INTERIOR LIGHTS

[studequest]

Assuming Bulbs ok and Glove Box/Trunk Lights work and wires are ok

whats best way to trouble shoot interior lights and uinder dash light?

Check Door Switch?

Ground?

 

Thanks

[brad]

Under dash is the only light that goes on with the doors opened. The rear lights are operated by the switches on them.

 

[studequest]

right and none work

? Use test light to see if door switch is bad? 

same on interior lights to see if there is power (assume ignition has to be on?

thanks

[Gunslinger]

A prime problem to look for is bad grounds...the bane of fiberglass cars.  You can use a test light with will tell you whether the light sockets are working properly.  Did you check and see whether the bulbs themselves are good and not burned out?

[studequest]

I definitely will do that of course.. This is a restored car with 800 miles on it that I just purchased.  Owner said he

never paid attention (I always know if I have a battery issue on my 63 R1 because the courtesy light is or is not working

That's what drew my attention to the lights.  I got some extra parts with the car and there were 2 new door switches.

I understand only the courtesy is operated by the door switch.. 

Thanks

[Ron.Strasser]

Power is brought to all 3 lights.  The 1 light that is under the dash board is turned on by bring ground to the light by the door switches.  The 2 interior  lights are turned on individually by the switches on them.

Fist check for power at the 3 lights; 

Then disconnect the cars battery  Then check for a ground at the 2 interior lights

Then or a ground at the courtesy light when a door is open

Ron

[studequest]

Ron.. stupid question

why is the battery disconnected to check for ground?

[Ron.Strasser]

Unless you rare testing for the presence of voltage it is always a good practice to remove any source of electricity while testing. Less chance of letting the smoke out of the wires and maybe confusing the meter.

You are looking for zero (or close to it) ohms between the object you are testing and the grounded terminal on the battery  Or you could test to any substantially grounded metal part of the car.

Ron

[studequest]

Ok.. got the lights working sort of...Changed bulbs

Tried LED's (they bayonets are very tought to push in as are the regular filament bulbs

They function but they do not turn off

There is power to the sockets

Courtesy light wont turn off and neither will interior lights

Wiring looks ok.. whats next?

[Ron.Strasser]

Do I understand you correctly; you are now using LED bulbs in all locations.  For one thing LED bulbs are polarity sensitive. Another it takes a very little of a ground connection to light a LED bulb. 

Being a retired electrician; when we encountered old knob and Tube wiring (all black) we would take a LED test light. (for 120 volts) hold one end of the test lead between two fingers and touch  the other test lead to one of the black wires. When the LED illuminated; we found the hot wire.  Oh by the way we were not in any way grounded standing on a fiberglass ladder.

Still sounds like you have a ground problem.

Ron

[studequest]

Ron

I will use standard  bulbs

Any tricks to chasing down the bad ground?

[R3 Forward]

Ron 

If your power and ground are okay I would look at the swithch.  I have been restoring a 63 and found the internal contact in the switches of all three of these interior lights were corroded.  It is not difficult to disassemble them and sand down the copper contacts reassemble and you are good to go.

 

 

[Ron.Strasser]

If the bulb is good, the bulb socket is good, there is the correct voltage to the correct bulb and the bulb has a good  ground; the bulb has to light If not go back to step one.

To test for a good ground, use a good digital multi meter set to its lowest ohm scale . You are looking for close to zero ohms. If the meter goes to infinity; go to a higher scale until you get a reading.  Then test various ground connections until the ohm rearing decreases. 

You could also run a temporary wire from the battery right to the bulb.

I my self use an auto ranging Fluke that cost less then 100 dollars when I purchased it 15 or more years ago.

Ron

[studequest]

Thanks Ron.. Here is progress

The courtesy light requires a single filament dual terminal bulb

Not sure about courtesy lights but I believe the switch should be cleaned ..The socket seems to work with the dual filament dual terminal bulb and is not controlled

by the switch.. stays on all the time.. So I will clean the switch and test with both bulbs

 

Appreciate your help

[Ron.Strasser]

According to the Avanti service manual both the Dome light and the Map (courtesy) light use the same bulb a Number 1004 which is a single contact.  Ground is via the outer shell of the bulb.

From the drawing I can not tell if the power wire is run through the switch that is mounted on the light assemblies.   

According to the diagram for the Courtesy light power is supplied to the bulb at all times.  The ground for the bulb is via a switch .  You are unable to turn off the courtesy light via the switch on the light assembly In one position the light is on all the time and the other position the light is on when either door is open.

 

[studequest]

THANKS RON I JUST LEARNED THAT FROM CARL THOMS AT STUDE WEST

[George Rohrbach]

If you use a higher power bulb, you can melt the lens. I know from experience.

George Rohrbach

[studequest]

Yes George.. the correct bulb is 1004 dual contact single filament

[Ron.Strasser]

22 hours ago, Ron.Strasser said:

s

I have a mistake in a previous post.  Bulb 1004 is a double contact bulb.  The ground is via one of the contacts not the outer shell of the bulb.  It has been a long time since I replaced any of the interior bulbs. 

Ron

[studequest]

correct .. i discovered that

[studequest]

problem solved

switches bad in courtesy lights.. bypassed the switch and wired to the door switch and under dash switch

Doors open all lights come on

Doors Closed, use courtesy light switch.. Booya!  all works

 

Thanks guys