Dead Infotainment Unit

[ERover82]

Looked at the electrical side.

Fuses:
F64: 12v across terminals
F67 & F68: 0v across terminals
All fuses test good


Behind audio module
12v @ Blue/purple wire circled in green
0v @ red wires, circled in red


Behind touch screen
12v @ blue/purple wire, identified by yellow arrow
0v @ red wires on same connector

 

[discostew]

What happens with the system when it’s working correctly is the light is on steady when first unplugged. When it starts flashing is when it’s given up on coms.

 

[discostew]

What do you mean by 12V across the terminals of fuse 64? If you have 12 volts accross the terminals the fuse is blown and the other wire is still a really good ground. Looks like you should have 12v at the red wire that feeds both the screen and the audio head all the time.

 

[ERover82]

Thanks, definitely no red light at any point here.

I’ll double check those red wires.

12v at fuse box terminals, with fuse temporarily removed. I probably should have measured current instead.

 

[discostew]

Pretty sure the red wire you circled in red is a twisted pair going to a portable interface panel. like you plug your ipod into. I wouldn't bother with that one.

 

[discostew]

since your looking at that fuse you must have a schematic in front of you. So you see how both the screen and the audio head has its constant power from that. I bet your sneaking up on it now. 0 volts accross a fuse means that both sides of the fuse are at battery. No difference of potential. Thats a good reading as long as they both drive a test light.

Make sure your really on the correct fuse. The #s are above the fuse sometimes and below others. I always have to look pretty close to see the #s well enough.

 

[ERover82]

Just going off the decal behind the glovebox (see pic), but I'll probably need to find a diagram with the way things are going.

So constant power is F64, correct? I guess that's so they can remain in a low power state.

I should have done this before, but I got the Power Probe out. F67 & F68 both read 0.1v on one terminal and 0v on the other.

I considered supplying power to either terminal to see if a device powered up, but didn't want to fry anything. I'm guessing the 0v terminal would be the correct one to supply power to for testing. Maybe the 0.1v terminals lead to bad 12v+ wiring?

 

[ERover82]

Today I found that supplying power to either F67 or F68 resulted in the touchscreen powering up, but not moving beyond displaying the logo.

 

[ERover82]

It works! That new audio module arrived, I plugged it in, and it fired right up. All functions work even though the module is newer and has a slightly different part number. Peering through the case, I did notice this unit also has more solid capacitors in place of where electrolytic capacitors were in the old one. Power to the touchscreen, etc, must be triggered by the audio module which is why I didn't see any voltage on F67 and F68. Thanks for the help Stew.

 

[Blue]

Nice! Maybe I’ll try another audio module.

 

[ERover82]

Nice! Maybe I’ll try another audio module.

Through this process I discovered there's an audio relay on the main fuse block that powers the touchscreen, etc. You might try swapping it with the cigarette lighter relay, just in case it's going bad.

 

[Blue]

I need to dedicate a couple hours to working on this issue. Need to pull apart the dash again and check the MOST ring connections like Stew has advised. My touchscreen and all other components have power, it's just the intermittent cutting out that is the issue. The touchscreen works fine, in about 5 to 7 second increments....makes setting the time and date interesting, have to be fast.

 

[ERover82]

Follow up. Son and I dissected the audio module and found corrosion. Obviously some moisture from sitting much of the winter got in there.