fading ground and buzzing relay
Printed From: the12volt.com
Forum Name: Relays
Forum Discription: Relay Diagrams, SPDT Relays, SPST Relays, DPDT Relays, Latching Relays, etc.
URL: https://www.the12volt.com/installbay/forum_posts.asp?tid=94052
Printed Date: May 08, 2025 at 2:05 AM
Topic: fading ground and buzzing relay
Posted By: cberger62
Subject: fading ground and buzzing relay
Date Posted: May 18, 2007 at 9:41 PM
Here's the deal... I installed four cold cathode tubes in my truck. They work find but when the dome light starts to fade the relay buzzes and sounds horrible. Does anyone know how I can stop the relay from buzzing? Here is how the relay is wired.
Pin 30: fused positive constant (to battery)
Pin 85: ground signal from dome light
Pin 86: fused positive constant (to battery)
Pin 87: to red wire of cathode transformer.
Each transformer is grounded independently. Like I stated before, they work but the buzzing relay is killing the "cool" factor. Any help is appreciated.
Replies:
Posted By: cberger62
Date Posted: May 18, 2007 at 9:43 PM
Also, it's on a 2003 dodge ram.
Thanks again.
Posted By: hotwaterwizard
Date Posted: May 18, 2007 at 10:47 PM
It needs a different ground. You could hook your ground to one of the pin switches instead of to the fader. ------------- John DeRosa (Hotwaterwizard)
Stockton California
When in doubt, try it out !
Posted By: cberger62
Date Posted: May 18, 2007 at 10:57 PM
But the ground is what triggers the relay? If I gave it a constant ground the lights would always stay on.
Posted By: cberger62
Date Posted: May 18, 2007 at 11:45 PM
Scratch what I just said. I didn't see the second line of your post. Anyway, that would work but I would like to be able to turn all the lights on with the dome light, not just when the door is open. I do lots of work out of my vehicle and I installed the (white) cathodes for extra visibility. I don't want to have to open my door for them to come on. Any other ideas? Maybe a capacitor? But then as it discharges wouldn't it just do the same thing?
Posted By: hotwaterwizard
Date Posted: May 19, 2007 at 6:04 PM
I will work on it.
-------------
John DeRosa (Hotwaterwizard)
Stockton California
When in doubt, try it out !
Posted By: hotwaterwizard
Date Posted: May 19, 2007 at 6:12 PM
Have you tried this yet? Momentary to Constant Output
Once activated by the relay on the left, the relay's coil on the right will stay energized until either ground or 12v(+) is removed. You can do this with another relay. Or try connecting to a 12v(+) switched source instead of a constant one. Or you can have a door trigger activate a relay to break continuity. The variations are practically endless.
https://www.the12volt.com/relays/page5.asp#mtc ------------- John DeRosa (Hotwaterwizard)
Stockton California
When in doubt, try it out !
Posted By: hotwaterwizard
Date Posted: May 19, 2007 at 6:46 PM
 ------------- John DeRosa (Hotwaterwizard)
Stockton California
When in doubt, try it out !
Posted By: hotwaterwizard
Date Posted: May 19, 2007 at 6:48 PM
There must be a way to bypass the fader/Timer
-------------
John DeRosa (Hotwaterwizard)
Stockton California
When in doubt, try it out !
Posted By: cberger62
Date Posted: May 19, 2007 at 7:48 PM
I'll give the first one a try and see how it comes out. The other ideas I don't really like because they require the door to be open in order to turn the lights on. I want to be able to turn them on with the dome light switch too. Thanks for the help. If you or anyone else gets any ideas let me know.
Thanks.
Posted By: hotwaterwizard
Date Posted: May 19, 2007 at 11:07 PM
A manufactures wiring diagram would help here.
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John DeRosa (Hotwaterwizard)
Stockton California
When in doubt, try it out !
Posted By: cberger62
Date Posted: May 19, 2007 at 11:20 PM
Not sure what exact part you need but every wiring diagram for the truck is in here... '03 Ram Manual
Posted By: cberger62
Date Posted: May 19, 2007 at 11:22 PM
And thank you for your time 
Posted By: hotwaterwizard
Date Posted: May 19, 2007 at 11:34 PM
Sweet. You are a Genius
-------------
John DeRosa (Hotwaterwizard)
Stockton California
When in doubt, try it out !
