1957 courtesy / map light

jimrob01
Last seen
Joined
Dec 9, 2018
Thunderbird Year
1957
I'm new to the T-Bird hobby and we love our '57 T-Bird ....which for some reason has no working interior courtesy lights. Can anyone tell me if there are supposed to be interior lights other than the map light in the dash? Also, how to remove the map light out of the dash for servicing? I am reluctant to start prying the lens or bezel for fear of breaking something. Thanks.
 
I'm new to the T-Bird hobby and we love our '57 T-Bird ....which for some reason has no working interior courtesy lights. Can anyone tell me if there are supposed to be interior lights other than the map light in the dash? Also, how to remove the map light out of the dash for servicing? I am reluctant to start prying the lens or bezel for fear of breaking something. Thanks.

I took my 1955 apart many years ago. I only remember that one light in the center of the dash. If I remember correctly the switch is a three position switch. Off/on when doors open/on, I am finally in the process of working on my little bird. My plan was to add a light under the dash at each side to light the floor area when I open the doors.
 
The fuse on the headlight switch only powers the courtesy lamp in the dash and the door jamb switches. If this is blown, check the wiring to the map light and door switches for bare wires especially where the wires exit the kick panels and enter the door jamb.

I removed the interior light switch a couple years ago and overhauled it, because the switch was difficult to move. The switch is a two position switch, either on with the doors open or on all the time. After you remove the ash tray assembly, you will see that the switch is held in place behind the dash by a metal plate that is affixed to the switch by two phillips screws.

Attached are some pictures of the interior light switch.

000_5964.JPG 000_5965.JPG 000_5968.JPG 000_5969.JPG

doug7740
1955 Thunderbird Blue
 
My problem is that the map light assembly itself apparently is not grounded. If I ground the bezel, the light works. I just didn't know how to remove the light or how to get at it from the back to see if the ground wire is even plugged into anything. I will remove the ash try assembly and see where I go from there. Thank you for this info.

What's the best way to remove the plastic lens from the light housing? I don't want to pry on it without knowing what holds it in and I can't find anything in the shop manual.
 
I thought about doing the same thing regarding the addition of R&L courtesy lights under the dashboard. The '65-'66 Mustangs I've owned over the years used a simple light bulb in a fixture on each side. As I remember, these hidden under-dash courtesy lights mounted with a single vertical screw. It would be easy to mount one on each side and tap into the map light for power. It may require increasing the size of the fuse, but I'm not sure about that.
 
I made this map light service sheet for my files and I attached it here for anybody who wants to make a copy. Thanks for all your help, guys.
maplight-servicing.jpg
 
Last edited by a moderator:
jimrob01,

When I posted my reply, I forgot to mention that you have to remove the radio to gain access to the two phillips screws. If you ground the bezel and the light works, I would check the ground wire under the one mounting screw. Since I was at the shop today, I took this picture of the courtesy light mounting from the dash that I have removed from a 1955 Thunderbird that we are restoring. In the picture you can see the ground wire attached to the mounting screw.

Interior Light.JPG

Also, the plastic lens cannot be removed from the housing without disassembling the courtesy light.

doug7740
1955 Thunderbird Blue
 
jimrob01,

When I posted my reply, I forgot to mention that you have to remove the radio to gain access to the two phillips screws. If you ground the bezel and the light works, I would check the ground wire under the one mounting screw. Since I was at the shop today, I took this picture of the courtesy light mounting from the dash that I have removed from a 1955 Thunderbird that we are restoring. In the picture you can see the ground wire attached to the mounting screw.

View attachment 2833

Also, the plastic lens cannot be removed from the housing without disassembling the courtesy light.

doug7740
1955 Thunderbird Blue
Thank you for some great information. My light switch fuse kept blowing and when I reached up under the dash I could feel a bare male bullet connector. Apparently many years ago when I removed the radio to replace the speaker I apparently pulled the connector out where it ties into the bulb wire and was shorting out. When I pulled the ash tray and radio I discovered Also that wire is only holding on with a couple of strands so I need to pull the switch to re-solder it.
 
Well it's happening again. Fuse is blown again. Dead short. Guess I'll have to pull the radio and ash tray again as my soldering job may have failed somehow and trace the wire. All wires feel intact. Only thing I can think of is that I recently re-installed my converted clock and may have knocked something loose after working well for months. The lens just snaps in with tabs but the bulb needs to be replaced from the back just like all the other dash lights.
 
Well it's happening again. Fuse is blown again. Dead short. Guess I'll have to pull the radio and ash tray again as my soldering job may have failed somehow and trace the wire. All wires feel intact. Only thing I can think of is that I recently re-installed my converted clock and may have knocked something loose after working well for months. The lens just snaps in with tabs but the bulb needs to be replaced from the back just like all the other dash lights.
I think I've got it sorted out. I pulled the ashtray and radio. Traced the wires as much as possible visually, couldn't find anything out of order. ( good chance to tidy up the wire harness a bit too.)
Disconnected the battery and clipped my OHM meter to the fuse clips. High resistance. Started manipulating the door switch and the meter was going all over the place. Popped it out and squirted PB Blaster in both ends. Resistance came down to a steady 9-10 OHMs. Did the same with the dash switch. Same result.
My question is; is 9-10 OHMs about right to power the bulb? Also I looked at the fuses I had popped none of them were over 4 amps. Looked it up as getting low on fuses and should be 7 1/5 amps. Also a factor even after working for months.
 
pull the lamp bulb and check the resistance,
seams a bit high but don't know for sure
I would expect 2-3 ohms
with the lamp out you can ring out the wires individually
 
pull the lamp bulb and check the resistance,
seams a bit high but don't know for sure
I would expect 2-3 ohms
with the lamp out you can ring out the wires individually
I will pull the bulb and check it's resistance and then apply some di-electric grease to the bulb and socket while I'm at it and easy to get to.

Here is my progress report. After letting the circuit & switches sit overnight, Still around 9-10 Ohms resistance. Checked the bulb 1-2 Ohms resistance. Lubed up the bulb, socket and mounting points with di-electric grease. Re-installed and now only 3 Ohms resistance working either switch. Replaced the fuse with a 7 amp that I had and the map light has never been brighter. Yellowed by age and can get a replacement lens for $6.30. Maybe on my next order.
For anyone who doubts the use or purpose of di-electric grease, use it on EVERY electrical connection you touch. Just read something in a Hemming's article that it is even more critical on electronic ignition module mounts, it also aids in transferring the heat and continuity from the module to the mounting point, heat is the biggest reason for failure of electronic ignitions.
 
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