So here is a weird one.
I plug my phone charger into my cigarette lighter socket. It's a generic USB charger. It lights up the green LED on the charger, but does not charge the phone. Plug the charger into my other car, it lights up the LED, and charges the phone just fine.
Fuse is fine in the charger and in the car for that circuit.
Is it possible that polarity is reversed on the cigarette lighter? Allowing the 12vdc to pass through the charger and light the LED, but however it reduces it to 5 vdc for the USB and maybe that circuit has a fail safe?
It's just sort of weird.
This is in a 2000 subaru 2.5rs. Only thing I can think of is that, I could have connected something wrong, when I had the faceplate off to mess with the radio, but usually that stuff is dummy proof(but maybe not in this case).
Which part of the cigarette lighter should get the +. I believe it should be the tip.
Check your alternator output.
I once had a charger do that, I discovered that my alt was on the way out and I was getting less that 12 volts to the cig lighter.
Alternator was freshly replaced this fall, with a reman one. I had weird electrical issues prior to that and that's why I replaced it.
I'll check to see I'm getting 12v.
What I don't get is that USB charging only needs 5v anyway.
If polarity were reversed the LED wouldn't light. Plus one on checking the voltage.
My 96 4 cylinder Ranger had a rough idle and would throw a check engine light. The codes said crankshaft position sensor bad. Replaced the sensor and still had the problem. I had replaced the alternator 6 months before. I took it back to NAPA and had them bench test it. Had a bad diode that was freaking the ECU out and throwing the code. Have the alt bench tested by a competent shop.
Make sure its not nasty inside. My friend had one do that and it was just full of car nasty and a little rust. Cleaned it up and it worked perfectly.
Have you tried plugging anything else into that socket? Or tried swapping fuses?
I've seen cracked fuses that will allow enough current to light up an LED but not enough for the circuit to be operational. So yeah, check your available voltage at the outlet. Better yet, put it under load with something (a taillight bulb is my favourite) and check the voltage while under operation.
If it isn't the fuse, there is likely some unwanted resistance elsewhere in the wiring.
Turns out the connection at the fuse was bad. Wiggling the fuse would get it to work. Eventually got the connection cleaned enough so it worked consistently.
