I know this has to be something to do with the door, but I'm not sure where to check and how to go about fixing it.

When I open up my driver's side door only my rear driver's side back seat light goes on. The door light does not and neither do the lights under the dash. When I open up my passenger side door all of the lights go on (both rears, both doors, and both lights under the dash). So, there must be a problem with the sensor on the door, but why would the rear light for the driver's side go on and not the door or the other lights? Any idea what might be causing it and how to fix?

Thanks,

 

try http://www.themustangshop.com/resources.cfm, click on 1970 wiring diagram and unzip the information on page 2. quick glancelooks like the black/blue wire is common to the the left courtesy
light and has a male/female connector associated with it. check the connector. also, your courtesy lights must have a good solid ground at the bulb holder to function properly. have you check the bulb?

 

Have your lights always been this way?

Frankly I am baffled by your issue.

If these lights are wired into a common circuit, all of the lights should light, or none of them should light.

 

Very odd indeed, with the exception of 1 blk blue segment from the left door switch, all of the courtesy lights are on a common circuit. There is also a separate green yellow wire for power to the door switches but since the left wire feeds the headlight switch and right door switch, it's probably OK.

Take the left door switch out and check for 12 v at the green yellow wire, if OK, jumper the green yellow to the blk blue wire and look for all of the lights, if all lights are on the problem is the switch, if not, there's a factory disconnect/splice pointin between the headlight switch and the door switch that needs to be looked at for a broken wire(or just look for 12 v at the head light connector with the left door open and the right door closed). Its just a matter of following the circuit in the WDM link that Groho gave you. good hunting.

 

I just replaced the bulbs in the rear of the car and checked those connections which are fine. It has to be something with the door opening switch. If I can't figure this out myself, what kind of place would you reccomend me to take the car? A regular mechanic shop or a ford dealership?

 

IMO a Ford dealership would not have any idea of where to start...

A generic shop would bea grab bag.... I would worry that whoever workes on the car might create more issues than you have now....

There are a lot of technicians out there who don't know much about auto electronics,,,, might get someone who just wants to cut and splice,,,,

You might want to trace the wires back from the lights on your own, and if you don't find somthing unplugged, leave it alone....

I don't think it is a switch issue.....