I recently purchased a 1972 Cutlass and noticed that the radio and inside lights were not working. I checked the fuses and saw that one was blown and when I replaced it everything worked fine for a while now it has blown again. Any ideas what may be causing this? It has an aftermarket radio that was installed before I purchased it but it seems to work fine.

 

Somebody installed a radio in your car before you got it.

Nobody, probably including the person who installed it, has any idea what they connected to what, or how they connected it.

It may or may not be connected to the fuse that blew (which, incidentally, you have not identified), so the radio may or may not have anything to do with your problem.

Sounds to me like you need to get under the dash, start following wires, and see what's going on. I'd recommend first determining which fuse it was that blew, then checking the wiring diagram in your Chassis Service Manual to see what's connected to it, then seeing how the person who installed the radio screwed that up.

- Eric

 

Sounds to me like they hooked the radio to the light fuse, which is not meant to supply this much current. Follow Eric's advice and trace the wiring.

 

Specifically, WHICH fuse was blown? The radio operates on a different fuse from the radio lights (and an aftermarket radio may be wired differently from stock, anyway).

Determine which fuse is blown, open the wiring diagram in the Chassis Service Manual, and start tracing wires until you find the intermittent short.

Would it happen to be the Tail Light fuse that you replaced?

 

ttt
The fuse that keeps blowing is the one for the clock, lighter and courtesy lights. The lighter is not stuck, and the clock didn't work before the fuse blew.

 

Well, when you look at the wiring diagram and trace the circuit, you'll find that the trunk lamp feed is also on that fuse. Any chance that wire is pinched and shorting out? Has this circuit been tapped into for some non-OEM accessory, like a stereo? We've done all we can by remote control. You need to get the wiring diagram and trace the wires until you find the short.

 

+1.

Only you know what accessories have been connected to your car and how they've been connected.

Start going through the circuit until you find the offending item, whether original or aftermarket.

- Eric

 

Check the prongs in the lighter to make sure they did not get mashed against the case. Sometimes this happens when pushing the lighter in to far ot plugging in another device incorrectly - like not straight in.

Also make Sure that all courtesy light bulbs have the correct ones installed. Installing a single pin bayonet bulb in a two pin socket will short the two prongs out and pop the fuse.
This happens often as parts stores often sell owners the wrong bulbs. SOme have never even seen two pinned based bulbs before...

 

also, check inside the lighter to make sure nobody dropped anything into the socket.


bill

 

Great sharing.Nice.

 

When you have figured out which circuits are protected by the offending fuse disconnect all of them (make a careful note of each one so you can reconnect them), then connect them one at a time until you find which one is causing the fuse to blow.
Before reconnecting them use a digital multimeter to check if any circuits are shorting, they should all show some resistance, a 5 watt bulb about 0.4 ohms, a switched circuit in the off position should read infinity, anything showing zero resistance is probably the faulty one.

Check them all, you might have more than one short!.

Roger.

 

Thanks
for all the info anf help. I will try to start on it this weekend.

 

what did it end up being? i'm having the exact same problem right now and can't find the short.

 

I was so busy over the summer that I never got a chance to fool with it.