Cigarette Lighter Isn't Working (But Gets Power)

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Sep 1, 2015
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I'm trying to figure out a weird problem with my 1978 FJ40's cigarette lighter. Electronics are definitely not my strong suit.

My brother (@BRShap) and I bought our first 40 last week, and I'll post a thread about our road trip bringing it back to NY from Alabama soon. Truck is in great shape, but we can't get the cig lighter to work, and it won't work with a USB charging adapter.

Our first though was a blow fuse, so we used a multimeter to test the fuse and it isn't blown. Next we looked under the dash and pulled out the ashtray for better access, and found that the red wire with a black stripe and bullet connector was loose. The other white wire was attached. We figured that was the problem and connect the bullet, but lighter still did not work.

I then used the multimeter to test the outlet, and MM detected some voltage, so I know there's power going to the outlet. This has me pretty stumped. If current is flowing, why isn't the lighter or USB charger working.

All I can think now is that the whole unit is somehow damaged and needs to be replaced. I don't see any signs of rust or dirt, but haven't pulled it all out yet.

Do you guys have any idea of what's going on? I've searched the forum, but haven't found the same problem.
 
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In my '40, the ligher socket itself has some corrosion in it, so that I have to fiddle with what ever I plug in to that socket to get it to power up. After disconnecting the battery, I figure some WD40, steel wool and some elbow grease would take care of that.
 

honk

 
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I use a 12 gauge shotgun bore brush soaked up with contact leaner and driven by my drill to max those sockets up cleaned, and that's usually enough.
Should be a nice 12v at the socket center - if there's something less then it's time to chase the grounding because somewhere between the socket and ground point is more resistance than design. (resistance up = voltage down, current remaining unchanged)
 
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Is it rusted at all? You should be getting around 12V on the terminals for it. On my '70 FJ40 it is grounded to the dash and has one terminal that connects to the rear. Mine was completely rusted out and I bought a new one, easy swap.

I use a 12 gauge shotgun bore brush soaked up with contact leaner and driven by my drill to max those sockets up cleaned, and that's usually enough.
Should be a nice 12v at the socket center - if there's something less then it's time to chase the grounding because somewhere between the socket and ground point is more resistance than design. (resistance up = voltage down, current remaining unchanged)
Not going to lie... done that before! Battery Post/Terminal cleaners work as well:
 
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Thanks for the responses guys.

Its really not rusty at all inside so I tend to think thats not the problem. Ill break out the multimeter and check how much current is coming through tomorrow.

Im not sure where its grounded to. theres a white wire with black stripe that plugs into the bottom of the lighter but I cant see where it goes.
 
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Thanks for the responses guys.

Its really not rusty at all inside so I tend to think thats not the problem. Ill break out the multimeter and check how much current is coming through tomorrow.

Im not sure where its grounded to. theres a white wire with black stripe that plugs into the bottom of the lighter but I cant see where it goes.
The ground is going through the metal dashboard it's on. Put the negative (black) lead of your multimeter, preferably on an unpainted surface, of the dash or another ground (body of cig lighter would do) and positive (red) lead on that wire and it should read around 12V. Your looking for voltage, not current.

Sent from my Nexus 4
 
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The connections in both the wires that plug into the socket as well as the fuse on the 12v supply side have to be very solid for the lighter to work - it takes a fair bit of amps to heat up an element . Any corrosion , burnt contacts and such will show good on a meter but the lighter element will not get enough current to heat up . I just replaced mine this last summer since it was corroded enough to make it sporadic and unreliable - yes , I actually use it and still smoke . I think a new one was around $30 - identical to the original other than not being corroded and dirty - Beno is your friend on these parts .

Sarge
 

Coolerman

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The ground is going through the metal dashboard it's on.
Not on a 78, the White/Black wire that attaches to the lighter is the ground connection.
dshap, you said you had voltage on the center connection? How much? Should be battery level ie 12.7 to 13.2 volts on a good battery.

Next thing I would do: Set your multi-meter to OHMS. Black lead to a GOOD body ground like a bolt head, red lead to the unplugged White/Black wire. It should read LESS than 2 ohms. If it does, you have a good ground wire. Now clean the male tab the ground wire attaches to and put it back on.

You may have a bad lighter element or one that will not work in the FJ40 socket.

