courtesy lights 69 c3

[Tom S.]

I have been working on the courtesy light't and this is my problem.I have a master disconect at the battery on the positive wire.It works fine.When the engine is running and the master is in the off position the cortesy lights work fine.When the master switch is turned on and the engine is running or not the courtesy light will not work. Where do I start?I hate wiring problems.
Thanks in advance Tom Stanton #41491

[Jeffrey S.]

Re: courtesy lights 69 c3

Tom:
First a question. Why would you turn your switch off with the engine running? These switches are usually used to disconnect the bsttery when the car is NOT in use. I have one on my '69 and I think it's great. I use it in conjunction with a "Battery Minder" and the battery is always fully charged. I would suggest that you put the switch on the negative side of the battery. If you swich the positive side I think it would still be possible to have a short cause a fire even if the switch is off. I'm not certain and I'm sure someone will correct me if I'm wrong.
Jeff

[Terry M.]

Re: courtesy lights 69 c3

Jeff,
It doesn't electrically make any difference which terminal is disconnected. An open circuit, is just that -- open. When disconnecting one side of the battery, one is creating an open circuit.

It may make some difference for reasons of clearance or ease of installation, or ease of operation, however.

It is not a good idea to disconnect the battery from a car while it is running, and I can almost guarantee expensive electrical failures if one does it to any car 1980 or newer.

[Jeffrey S.]

Re: courtesy lights 69 c3

Terry:
Thanks for making the correction. I was always told to switch the negative (or neutral on 110V) and never the positive (or hot).
Jeff

[Tom S.]

Re: courtesy lights 69 c3

Jeff
I had just put a new battery in the car, My son was helping me do some thing's.I had the car running in the garage and my son turned the switch and said hey Dad what is this switch for?This was when I noticed the courtesy light's on. I checked the light switch and it was off.Then I checed the door switch and it worked fine.I then turned on the master disconect and the lights went off.It was a freak thing, but now I am curious as to why they worked this way but not before. Is it a ground problem?The lights have worked with the light switch all along.please advise.
Tom

[Terry M.]

Re: courtesy lights 69 c3

Jeff,
If you were told to switch the neutral on a 110v circuit -- you were told WRONG. One of the first things one learns as an electrician is never ever switch or fuse the neutral. It even makes me uncomfortable that switching the negative is common in automotive circuits, but that is often done. The negative of automotive circuits is not the same as neutral in household electrical circuits.
I could offer a long-winded explanation of why you don't want to switch the neutral on a household electrical circuit, but to stay on topic I'll not do that, and ask you all to trust me -- don't do it. It is a major safety issue. Safety as in it could cost you your life.

[Terry M.]

Sorry Tom....

I don't know why the operation of the courtesy lights changed.

[Jeffrey S.]

Re: courtesy lights 69 c3

Terry:
Now that I think about it I realize that you are very right. I always switch the hot in 110V. I don't know what I was thinking (maybe I wasn't thinking) when I wrote that post. I was thinking that almost all the switches in an automobile are ground switches. Maybe I shouldn't generalize. Thanks for the responses.
Jeff