1961 Cadillac body fuse issues

[Andrew Trout]

In the never-ending quest to have a sorted 1961 convertible I'm tackling more interior lights, specifically the ones on the main body feed. Map light, courtesy light, ashtray lights, and clock light. None of them work right now, but I remember the ashtray lighters working when my Dad and I first reassembled the dash. I found and replaced the blown fuse only to have it blow after a few minutes. I searched the forum and found this thread about the same problem in a '62 convertible http://forums.cadillaclasalleclub.org/index.php?topic=137579.0 which gave me some ideas to try.

I started off by replacing the fuse with a resetting fuse. I reconnected the negative terminal on my battery, and started seeing what happened. 

What I found out:

Working map light when manually turned on.
Inconsistent courtesy light when manually turned on. The bulb works when I press hard on it, or firmly shove the fixture towards the passenger side of the car. I believe the bulb is installed wrong and not contacting the base of the socket. Removal will be tricky, the bulb is really stuck
Working glove compartment light
Power/continuity at the driver's side ashtray light
Power/continuity at the passenger's side ashtray light
Power/continuity for the clock
Power/continuity for the clock light
No power/continuity for the trunk light

What I don't have:
Working automatic courtesy/map light
Working automatic rear courtesy light
Working clock
Working clock light
Working ashtray lights on either side
Working rear speaker (I believe the speaker is good, haven't tested it in a while)
Working trunk light

Other notes:
I have a broken wire for the rear license plate light. It's snapped off right at the terminal. I'm working on repairing this, but will need the help of a friend.
The drivers side door switch appears to be stuck in the door closed position, the passenger door switch appears to work correctly.
The map light got extremely hot (I burned my thumb turning it off) so I replaced the LED bulb my Dad installed with an incandescent bulb. I did not retest the light afterwards. The resetting fuse never tripped, so I removed it once I was done testing.

Based on my limited knowledge, this is a grounding issue, as some lights are working, while others are not even though they have power. Any ideas on where in the harness I might be having a grounding problem?

Also, I'd like to replace the driver's side door switch to help with the courtesy lights working when I get in. What I have in the car right now looks an awful lot like part number 581208. But it seems like part number 4826444 is the correct part for my car. Any insights on this?

EDIT: Looks like part number 1998748 is the original part, and was replaced by part number 4826444 in 1965

Thanks!

[Daryl Chesterman]

Andrew, for the broken wire for the rear license plate wire could you use NAPA part number LS6226?  Sorry, this program will not allow me to post a picture in the format that I am trying to use .  You can Google the part number for a picture.

For your door jam switch, I did an interchange on GM part number 1998748 and it came up with the NAPA part number DJ6300, and that is also the part number when looking it up by application for your car..  There was no interchange for the 1965 part number.  You can Google the NAPA part number to get a picture to see if it is the same as yours.

All of the light bulbs that you are working on are grounded through the lamp sockets, which are grounded through the chassis.  Check all of your chassis ground straps to be sure the connections at each end are clean to bare metal.  Have you checked the bulbs for continuity through them?  Sometimes a bulb can appear to be good but is not.  The door jam switches complete a ground for the courtesy lamp bulbs, so if it will turn, try rotating the plunger in the switch back and forth while the spring is trying to have the switch make contact.  This might remove some corrosion that has accumulated in the switch and allow for a good contact.

If you have some rubber gloves or something rubber that you can wrap around your stuck bulb, that will give you some grip on the bulb to aid in the removal.

Good luck on your electrical problems—it is a labor intensive problem to get them sorted out one by one!!

Daryl Chesterman

 
      

[Andrew Trout]

I'm bringing this back up from the depths of the forum with an update: I didn't fix it, but it's not broken anymore.

A few weeks ago I replaced the door jamb switches. I had two different switches (one in passenger jamb, a different one in the drivers side) which means I'm not the first person to have this issue. I replaced both with reproductions from OPGI. While technically not for a 1961 Cadillac, the switches worked without issue. I had a working courtesy light in the dash. Yay! The fuse blew while driving back to the storage unit. 

Today, I got the car again and went to work. I started off by testing each ashtray light. Check for continuity, then remove the fixture from the dash paneling to check for the light working while connected to ground directly. The passenger side bulb was busted so that was replaced. Once I knew the bulb would light up when grounded, it was finding the missing ground in the dash. Other lights work correctly in the dash so my theory became the repainted dash has paint that is blocking a ground.

I took a small square of coarse sandpaper and rubbed it on the back side of the dash panel the ashtray light fixture fits into, as well as the small hole to remove some paint. After doing that and reinstalling the light fixture and bulb, the passenger side ashtray light would work while in the dash.

I repeated the process on the drivers side and had a working light in the ashtray in short order.

So now the courtesy light works, and both ashtray lights work as well, plus I don't blow the fuse so they stay working meaning the glovebox light and clock light will work as well.

There are still issues to be resolved with items on this circuit. I'm not sure about the rear speaker, and the trunk light has no continuity so that may require some deeper exploration to see if there's a break in the wire someplace. I removed the bulb for the time being. The wiring for the rear license plate light has power at the terminal, but the wire to the light is broken right at the terminal. And I didn't even check the rear courtesy light so who knows how that's doing. Lots more work do it, but it's very rewarding to get a win, no matter how small it is.