Cigar lighter - Hot at all times, can that be changed?

[jballard81]

According to the EVTM the cigar lighter is hot at all times. I am more accustomed to that being keyed power (accy or on)

I'm sure one day (when my transmission is put back together ), I'm going to forget to unplug my phone charger and it will eventually drain the battery...

Again, least of my problems right now but I'm still waiting for transmission parts to show up.

Would the 'correct fix' be to run a new wire to a keyed source? That seems easiest, but doesn't account for what the existing load could be on that circuit.

Would also be nice to be able to run my 100watt laptop charger if I ever needed to. I feel like that would best be served with a new circuit that could potentially take advantage of one of the empty fuse locations in the engine fuse box.

Then again, the way the manual reads, it looks like all the fuses on the engine bay should be considered hot all the time. Which would not in fact help me here..

Anyone else mess with this before and have a safe solution?

 

[RonD]

Yes, people have just put a 12v 30amp relay on that wire, key on activates relay, still have the full amps available

Cigar lighter fuse also powers OBD2 port in 1995 and up

There is a Ground at cigar lighter so a ground for the relay, and the 12volt wire which you just cut to hook to relay's in and out wires
So just need 1 wire to Key On source, could use Radio's power on wire

A relay can handle the 20-30 amps of one circuit passing thru it, like cigar lighter
But to activate it only takes 1/2 amp, 0.5amp, so a relay can be added to ANY circuit to control it and not effect that circuit

It could even be used as a cigar lighter after relay is installed
And ALL the fuses stay the same, cigar light fuse is still the cigar lighter fuse, Owners manual matches up, nothing to remember, lol

 

[RobbieD]

If you're just planning on light loads (like device charging), and you're not going to use the cigar lighter at all, you could splice off the radio power wire (Yellow/Black) with a short length of wire to power the lighter socket. You can use a female bullet connector to plug into the lighter stud, and just tape off your original Yellow/Ly Blue wire's constant connector.

If you want the lighter socket capable of large loads, a simple relay triggered by radio power wire and powered by the original lighter wire will restore the original capability, but as a switched not constant.

The radio power circuit would work the best, as that would give you power with the ignition key "on" or in "accessory" positions.

 

[bhgl]

A relay is the way to go, I had the same feeling about the power port on my truck, and didn't want to constantly yank on my USB charger every time I got out of the truck, but didn't feel like bothering with a relay.

So I wired in a toggle switch to turn it on and off, super simple, I basically took the power wire for the power port (not cigar lighter) and wired the toggle in between, doesn't really stop me from forgetting to turn it off, but it really comes in handy because I simply forget to turn it on.

 

[jballard81]

Yes, people have just put a 12v 30amp relay on that wire, key on activates relay, still have the full amps available

Cigar lighter fuse also powers OBD2 port in 1995 and up

There is a Ground at cigar lighter so a ground for the relay, and the 12volt wire which you just cut to hook to relay's in and out wires
So just need 1 wire to Key On source, could use Radio's power on wire

A relay can handle the 20-30 amps of one circuit passing thru it, like cigar lighter
But to activate it only takes 1/2 amp, 0.5amp, so a relay can be added to ANY circuit to control it and not effect that circuit

It could even be used as a cigar lighter after relay is installed
And ALL the fuses stay the same, cigar light fuse is still the cigar lighter fuse, Owners manual matches up, nothing to remember, lol

I like this concept. Just to make sure I understand though.

-12v relay with power coming from the existing 20 amp power line currently in place for the cigar lighter
-relay trigger jumper into the radio power since it's keyed and close by
-profit!

Seems like the best course of action bc I would want to be able to remove my 3D printed panel and replace the OG ashtray.

 

[RobbieD]

Yes, your understanding is correct.

It's actually a pretty simple, straightforward modification.

 

[jballard81]

Yes, your understanding is correct.

It's actually a pretty simple, straightforward modification.

does it matter if i use a 'positive' trigger type relay and connect it to radio power
OR if i use a 'ground' trigger type relay and connect it to the radio ground?

 

[RobbieD]

You just need a "standard" Bosch-style universal relay. The cheaper 4-pin version is perfect for what you're doing.

It will be positive triggered from tapping into the radio power wire.

The pins are numbered: 85, 86, 30, 87, and 87a if it's a 5-pin.

Splice a wire from the radio power; it goes to pin 86.

Ground pin 85, by splicing a wire from the cigar lighter socket ground wire.

Cut the cigar lighter's power wire. The 2 cut ends go to pins 87 and 30.

When I wire a 5-pin relay as simple switch device without a socket, I put power in to 87, and power out to 30. On a 5-pin relay, 87a and 30 are connected when the relay is "off" (NC, normally closed). This way you don't have the hot terminal in the center when relay is off, that should be covered (if you're not using a socket).

Otherwise, on a simple switch application pins 30 and 87 are interchangeble. The general standard is 30 load in and 87 load out, and that should be used if you have a socket with the relay, which insulates the unused pin 87a..

 

[RonD]

Radio is always grounded, so no can't use that as a ground trigger

 

[Blmpkn]

I wouldn't worry about a phone charger flattening the battery.. I left a Bluetooth transmitter plugged in on my 2010 the entire time I had it with no issues. The screen on that thing definitely used more juice than the single led bulb that most phone chargers seem to have too..

 

[CamTheHedgehog]

Cigar lighter fuse also powers OBD2 port in 1995 and up

I didn't know this until recently, when testing a small 12v pump which was seized and it blew the fuse. Of course, as it was seized, I had no way of telling that I had blown the fuse.

Then my app for my always-plugged-in bluetooth OBDII reader started yelling at me, as it hadn't been able to talk to the unit in quite some time. After much head scratching, multimeter probing, and finally a google search, I found out about this wonderful idea from Ford to put them on the same fuse.