You may have a USB charger that has a power port plug, NOT a lighter plug. They are two different things. Try to find an OLD device with a 12 volt plug on it and try that. If that works then you can play with the USB plug (bend the ground things out a bit to make better contact).

Personally I would install a true modern power port socket where the old lighter plug is ,OR add this under the dash.
 
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I did exactly that on mine - just added a power port under the dash since most lighter sockets are not compatible with modern power port plugs . My 03/'77 has a separate ground wire as well .
Sarge
 
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Not sure if this helps, but I have a 78 and mine did the same thing and I cleaned the corrosion out and now the lighter and USB chargers work fine. I also had to replace the fuses too which kept giving me intermittent problems.
 

ErikinSC

..and then he said.. 'Hey y'all! Watch this'
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The original cigarette lighter is not a 12V accessory port - as mentioned above. The side tabs create a short when a device is inserted. Replace the socket with a 12V accessory port, or the neat trick @Trollhole pointed out. Problem solved.
 
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Had the same problem. Measured 12v and cigarette lighter and connections looked fine. Turned out I had corrision at fuse block. Voltage was getting through, built little current. Brushed naval jelly, let it sit, then spayed it of with contact cleaner. After that had full current and a lot of other things started to work better. Did that to entire fuse block. Back looks like new.
 
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Just wanted to update this thread with the conclusion....

First off, thanks for the advice guys.

Unfortunately I'm not exactly sure what the problem was, because we got a little confused and did too many things at once. Bottom line is that we replaced the fuse and lightly sanded the cigarette lighter connections, and it works! I changed the fuse before, so I don't think that was the problem, but not totally sure. At least it works now.
 
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The old glass fuses would sometimes build an oxide layer on the metal ends - it's almost invisible and unless you have a direct amp meter connected in series you'd never see a current drop , it's common on older cars . Best to use a good stiff brass bore brush with the battery disconnected - clean all those fuse holders and replace with new fuses , not old ones that have been laying around . I coat mine with a very slight wipe of dielectric grease as well - stops all the issues with oxidation .

Sarge
 
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most lighter sockets are not compatible with modern power port plugs
The original cigarette lighter is not a 12V accessory port - as mentioned above. The side tabs create a short when a device is inserted.
I just don't get this.

1st, I don't understand what you're talking about. Can you explain with a diagram or a web reference?

2nd, every cigarette lighter port in all my four vehicles ('76, '78, '93, '02) work just fine with the 3 or 4 accessories that I've tried in them, as well as the original cigarette lighters, including the two original fj40 cigarette lighters, multiple usb 5v adapters, 110v inverters and my roll-bar rack with led lights plugs in there too.
 

ErikinSC

..and then he said.. 'Hey y'all! Watch this'
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@Fast Eddy - the old lighter sockets had a U-shaped positive strap tat made contact on the center tip and the sides, of a cigarette lighter, to hold the element "in" while heating up the element. See the little tabs sticking in and connected across the center?

image.jpeg


Maybe not on Mr Toyota's truck... But on the one's I've had problems with. The lighter has to be pushed 'IN' to contact the 12V and heat the element.

image.jpeg



When you insert a modern device, if the side (ground) springs contact the frame (ground) and the hot lead at the same time - > short, blow a fuse.

image.jpeg


The negative spring ^^ above, could cause a short between the hot 12v connection and the
U shaped center lead' with outside chassis.... Does that help?

I am not a smoker... Just had to learn how the damn thing worked b/c it DIDN'T WORK..in my truck.
 
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That is correct , and I've seen modern power adapters short out old style cigar lighter ports and blow a fuse . It all boils down to the distance of the plug between the 12v+ tip and the ground contacts on the side of the plug - if they are close to the end they will short out . Seems low-quality plugs are usually the culprit , decent plugs have better material spring steel contacts that are farther up on the body and won't hit that u-shaped contact plate . I watched a poor soul nearly burn down a '48 Ford custom pickup at a cruise night in the parking lot when his wife plugged in her phone with an aftermarket spare charger cable to charge the battery - and the idiot that wired the truck for him had no fuse on the cig lighter circuit . We got the hood open and I chopped off the fuse link wire with with a multi-tool to stop the fire . Had to do some temp repairs to get him home as most of the dash wiring got burnt up , but we got him home. Wish I had pics of that night - the amount of smoke was incredible coming out of the cab - never did hear what it cost him to repair the truck's interior and dash .
Sarge
 
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