dome lights not working 100%

[JK930]

Hi
i have a 81 930 coupe.
my 2 ceiling dome lights only work when doors are opened. ( i am happy about that).

so doors work
always off work
always on do not

I can not get the always on position aka, "map light "to work on either side.

I did remove both to have a look and clean the contact point.

could both light housing be bad in that one position?

any help would be appreciated

also where do i find a good wiring diagram for the 1981

[DRACO A5OG]

Check the door jam switches.

If they are there, remove the rubber covers carefully.

Use a 10MM deep socket and loosen the switch, then stop and get a 10MM box wrench and a needle nose pliers to hold the plunger as you slowly use the box wrench to remove the switch. The purpose of this is to keep from twisting the ground wire off and losing it in the pilar, NOT GOOD.

Clean the back side of the plunger very will as well as the pilar area of any rust and or debris.

That should cure the in-consistent light function via the door.

[JK930]

the door light and pin switches work fine on both sides.

it is the "always on" position that does not work

[DRACO A5OG]

Oh I see, my bad.

Okay then it is a ground issue with the dome light itself, basically not meeting ground to close the circuit to "light on" always mode. Find your wiring diagram to see if domes were tampered with in the past.

[Joe Bob]

The bulb(s) may have corroded contacts. AND how are you positive the pin switches are OK, they lie like sheeps and goats do......

[JK930]

each time i open the doors either side the light Does come on. no problem the
only when i am seated in the car doors closed i reach up tilt the lens to the "always on " position and the light does not come on.
flip the light lens to the door position open door light comes on.

so pins switches OK
light bulbs OK

my guess that it is the actual dome light housing that is not working. but before i spend $80+ dollars each i just wanted to double check

[Joe Bob]

OK, if it's a replacement fixture it's a known defect on the new repros. Pull the fixture and test it. Trust me.

[Algernon]

You must have a good ground to put the light on in that position. All you need is to insure the switch contact really grounds the bulb in that position. Either the contact in the switch is corroded or the ground (through the screw and housing) is corroded. Don't spend money replacing anything, just give them a good clean!

[Joe Bob]

Willing to bet money on the fixture being bad....

[mhackney]

Originally Posted by JK930

my guess that it is the actual dome light housing that is not working. but before i spend $80+ dollars each i just wanted to double check

Do you have a voltmeter? Even a cheap $10 can tell you exactly what's going on. You have power to the lights - known. The switch mechanism inside the lights is very simple mechanical and completely exposed when you remove the unit. Use a 9V battery to test outside the car. Hook up the battery, then probe away with the meter. This is how I found the same exact issue on my Cab's overhead light a few years ago. Then last week I finally chased down my door switch problem.

If you are getting current to the unit and it lights in one position and not the other, you most likely have a contact issue. Corrosion can be difficult to see and it does not take a lot to insulate. How about posting a photo of the open mechanism.

[gumby]

This thread is very timely...
I too am having the same trouble but I've been to lazy to poke around it

[mhackney]

We hope we can illuminate you and the OP!

[gumby]

shouldn't the lights also come on when you rotate the head lamp knob fully ?

[mhackney]

On my ex-70 and my current 83, it did not. The headlamp knob rotation dims the dash lights but doesn't turn on/off the overhead light/s .

[JK930]

So I removed the light fixture for the second time

once again :

always off...................ok
Lights On with door open.......ok
( both doors work with pin switches , both lights come on with either door open. OK)

always On... aka. map light ...... not working

I am using a Snap On Multi Meter and Continuity Tester

I disassembled the light as show
cleaned all the contacts with a wire brush
also cleaned with CRC Electronic Contact Cleaner & blew it out with compressed air.

with the continuity tester.

the light will only only come on in the middle position ( doors open)

rock switch to left or right position.... nothing.


reassembled fixture
retested on bench.... Only the middle position (door open) would show continuity
rock switch to left or right position.... nothing.

put fixture back in car same results


extremely simple construction

i am wonder if ..maybe..possible..there is no map light feature.. hmmm














the 3 contact legs on light fixture comes in contact with the terminal on right
top position ..blank...middle position 1 contact...lower position ..larger contact.

am i missing something

[Joe Bob]

So......the fixture is bad......%^)

[mhackney]

Perhaps but use your multimeter to verify where you see voltage at each end of the contacts, where the rivet is - both sides of it. It really is a simple mechanism. Imagine where the current should flow in the always on position and probe until you find the fault. Another trick is to use a short wire and jump from positive to the + side of the bulb and it should light. If not do the same in the ground side. Once you get it to light move the wire back to the next junction or contact until you isolate the problem.

[86 911 Targa]

Originally Posted by JK930

Hi
i have a 81 930 coupe.
my 2 ceiling dome lights only work when doors are opened. ( i am happy about that).

so doors work
always off work
always on do not

I can not get the always on position aka, "map light "to work on either side.

I did remove both to have a look and clean the contact point.

could both light housing be bad in that one position?

any help would be appreciated

also where do i find a good wiring diagram for the 1981

^^^^^
For our M/Y '86, but should be close for the M/Y 81.

I think your switch is defective.

Best,

Gerry

[mhackney]

Ok, firstly, see the tips of the orange and green arrows - make sure those areas are very clean. Use a pencil eraser or something similar to polish to a shine. These contacts look a little dirty.

Next, see the white plastic piece by the green arrow - the outer edges have ridges or detents. These create the 3 positions for the switch action. The way this works is, the brass leaves with the yellow and red arrows are simply springs that ride in these detents. The contact is actually made by the brass leaf at the orange arrow contacting the brass contact at the green arrow.

So what is likely happening is that in the always on position the outer leaves (yellow or red) are preventing the orange leaf from making contact. First make sure these contact points are clean then you can carefully bend the leaves. Most likely the center (orange) leaf just needs to be adjusted a bit but if that doesn't do it, determine which of the others is the constant on leaf and bend it carefully AWAY from the white plastic part with the detents. Also, the contact at the green arrow may need to be bent out slightly. The idea is to get the orange contact to make with the green contact when either the yellow or red leaf springs are in their "on" detent settings.

This is a simple mechanical switch that is quite serviceable of you take your time to adjust it. One tip, make sure the white plastic part is nice and clean - use a toothbrush. Once you have the switch working use a teeny tiny dot of white lithium grease on the outer detent tracks to get a smooth operation.

[mhackney]

PS if you do decide to replace one or more of these, I'd like to have these so I can photograph clearly and adjust them to make a good post about this. I no longer have my 70S that has the same style rocker switch and the 83Cab rotates around the long axis (but a similar fix worked for it too).