How to: Underdash lights that come on with headlights and dome light
#12
Not sure about putting the relay in the TIPM, you would have to find all the wires, connectors, etc, starts making it a lot more complicated.
If you use one constant 12v power source it starts getting pretty complicated. Your switch will be the last component before your lights. That way the switch has a direct connection to the lights. In your idea, you'd be using one relay for parking lights, another relay for the dome lights, with both of those run into a third relay to do the switching between them, and then the additional constant direct to the switch.
The only thing you are going to do by trying to do that is make it harder on yourself. I've done this on three trucks using the same wiring, hooking them up the same way, and there has not been issues I'm any of them.
Most leds have a current draw of about 20-25mA per led. At that current, it takes about 40-50 to pull ONE amp of current. You are not going to put enough strain on out to warrant all those relays. You are not going to need any diodes, unless you want to hook up two different power sources directly together. The spdt 5 pin relays will isolate the power sources and they will never be hooked together, since the relay closes and opens the two circuits opposite of each other.
Just wire it up as i explained originally, replace the switch with an SPDT on/off/on switch, wire the one side with the wire coming off pin 30 from the tertiary, and three other side with a 12v constant, such as from the battery, or power point. Our if you want to make sure your constant didn't stay on, to the accessory wires, such as the cigar lighter.
If you use one constant 12v power source it starts getting pretty complicated. Your switch will be the last component before your lights. That way the switch has a direct connection to the lights. In your idea, you'd be using one relay for parking lights, another relay for the dome lights, with both of those run into a third relay to do the switching between them, and then the additional constant direct to the switch.
The only thing you are going to do by trying to do that is make it harder on yourself. I've done this on three trucks using the same wiring, hooking them up the same way, and there has not been issues I'm any of them.
Most leds have a current draw of about 20-25mA per led. At that current, it takes about 40-50 to pull ONE amp of current. You are not going to put enough strain on out to warrant all those relays. You are not going to need any diodes, unless you want to hook up two different power sources directly together. The spdt 5 pin relays will isolate the power sources and they will never be hooked together, since the relay closes and opens the two circuits opposite of each other.
Just wire it up as i explained originally, replace the switch with an SPDT on/off/on switch, wire the one side with the wire coming off pin 30 from the tertiary, and three other side with a 12v constant, such as from the battery, or power point. Our if you want to make sure your constant didn't stay on, to the accessory wires, such as the cigar lighter.
#13
#14
Like i said, follow my directions, but when it comes to the switch, you'll add an additional 12v for master on power. I tired into the wire in the a pillar that gives power to the dome light circuit. I'm sure i could find a wiring diagram, but i know it's easy to get to, does what i need it to, and easy to get the wires into the dash. Why are you wanting to splice into the wires at the relays? Making it more complicated again. Use the wires you can access in the cab.
#15
I'd rather do the work at the relays for a few reasons:
1) keep all relays/fuses in the relay/fuse box where they belong.
2) In the end I'm going to add 2 or 3 new circuits and I don't think a bunch of relays and wiring will fit nicely into the little space on side of the dash panel.
3) I want the control line for the dome lights and not the dimming power line because I don't want this circuit to dim. just on/off.
4) I don't want the dimmer control for the parking/instrument lights to affect the circuit.
1) keep all relays/fuses in the relay/fuse box where they belong.
2) In the end I'm going to add 2 or 3 new circuits and I don't think a bunch of relays and wiring will fit nicely into the little space on side of the dash panel.
3) I want the control line for the dome lights and not the dimming power line because I don't want this circuit to dim. just on/off.
4) I don't want the dimmer control for the parking/instrument lights to affect the circuit.
Last edited by Sessrumnir; 02-19-2013 at 02:57 PM.
#16
I'd rather do the work at the relays for a few reasons:
1) keep all relays/fuses in the relay/fuse box where they belong.
2) In the end I'm going to add 2 or 3 new circuits and I don't think a bunch of relays and wiring will fit nicely into the little space on side of the dash panel.
3) I want the control line for the dome lights and not the dimming power line because I don't want this circuit to dim. just on/off.
4) I don't want the dimmer control for the parking/instrument lights to affect the circuit.
1) keep all relays/fuses in the relay/fuse box where they belong.
2) In the end I'm going to add 2 or 3 new circuits and I don't think a bunch of relays and wiring will fit nicely into the little space on side of the dash panel.
3) I want the control line for the dome lights and not the dimming power line because I don't want this circuit to dim. just on/off.
4) I don't want the dimmer control for the parking/instrument lights to affect the circuit.
1. I don't know about any extra spaces for relays in the TIPM. You'd have to figure out what pins are suppose to go to that relay, add the pins in, and then route your wires. I've seen where some other guys have done this in order to add in some stuff that was an option, but not installed on their truck.
2. Have you checked out that space? There may be enough space for you to at least do a couple.
3. The dome lights circuit in my installation does not dim. It does fade out with the overhead lights. When the headlight switch is off, the lights function exactly as the dome light.
4. If you don't want to dim the LED's with the instrument lights like I have mine set up, then split your wire from the parking light connection (in mine, the black 2 wire plug behind the center bezel), and run one to the coil, and to pin 87 on the relay. They will function independently of the instrument lights.
I went and bought a SPDT 3 position toggle switch (on/off/on), and wired it up today. I hooked up my lights to the middle prong, and wire from the relay to an outer prong. I ran a new wire from the power point (always on) and hooked it up to the last prong. Everything works as it should. One of the "on's", everything functions through the relay, and works like before. Switching it to off, of course, kills everything. And switching it to the other on, allows me to turn them on, on demand. Regardless of what else is on. My only problem was that I somehow blew the power point fuse when I was running the new wire, but after finding and replacing the fuse, everything works great, and I have no problems.
#18
No, I did not. The relay is a 30 amp relay, and all of the wires that I used already have stock fuses that are 20 amps or less. It's just as easy to me to replace a fuse under the hood, than it is to add a new fuse. Those fuses will blow before anything ever happens to that relay. Despite the fact that my total current draw with all of my lights is maybe 1 amp. I'll have to get out the DMM and check to see what the current draw is for all 5 LED strips in the next couple of days.
#20