New HU install, interference from brake lights and turn signals.

[Andy Somnifac 10+ year member]

Hey everyone,

I have recently installed an Eclipse AVN2210P Mk II in my 2000 Toyota MR2 Spyder. So far I love the unit. I only have big issue at the moment, and it's not even that big of an issue. I get interference when stepping on the brake pedal or using turn signals.

The setup is as follows:

* AVN2210P MkII HU

* MTX Blue Thunder PRO4X75 Amp

* Infinity Reference 6022i 6 1/2" Speakers in the doors

* Rockford Fosgate Punch P1694C 6x9" Speakers in the rear

I've done the following to try and trace the source:

* Checked to see if the interference is noticeable when running off the HU's amp. It is not.

* Plugged an iPod into the amp's input to see if the noise is noticeable. It is not.

And a rundown of other items that may or may not be relevant:

* I've taken the ground off the vehicle's harness and firmly grounded it closer to the HU.

* The ground on the amp is approximately 12" long, and grounded right below where the amp is mounted in the rear cubby.

* The signal leads between the HU and the amp are beefy RCAs, run under the door sill on the right side of the car.

* The level of the interference decreases as I turn down the gain on the amp. I can get it to the point it's barely noticeable, but I'd like to eliminate it so I can turn the gain back up a little bit.

* The interference sounds like a quick pop when I depress the brake pedal, and the same when I release it.

It has been suggested that I take the power lead to the HU and run it straight back to the battery, because a couple theorize it could be some kind of voltage drop that's causing the interference. Anyone have any thoughts on this theory, or any other thoughts and suggestions as to things to check?

Thanks.

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[mdillon 10+ year member]

your power wire for your HU may be spliced off of the power from the lights. i would run a new wire for the HU and possibly upgrade the grounds to your lights.

 

[kovemaster559 5,000+ posts]

i think voltage drop y dont u run all the cables,make new harness thats what i would do that way u dont starve the unit its like ur amp would u hook it to the fuse box i doughtt it so yeah i say make new harness shouldnt be that hard. plus alot easier i think

 

[Andy Somnifac 10+ year member]

Thanks guys. I'll run a fused line straight to the battery. 14 gauge wire be proper in your opinions?

 

[Zakerid 10+ year member]

14 would prob. be fine but I would use 12

 

[ARSkemp 10+ year member]

I had the same problem when running the accessory power to too many things at once (2 amp remote wires and an equalizer remote wire). It was w/ the same head unit, it made the pop sound only when I put the left turn signal on.

I solved the problem by using a relay for the remote turn on wires.

This was also at the same time i put a new power/ground wire for the amps so that may have been it too...

 

[Andy Somnifac 10+ year member]

ARSkemp,

Just to make sure I am following what you're saying, did you add a relay, run from some other 12v switched source, and a lead from the battery to the relay, and to your accessories (amps, equalizer)? Or did you run it to your HU? I'd imagine this would further isolate the HU against voltage fluctuations, if I'm visualizing this properly, and was curious if you think doing this with the HU would be worthwhile.

Please excuse my low level know knowledge when it comes to car audio and electronics. I know enough to install a HU and amp, and enough to be dangerous, but I want to make sure I understand what you mean.

Thanks.

 

[ARSkemp 10+ year member]

I ran the relay for my accessories (amps, eq, etc).

I'm not sure if doing this with the HU would be worthwhile or not, since i don't think i know much more than you (ive done maybe 3-4 system installs). Their may be others here that will be able to chime in about that though. I just remember others suggesting to add a relay for over 2 amps, and i decided to install one since i was rewiring things anyways. I wasn't installing it to fix the problem, i was just doing it since it was recommended and something i did when rewiring just happened to fix that problem in the process.

 

[Andy Somnifac 10+ year member]

Thanks for the input.

I guess my plan of attack will to first wire the 12v constant for the HU directly to the battery. If that doesn't solve the issue, I'll run a line between the battery and the 12v keyed, using a relay and some other 12v keyed source to trigger the relay (maybe even the 12v keyed on the radio harness?). The second will be last resort though.

If anyone else has anything else they think might help add to my understanding of the problem, please, I'm all ears.

 

[Andy Somnifac 10+ year member]

Well, I just ran a dedicated line between the battery and the HU's 12v constant. Unfortunately there was no change... I guess the next option is to run another line from the battery to the 12v keyed, via a relay.

And maybe I'll have to poke around at my grounds again, even though they seem to be OK.

 

[Andy Somnifac 10+ year member]

Just messing around during a little breather from work, I pulled on of the tail lights from the car. The interference from the turn signal disappears completely, and the interference from the brakes lessens. It of course completely disappears when I remove the other tail light. So, it seems that when the the tail lights and brake lights are @ their full draw, the interference is at its worst.

Looking at the cable run for the tail light harness, it seems that it runs through the firewall, down the length of the car and looks like it grounds in the passenger foot well. I can't be certain if that's the case, as I was only poking around on a 15 minute break.

Based on that information, it spark any new ideas?

I plan on switching out the bulbs in my tail lights to LEDs. I wonder if they will make a difference, since their draw is so much less when compared to a incandescent bulb. (just wondering aloud)

 

[Andy Somnifac 10+ year member]

Didn't get a chance to mess with the system this weekend, but have been thinking about it. I read that running the ground straight to the neg post of the battery. I'll run the amp's ground to the neg post too if nothing comes of this.

Anyone have any thoughts on this?

 

[Andy Somnifac 10+ year member]

Well, ran a ground from the HU and the amp to the neg battery terminal. No change... Any other ideas?

 

[Andy Somnifac 10+ year member]

Well, even though no one seems too interested, I rerouted the RCAs between the HU and the amp and it lessened the issue to the point that I can live with it. The actual pedal assembly is louder than the click. To run the RCAs an other way would require me to disassemble most of the car's interior, which I don't currently have the time, or desire, to do.

But the bad news... Whatever I did has now induced an alternator whine into the system... I recently (last week) installed a set of fog lights on the car, and this seems to be tied to them. It's worse when the fogs are on. The power line does run somewhat near the RCAs for about 1.5' - 2' at the front of the passenger compartment. Looks like I'll have to find a high current source in the front compartment of my car that can handle the draw (mid engine car, so it's not as simple as going to the battery), and relocate the relay up there.