://www.pixhost.org/show/2027/6269966_p1020347.jpg
http://www.pixhost.org/show/325/6269971_p1020351.jpg
http://www.pixhost.org/show/2027/6269968_p1020348.jpg
http://www.pixhost.org/show/2027/6269970_p1020350.jpg

[fishexpo101]

Thanks for posting the pics - that was quite helpful.

Definitely RF interference is causing those distortions - the trick is finding the source. Could be a ground loop issue, RF interference/noise on the power line, RF interference internal to the NAVI, or a bad LED display/driver.

Question: Does the distortion get any better/worse if you rev the gas pedal? Have you tried powering it straight from the battery?

I'd start with a quick visual inspection first - could be as simple as a loose connection on the back, or if you had to splice any wires, a bad connection / union between wires. Double check the plugs, make sure the pins on the headunit are not bent over or other wise damaged, same with the connector end - make sure the pins didn't push the terminators out of the connector. Look for obvious signs of wire damage - discoloration, damaged insulation, crushed wiring, etc.

If that doesn't turn up anything, then you have to start diagnosing the electricals. Easiest check is for the interference on the power. Try running it with the car running and the car off. If there is a significant change in the interference - likely you have power issues (ground loop, noisy power). After that, check chassis grounds, to see if there are any ground loops. If you have a voltmeter handy, see if you can measure any voltage between the NAVI unit ground (just touch the ground screw on the back or just touch a metal portion of the headunit and a known good chassis ground (almost anything metal in the car). If you measure any voltage (typically in the millivolt range), you have a ground loop.

If this all checks out OK - then you are left with a problem in the NAVI unit itself. Could be lucky and find it to be a blown fuse inside the unit (some are user replaceable, some are not). Could be the driver circuitry for the LED panel is faulty - broken solder, lifted pad, damaged wire, transistor(s) could be fired from a surge or other event.

Since you've already verified that the distortion is still present when you do not have the car running (just on ACC) - it is very likely that the problem is in the NAVI itself. Give the NAVI unit a good whiff, see if you can detect a very strong ozone/acrid burnt smell. Some ozone odor is normal, but it will should not be overpowering.

Try unplugging the FM antenna connection and see if that changes anything. Possibly be a short in the amplifier in the antenna. I'm assuming you also have the GPS antenna subcord for the NAVI unit. If possible, move that as far away from the NAVI as possible while testing. If you do not have the subcord, it could be possible that noise (RF interference) is getting to the unit in an unusual way and causing these interference issues.

[demens13]

Originally Posted by fishexpo101

Question: Does the distortion get any better/worse if you rev the gas pedal? Have you tried powering it straight from the battery?




If this all checks out OK - then you are left with a problem in the NAVI unit itself. Could be lucky and find it to be a blown fuse inside the unit (some are user replaceable, some are not). Could be the driver circuitry for the LED panel is faulty - broken solder, lifted pad, damaged wire, transistor(s) could be fired from a surge or other event.

Since you've already verified that the distortion is still present when you do not have the car running (just on ACC) - it is very likely that the problem is in the NAVI itself. Give the NAVI unit a good whiff, see if you can detect a very strong ozone/acrid burnt smell. Some ozone odor is normal, but it will should not be overpowering.

I will test for ground loops as you say. I've tried not hooking up the antenna as well but it made no difference. I'm starting to think its the head unit itself.

Not sure why i haven't tried just hooking up a battery to it to see if the distortion is still there earlier. Well, i hooked it up today in my garage away from the car, away from the antennas, away from everything and the distortion on the screen looks exactly like it was.

If you are familiar with the back of the unit, there are 2 plugs that go into, the bigger one has the power/ground/acc/speakers/antenna stuff and theres a smaller one. The big one i have figured out the wiring 100%. The small one not so much. The small one has some wires for CD Changer (which i dont have so they shouldn't matter) and it also has 2 other wires that the plug in the 2008 car does not have. From the Schematic i'm not exactly sure what those wires are for. 1 of them comes from the speedometer or cruise control (its hard to say exactly from the schematic). I did find this wire and connect it. It did not make any difference.

I found your question about rev interesting because the 2nd wire comes from there. I have not spotted it yet. But from the schematic it looks like it only makes a difference if the car is in Reverse. I have not tested it to see if there is any difference in the interference with the car in Reverse however.

With that said, considering that the unit does have the same interference issues with only 12v and ground connect to it would it be safe to assume that its a waste of time to look for the rev wire since its not likely to make a diff. As i've said early i THINK i'm narrowing down the problem to the unit.

1 thing that really bugs me is that it gets better with time. I've had a LCD computer monitor with a problem that got better with time. The culprit was a bad capacitor. But the problem was quite different other then the time thing. It was just a question of the monitor being dark for 30 min not getting enough power cause the cap was leaking (or something) but after a certain time to "warm up" the screen was perfect. Not the case here with this GPS unit. No issues with brightness, just the static.

I guess its time to take a look inside. As you say, maybe i can spot a bad component visual or by smell.

BTW, thanks for your posts. Its been very helpful. I've posted this question on other forums and noone has even replied.