Blown radio after air compressor on cig lighter

[Cody2289]

I bought a Vanagon a few days ago and the day before I bought it, the owner used an air compressor powered from the cigarette lighter to inflate the tires. That clearly caused a meltdown of something and it blew 40amp fuses as soon as previous owner placed them. (I know he should not have been placing 40amp fuses there)

I disconnected the cig lighter and 15 amp fuses are now surviving, the map light and interior light turns on, but the radio is still dead. I changed the 10 amp fuse inside the radio, no change.

I used a test light just now to see that the cigarette lighters wiring still seems to be working so I’m assuming there’s no damage to the wiring - just the cig lighter itself melted down somewhere.

So what do you think is up with the radio? Could it just be dead dead? Sucks to be chasing things on day 1 of ownership but I guess this is welcome to the club! “Help!!!” Thanks in advance

I like tinkering but even in college physics I didn’t wrap my head around amps and ohms and whatnot. I’ll see if the radios power wire is getting power now

Update: I could not get a power reading on the radios fuse or harness. I tapped the multimeter on the old cigarette harness and it instantly blew the fuse again. So basically that means there is a melted wire somewhere?

[djkeev]

Do you have a test light or multimeter?

Pull the fuse at the radio and check fir power there.

If you have power, try another fuse. Still no good? Your radio has troubles.

No power at the fuse? Start tracing backwards until you locate the problem.
If it isn't the VW radio, the "professional installers" often aren't so professional and the connections are crap.
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Ghia
http://www.thesamba.com/vw/forum/viewtopic.php?t=392473

Vanagon
http://www.thesamba.com/vw/forum/viewtopic.php?p=6315537#6315537

Beetle
https://www.thesamba.com/vw/forum/viewtopic.php?t=482968&highlight=74+super+vert

[MarkWard]

Modern radios have 2 power supplies from different locations. One is power all the time for memory and clock if fitted. The other power is for the radio to operate. You need to check for both.

My portable compressor has large wire clamps and goes directly on the battery terminals. As you can see, lighter sockets aren’t really suited for big loads.

[Cody2289]

I have a multimeter and a test light. I’ll get to looking at it now. I honestly just want the radio to be toast and move on. It is an aftermarket radio, looks like they knew what they were doing but it’s always a rat nest. Also have a green switch on the cluster that makes a beep when I switch it…. Wonder what that does

[Cody2289]

I could not get a power reading on the radios fuse or harness. I tapped the multimeter on the old cigarette harness and it instantly blew the fuse again. So basically that means there is a melted wire somewhere?

If it makes any difference, it’s blowing the fuse with the power off. So that cigarette lighter is getting constant power. Not sure if that’s normal in these vans or not

[MarkWard]

Yes the lighter socket is wired constant power. Not sure how testing it with a meter is blowing the fuse. If the circuit was shorted, it would blow immediately when you installed a new fuse. If you touch the bottom center of the socket and the side of the socket with your probe, that would blow the fuse. The outside of the socket is a ground. The bottom center is power.

[Cody2289]

I have the socket removed so it’s just the wiring harness. If the socket is plugged in, it blows immediately (even if nothing is plugged into the socket). What I probed with the multimeter was the wiring harness plug that cigarette socket would plug into. Maybe that was pointless.

[kamzcab86]

[Cody2289]

Yeah I sorta figured that out after I posted, I got constant power on the yellow wire but didn’t test the red with the engine running. When I tried tapping the radios fuse with the engine running, I couldn’t get it to read power (granted there’s a plastic tab that seems to be there to prevent accidentally touching it)

I was also hoping the short was inside the cigarette lighter but I think since touching the plug with the multimeter caused instant blown fuse, my short still exists. (Unplugging the cig lighter stops me from blowing fuses but radio is still dead)

[DanHoug]

[Cody2289]

Thanks for all the input, I haven’t used a multimeter in 10 years, I have it set to 200 dcv but I do have the red probe in the 10a slot I guess. I’ll watch some videos to see if I can remotely know what I’m doing here

[MarkWard]

I recommend a 12 volt testlight for troubleshooting electrical problems especially for beginners. Voltmeters have their place, but when testing for power and ground my choice is a test light.