Electrical whine from brake lights - help!

[robstaco]

Okay non moded 2 month old 06 DC LB.

When I press the brake pedal there is a really high picthed whine that is coming from somewhere in the cab. This might be similar to the other post however I've narrowed it down to only when the brake lights are coming off and on. If I pulse the pedal the whining pulses with it. When I disconnected the blue harness brake light switch the whine is gone (but obviously the brake lights don't work either). I checked the fuse and third brake light bulbs for filament singing, (common in household dimmers when the filament in a bulb vibrates from different amp and current draw causing a high pitched whining sound or ringing) but that didn't do it.

This could be what other may be hearing unless your getting it regardless of the brake pedal being pushed. Happens with or without the key in the ignition.

Any ideas? Maybe a relay or loose connection?

Here's the thread that is very similar. Anybody have any results there as well? http://www.toyotanation.com/forum/t162334.html

[robstaco]

Stopped at the dealer and of course nobody there could hear it. Basic "36 month 36K mile warranty if it becomes a problem crap". I know I do not have super hearing and its coming from the dash area. Maybe if I have time over the weekend I'll yank some panels and see if I can trace it.

If any of you guys get a chance (not sure you want to open a can of worms on this one) but before you start your trucks with no outside noises preferably, press your brake pedal and see if you hear a high-pitched whine. It will be faint but definatley there. Once you let off it stops.....really strange.

[Thunder Fish]

Sounds like your ABS is coming on..............? just a thought

[robstaco]

Originally Posted by Thunder Fish

Sounds like your ABS is coming on..............? just a thought

Should it make a whinning sound? And whine everytime you tap, not stomp on the pedal?

[robstaco]

[Pb]

Sounds like a bad ground connection somewhere. Is the noize coming through the speakers? Pull the radio fuses and see if it still does it. That might help narrow it down.

[robstaco]

I hope its as simple as a ground. I will try and get into the lower dash today to see if I can hear it better. It seems to be coming from the driver side area. I'll pull the radio fuse like you suggested and see if it goes away.

FWIW the interior of this thing is very quiet IMO so it's much easier to hear all the little noises, but this one is driving me nuts. A constant whine is one thing, but one that only shows up with the brakes pressed is anoying as hell. I'll have to start stopping with the e-brake if I can't fix it.

[robstaco]

Okay I was able to locate the culprit. It sounds like a capacitor in the towing converter relay is making a high pitch whine when the brakes are applied. The relay in behind the fuse block inside the cab (drivers side) mounted to the left side way under the dash next to the firewall of the cab. It's a little black box with a wire harness going in the bottom. I removed the relay and put my ear to it with the brakes engaged and sure enough the high pitch whine is coming from there so I unplugged the box and left the cable hanging. All the lights are functioning so I'm assuming this box is only used when the trailer lights are plugged in. For now I'm not towing anything and the cab is back to quiet as a mouse.

I'm going to take it with me to the dealer tomorrow and see what we can work out. Since I basically found the problem on my own and can prove that to be the problem I wonder if they'll give me a replacement under warranty. I suppose if they want to horse around with it to say it's a manufacture defect or they won't cover I'd be okay with it. You can get to it without taking the lower dash apart once you know what you're looking for.

This MIGHT be what may be causing the high pitch whine others have heard. Takes about 3 minutes to try if you have not narrowed your problem down. Glad this solved it for me.

[robstaco]

Update! Stopped at the dealer and showed him the part and told the service guy what I did to find it. Low and behold a new one on order. Said hope this fixes it, no charge, be here tomorrow. Fingers crossed.

Worse case I leave the part out until I'm ready to tow something. They confirmed it's only used to regulate the brake lights on the trailer connection.

[06Sport]

nice find! i dont have the noise but a few here do. Would like to see if it is the same thing. Good job.