Dome light...

-
blue1973duster

blue1973duster

Member
Joined
Apr 29, 2011
Messages
11
Reaction score
0
Location
Miami
Can anyone help me figure out why my dome light one turn off after closing the door? I took the bulb out and put it back in and it works fine the first two times and after that it stays on again???
 
Useable wiring diagrams from MyMopar:

http://www.mymopar.com/downloads/1973/73ValiantA.jpg

http://www.mymopar.com/downloads/1973/73ValiantB.jpg

came from here:

http://www.mymopar.com/index.php?pid=31

Generally, YELLOW is the ground side of the dome light, IE the door switches ground that side to activate the light. Yours may have a time delay relay

I haven't researched this completely, and do not have a 73 shop manual, it might also be a backfeed problem if you have the headlight warning buzzer.

Start by making SURE your headlight switch dash lights dimmer is NOT over into the courtesy lamp position, and nex disconnecting one door switch at a time, as well as the delay relay if you have it, and the warning buzzer if you have on.

I SURE WISH you guys who have 73/4 shop manuals would get ahold of Abodyjoe and post 'em here.
 
Thank you! I'll try it out hopefully I can figure it out. Diagram helps a lot! By the way, how do I know if the courtesy switch is on? My dad never had a bulb for the dome in 10 years so I'm not really sure?
 
When you twist the light switch it controls the brightness of the dash lights. All the way HARD to the left, you'll feel a "click" at the end, and that is what turns on the dome lights.
 
I agree check the door jam switch, with door open push it in all the way does the light go off? close that door and check the other one. also is the dimmer turned off?
 
The extreme case is melted wiring under the dash. Our 74 Satellite had the typical issues with the 35 year old bulkhead connector. The wiring to and from the ammeter overheated from oxidation of the connectors and fused to the dash and dome light wiring under the dash. Both sets of lighting backfed and would stay on.

Always a good practice on these older Mopars to check your wiring to your bulkhead connector and look for any distorted or melted insulation.

BHCwiring-1.jpg


wireclump.jpg


May not be the problem in your case but still a good idea to check it out and look at your wiring. The donor car we got with the 74 was also melted. It was a lot of work but we fixed the wiring and it's back on the road. Better to isolate it before it becomes a huge issue. There's lots of information on the web on how to modify the wiring to avoid it happening again.
 
We'll I've been messing with it now and I can't get it to turn on now...
Could it be the switch itself? I didn't even know when you turn it it controls the brightness of the dash lights because it never did anything when I would turn it.
 
When you say you've been messing with it what exactly do you mean, the headlight switch or the door jam switch?

Do you have a factory wiring diagram? That would help a lot to identify the wires. It does sound like a door switch and that's where I would look first.

The door switch interrupts the ground. If you remove the kick panel you can usually get to the wiring that feeds into the switch. It could be either front door switches if that's where the problem lies. If you unplug them, you can check their continuity to the ground with a meter. When pushed in they should open the circuit and you should lose continuity.

If the door switches seem to be working properly you can try a headlight switch from a boneyard. I don't know how well the supply is out there but all the yards that have older cars out here usually have several mid-70 a-bodies available.

The headlight switch has a coil of wire that works as a rheostat to dim and brighten the dash lights when you spin the knob. When you turn it past the brightest setting you will feel it click as it makes contact and the dome light will come on if it's working correctly.

This is likely a little different than yours but you can get an idea. http://www.ebay.com/itm/Nos-Mopar-1...Truck_Parts_Accessories&vxp=mtr#ht_500wt_1081
 
Some models had a timer that would hold the dome lamp and the ignition switch lamp on after the door closed for :xx seconds or until the ignition switch was turned to on.
Do the door jamb switches have one wire each or two ?
 
Door jams have two wires each to the switch and also, when I turn the head light switch nothing happens with the dimming of the lights on the dash...
 
blue1973duster said:
Door jams have two wires each to the switch and also, when I turn the head light switch nothing happens with the dimming of the lights on the dash...
Click to expand...

Your headlight switch is malfunctioning.
Replace that and go from there.
 
The dash light dimmer feature in the headlight switch and the dome lamp are not related.
Turning that knob far enough will toggle a tiny switch built in the headlight switch that will supply a ground to the dome lamp just like the door jamb switches do when you open the door.
I solder a jumper over the dimmer reostat when it fails which gives me bright as possible dash laights no matter where that knob is turned to but, I can still turn it to far right and toggle the dome lamp on.
if the dome lamp was working before and stopped, the problem may be as simple as ablown fuse.
 
It started turning on again but now its very dim. When I turn the switch all the way to the left and it clicks nothing happens? could it be a bad ground?
 
blue1973duster said:
It started turning on again but now its very dim. When I turn the switch all the way to the left and it clicks nothing happens? could it be a bad ground?
Click to expand...

Lets forget the headlight switch for a short time. The ground path is through the door jamb switches. If the light is dim when you open the left door, open the right instead or both and see if it gets brighter.
 
Possible corrosion at the connector in the kick panel. If you have a voltmeter/multimeter measure the voltage at the light bulb. See if it is anywhere near battery voltage.
 
blue1973duster said:
Its dim with both doors open.
Click to expand...

The reason we "got off" on the headlight switch is that you said it was staying ON

The way the dome works is, the bulb is dual contact and is NOT grounded at the socket. It gets power from the fuse box, goes up to the dome light, comes back down (yellow) and goes off to all the switches, doors, headlight, which ground the lamp to turn it on

You could have poor supply voltage TO the bulb, or a poor ground at one or both of the switches, or a poor connection at the harness connector up by the left kick panel.

To check for a poor ground at a door, go over to the OPPOSITE door and bring the switch/ wiring out where you can get to it.

Open the other door, notice that the lamp IS dime, and measure from the yellow to ground on the switch you have out. If you see a voltage reading there, 1/2 volt or more, you indeed have a poor ground at the other switch.

If not the trouble is elsewhere.

Go up and inspect the socket. Scrub the socket contacts and the bulb contacts CLEAN. Be sure to pull the fuse or unhook the battery.

To check a voltage problem is MUCH more difficult because "you can't get" to anything.

One place to check voltage is with the dome light ON and right at the fuse box.
 
Per your first post, I still suspect there is a delay timer in the mix. I've seen those timers and aftermarket burglar alarm systems make the dome lamp do strange things.
A couple of places to inspect wiring connections are on top of the lamp fixture and inside the trunk near the left wheel house. Trunk lamps are wired into the same circuit
 
You must log in or register to reply here.
-

Back
Top