Possesed car cigarette lighter system

[parnelli]

I'm at my wits end on this one.

The car (volvo s40) has two outlets, one front, one back. The fuse in the fuse panel is functional- and I've even swapped it out just in case.

Here's the thing. Neither outlet fully works. The cell charger has an LED which lights up. The phone says it's charging- but it never charges.

Laptop won't charge, other phones won't charge, DVD player won't work....

So there's electricity there because the charger LED lights up. And the phone will show the little logo that it's charging- but obviously something is wrong....

ideas?

[cabinetman]

Probe it with a meter and see if they put out 12 volts.

.

[RAFlorida]

Check to see if you have the full

12 volts as CabinetMan post. It looks like you may have a bad connection somewhere. If you can, plug something into the outlet and check the voltage at the same time at that outlet. I suspect you'll see a drop in the voltage.

[parnelli]

Okay- Checked the outlet- with car running 14.2v.

Check the same outlet with cell phone charger plugged into the OTHER outlet and the voltage is 14.2 then 7.0, 7.9, 11 back to 14.2 cycling like that in about 3 seconds over and over.

Now that I'm thinking of it, the battery was replaced under warranty back in the fall. Related?

[parnelli]

Checked voltage in outlet A while different phone charger in outlet B and got same results. voltage goes to 7 then 9 then 11 then back to 14.

Voltage at battery does not change.

[Daryl]

Likely a bad ground. Check the pos. terminal of each outlet to a known good ground, ie the car frame.

[LinuxRandal]

Do your dash lights ever seem to flicker when your out at night?

If so, it would probably be the ground inside the car.

[cork58]

Could be the Body Control Module.

[LCHIEN]

if its under warranty take it back the Volvo dealer. Something definitely wrong.

[TB Roye]

Bad grounding on the two recpticals, make sure they are tight.

[gerti]

Probably hooked up to the blinker... ;-)

[parnelli]

if its under warranty take it back the Volvo dealer. Something definitely wrong.

Well- it *was* headed to the dealer in the morning for this, but I couldn't leave well enough alone and spent time avoiding other projects by tinkering with this today.

I've fixed the problem, but I can't say if I understand the problem.

Back last year a local store was going out of business and they had a package of assorted mini fuses that was only something like $2.00

But they weren't standard mini fuses- they have some sort of light that glows when the fuse has burnt out.

See here: http://www.amazon.com/gp/product/B0014458H6

and here: http://www.littelfuse.com/products/F...w+Pack+20.html

They're made by littlefuse, so it's not some weird one off thing.

Finally after taking the center console apart and checking grounds etc I say to myself "ya know- it's only this center console that has that new fangled fuse in it..." I pull the power window fuse out- put it in the cigarette outlet spot and.... the problem goes away! @##%%!

I flip them back- problem reappears. Try other of the light fuses all same thing.

So- I don't understand why this happens- I've seen these fuses at PepBoys, Autozone etc. --so they must be okay for someone-- but for some reason they just don't play nice with my car.

How a fuse with a little light in it causes the voltage to fluctuate like that is beyond me- but with a standard 'old fashioned' fuse in the fuse block everything works as it should.

[LCHIEN]

I'm going to hazard a Electrical Engineer's assessment of how these work.
Given that there's only two terminals to work with the glow part needs to be powered from the same terminals that the current flows thru.

My guess as to how this works then is that there's an LED and resistor in parallel with the fuse element - when the fuse element is intact the LED is basically shorted out by the fuse element and does not light. In this (normal) situation the fuse is in series with the load.

When the Fuse is blown or open then the LED and resistor allow a small amount of current to flow through the load, normally it would take about 5 milliamps to light an LED which is current limited by the LEDs resistor, and if the load is shorted then the load won't normally operate but will "leak" this 5 mA of current required to light the LED. 5 mA is but a tiny fraction of the normal current used by most automotive loads which are generally lights and motors and in the 5, 10, 15, 20 up to 100 Amp range.

If you have blow the fuse AND you have a complex electronic load then passing 5 mA may or may not make the load try to work. IN the case of an unloaded cell phone charger, the 5mA of current leaked to turn on the fuse LED will also be sufficient to turn on the charger LED. When you add the cell phone the current used is probably in the 50 or 100 mA range and will try to operate but operate erratically which accounts for the
fluctuating voltage you see as it alternately tries to run then probably shuts down for low voltage which allows the voltage to go back up and it restarts. With larger devices like the laptop, DVD etc it won't have enough current to work at all.

The net thing is that with a small low current load the load will actually seem to try to run due to the leaked LED fuse indicator current.

So my guess is that the fuse is blown and its leaking this small amount of LED current.
Try a heavier load (air compressor, emergency light, ) and the fuse will probably glow.
Replace the fuse with another glow fuse that's good, it'll probably work OK.
Test the bad fuse with an ohmmeter, if its not .1 ohm or lower, its fuse element is blown.