tow truck lightbar
Printed From: the12volt.com
Forum Name: Lights, Neon, LEDs, HIDs
Forum Discription: Under Car Lighting, Strobe Lights, Fog Lights, Headlights, HIDs, DRL, Tail Lights, Brake Lights, Dashboard Lights, WigWag, etc.
URL: https://www.the12volt.com/installbay/forum_posts.asp?tid=105895
Printed Date: July 12, 2025 at 4:32 AM
Topic: tow truck lightbar
Posted By: whitextreme
Subject: tow truck lightbar
Date Posted: July 03, 2008 at 10:13 AM
I am working on a tow truck that currently has a Federal Signal Lightbar installed on it. It has 4 rotators in it with 55W bulbs in it. They said the switch got hot and stopped working when they had the beacons on. I am assuming that this should be ran through a relay and not just through the switch right? I have not looked at it yet I was just trying to get some information because I dig in.
Replies:
Posted By: i am an idiot
Date Posted: July 04, 2008 at 9:59 PM
Yes it sounds like you need a relay. A standard Bosch/Now Tyco relay will handle 30 amps of current.
Posted By: whitextreme
Date Posted: August 03, 2008 at 12:38 PM
I know that it has been a while, but I finally got a chance to look at this truck and this is what I found. The main power and ground wires are 10g. The power wire has a 25a fuse in it. All of the rest of the wires are 12g and the is another 25 amp fuse going to the relay. Also the switches themselves are rated to handle 20a. There were a couple damaged connectors in there and the switch was bad so I replaced all of that. It seems like everything is working correctly now I just wanted to make sure this seemed like a proper wiring setup. Also the lightbar says it should draw 17.2 amps and the alley lights should draw 12 amps. I am not sure about the other 2 sets off work lights they are not marked. 
Posted By: reax222
Date Posted: August 25, 2008 at 4:28 AM
On my old federals, the motors and lights are on separate wires. You may want to see how much current the motors are pulling. I've know and seen older bar's motors short out, in fact I think that is why I have the two at home that I do.
Posted By: whitextreme
Date Posted: August 25, 2008 at 12:12 PM
The wiring on the lightbar is from the factory and is only has 1 12 gauge wire running the lights and the motors for the rotators. Since I posted that I did check the amperage draw on the wire and it was only 16 amps.
Posted By: reax222
Date Posted: August 26, 2008 at 2:09 AM
I pulled mine out, it's a southern VP, but they are all close enough. It does use one large hot and one large ground, with another 4 pairs of wires. The alley lights should not come one with the takedown lights. Some bars also have flashers.
A good switch should handle takedowns alone, then the alley lights are typically switched for each side. It wouldn't hurt anything to run a relay to protect the switch, but it shouldn't be needed. I think that says wheel lift lights. They too should be on their own switch (some states have light laws that lights that high can't be run on the street let alone facing backwards while driving.)
So your switches should be, warning lights (takedown), R alley, L alley, flood.
Posted By: whitextreme
Date Posted: August 26, 2008 at 9:19 AM
Excellent thank you for the info. I wanted to run a relay just to be safe because the switches they got don't look like the best quality and the are not marked with any amperage. They I will have to break up the 2 alley lights and run another wire. Also I know about not running the bed and wheel lift lights when the trucks are moving it just makes it a lot easier to get hooked up with light in both places. Thanks again.
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