Posted By: hotwaterwizard
Date Posted: May 20, 2007 at 12:12 AM
After reviewing the 85,144 kb and 2895 page PDF file. The best way to deal with this is to hook it into the Cargo lamp. ------------- John DeRosa (Hotwaterwizard)
Stockton California
When in doubt, try it out !
Posted By: cberger62
Date Posted: May 20, 2007 at 1:15 AM
Care to go a bit more into depth? Do you mean just use the cargo light switch to turn on the cathodes?
Posted By: hotwaterwizard
Date Posted: May 20, 2007 at 9:00 AM
Close use the cargo light switch to turn on the relay.
-------------
John DeRosa (Hotwaterwizard)
Stockton California
When in doubt, try it out !
Posted By: cberger62
Date Posted: May 20, 2007 at 12:23 PM
That still doesn't help me when the doors open 
Posted By: drvnbysound
Date Posted: May 20, 2007 at 4:53 PM
I run into a similar situation when doing a flip-down TV install in a 2004 Ford Escape. The dome light wiring in the Escape has constant 12V to the light, and the ground wire triggers the dome light to turn on when the doors are opened. This was the initital problem I had, which I figured I would use a relay to convert the (-) trigger into a +12V which the TV dome light circuit needed to activate. This was fine and worked when the doors were open and the dome light was on. But when you closed the doors the dome light would fade off, and would make the relay buzz (when turning on and off quickly) as I assume this was done with a PWM signal from the dome light circuit.
Personally I was unable to come up with a solution for this in the alloted time I had to do the install, so I just wired the light into a 12V source, and the switch on the TV allowed the light to be turned on and off manually, but was not able to wire it in to trigger with the dome light circuit.
If you come up with a solution, I would like to know for future installs of mine as well. Sorry for the long post; just wanted to share my experience as well.
Posted By: cberger62
Date Posted: May 20, 2007 at 6:19 PM
Here is what I think I'm going to do. I'm going hook the cathodes into my cargo light, like hotwaterwizard suggested. Then I'm going to find the wire from my alarm that turns on my parking lights when I disarm/remote start my truck and have it also turn on my cargo light. This way I can turn the lights on with the OEM cargo light switch and they will also come on when I disarm/remote start my truck.
Any opinions on that?
Posted By: cberger62
Date Posted: May 20, 2007 at 7:57 PM
hotwaterwizard - Where do you suggest I tap into the cargo light? At the light or at the switch? If you say switch then I need to find out what wire from the switch turns on the cargo light. Any suggestions?
Posted By: hotwaterwizard
Date Posted: May 20, 2007 at 8:59 PM
 ------------- John DeRosa (Hotwaterwizard)
Stockton California
When in doubt, try it out !
Posted By: cberger62
Date Posted: May 20, 2007 at 9:11 PM
hey man......you rock!
Thanks for your time.
Posted By: hotwaterwizard
Date Posted: May 20, 2007 at 9:16 PM
 ------------- John DeRosa (Hotwaterwizard)
Stockton California
When in doubt, try it out !
Posted By: cberger62
Date Posted: May 20, 2007 at 9:32 PM
Thanks again. Now I need to figure out how to make my cargo light come on with the interior lights when I disarm my alarm :-)
Posted By: hotwaterwizard
Date Posted: May 20, 2007 at 10:05 PM
LOL can't win. Hmmm lets see: Just hook the relay on a toggle switch and turn it on whenever you need it. ------------- John DeRosa (Hotwaterwizard)
Stockton California
When in doubt, try it out !
Posted By: Ween
Date Posted: May 20, 2007 at 10:28 PM
hi, from your first post on this subject: add a small diode (1N4001 or similar) in series with the lead from the domelight, banded side towards domelight wiring. next add a capacitor (2200uF or so, 16 volt or better) across the coil of the relay, negative lead to the same terminal that has the domelight lead. the diode will allow the voltage to operate the relay and also charge the capacitor. when the domelight fades away, the diode will only allow the capacitor to discharge via the relay, it should release with a simple click(no buzz). hope this helps mark
Posted By: cberger62
Date Posted: May 20, 2007 at 10:39 PM
Thanks Ween. I wish you would have chimed in earlier
At this point I've got my mind set on the cargo lamp. I think I'm going to go with the cargo lamp idea so that I can turn them on whenever I want without having to add an additional switch.
Thanks again for your help guys.
Posted By: cberger62
Date Posted: May 21, 2007 at 11:53 PM
I ended up hooking the cathodes to the cargo light switch. Works great. If I could get them to turn on with my alarm I'd be set. I'll post in the security section. Thanks again.
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