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Discussion Starter · #1 ·
I'm trying to diagnose an issue I'm having with my 2013 Passat TDI SEL with the RNS-510 head unit. All of a sudden last week, I lost all sound to the speakers. No radio, no Bluetooth phone, no NAV sounds, chimes, etc...

I've tried various things, including a reset of the head unit (holding down the 3 buttons on top), disconnecting the battery for a few hours, etc...

I'm thinking the issue is that the amplifier has failed, or the fuse protecting the amp has blown. The problem is, all of the diagrams I've found online for my model don't look like the fuse box under the hood) where the fuse for an amp would be located).

I've disconnected the amp itself to tried to test for power with a multimeter at the wiring harness it attaches to, but the holes on it are too small for my leads to get in there and I'm not sure which of the dozens of holes on the adapter I'd need to test anyway since most are speaker wires, not the power from the battery. I've tests the fuses (with a multimeter) in the engine compartment and side of the dashboard just to be thorough, even though they're not for the amp, I simply can't find why I'm not getting sound.

Attached are pics of my fuse box under the hood, a diagram I found online of what a B7's fuse box should look like, my factory amp, and (installed), and the front and back of my amp removed.
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Thoughts?
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Use paperclips to probe the terminals with. For power, you are looking for the largest gauge wire. One of the 2 larger wires should be brown, which is ground. If the fuse is in the engine bay fuse box, there are only (3) 30a fuses. If it's really pos.19 in the box according to your screen cap, I would guess it's the 30a ATC fuse in the lower right corner of the pic. Counting 19 spots of the smaller fuses starting with the upper left fuse first.
 

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Discussion Starter · #3 ·
Use paperclips to probe the terminals with. For power, you are looking for the largest gauge wire. One of the 2 larger wires should be brown, which is ground. If the fuse is in the engine bay fuse box, there are only (3) 30a fuses. If it's really pos.19 in the box according to your screen cap, I would guess it's the 30a ATC fuse in the lower right corner of the pic. Counting 19 spots of the smaller fuses starting with the upper left fuse first.
I tested all of the fuses under the hood for continuity and they were good, including the dark green 30a on the lower right in my pic.

The fuse box diagrams that I see online however look nothing like what's under my hood.

I'll try some paperclips in the harness that connects to the amplifier, but it's tough to tell what any of the holes in that adapter even lead to (no way to see the corresponding wires, color or sizes).
 

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Larger wire requires larger terminals. Look at the amp and narrow down from there.

The two I circled are likely power and ground


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Discussion Starter · #5 ·
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Larger wire requires larger terminals. Look at the amp and narrow down from there.

The two I circled are likely power and ground


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Makes sense, this is what the harness looks like, and I can try both of the larger terminals (which I circled too), but where would the black probe go when testing for DC voltage to the amplifier?
 

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Black probe to the other large terminal or a ground point on the car. A stud with a nut and brown wire on it.


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Discussion Starter · #7 ·
Black probe to the other large terminal or a ground point on the car. A stud with a nut and brown wire on it.


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Thank you.

Just tested the amplifier adapter and used the 2nd port on the right that I had circled. I put a 2nd wire lead into one of the two holes above it and my multimeter showed DC voltage!

Based on that, I think I can assume that the amplifier just decided to randomly die on me and that the fuse/wiring is all intact?

Now I'll need to decide if I want to buy a used amplifier from another B7 Passat or go aftermarket with it.
 

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Looks like used OEM amps go for the $2-300 range. Myself, I would decide between that and doing a whole system changeout at roughly $1000 - sky.


 

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I wouldn't be so sure it was the amp. What you probed was the main power wire. There also needs to be a control wire(s) (CAN) that turns the amp on. If the amp does not know to turn on, then well...there you go. You'll need a scanner capable of scanning the different modules in the vehicle to see if there is a break in the communications somewhere.
 

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Discussion Starter · #12 ·
That doesn't explain why the used amplifier that I purchased off of eBay worked instantly when I plugged it in and the sound from my speakers returned.

The system worked flawlessly again for 2 weeks, until suddenly dying this weekend. I did have a dead battery this morning due to cold weather and recent short trips, but plugged it into a charger and it's fine again... I don't think losing power for a few days would have any relation to the no sound from speakers issue?
 

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Discussion Starter · #13 · (Edited)
Bumping my old thread... been driving around with no sound for a year and a half... got around to taking it into the dealership and they recommended a new amp. I found a used amp that was tested and works but plugged it in and still no sound. I do here a faint "pop" in the speakers when the system starts up, a sign of life that wasnt there previously. Perhaps it's a short to a speaker?
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