66 Chrysler 300 interior lights
- Thread starter Umeracle
- Start date
D Cluley
Active Member
First of all, let's clarify. I assume you mean the lights for the speedometer & other gauges. Is that correct?
They are supposed to light up when the parking lights or headlights are on. The brightness is controlled by turning the knob on the light switch. That adjusts a rheostat inside the light switch, and those can get dirty or go bad, so that is probably the most likely culprit, but let's check the easy stuff first.
1. Do any of the other dash lights work? (heat controls, radio, clock) Those are on the same circuit, so if any work, then the problem is with individual bulbs being burned out, or connections with the instrument cluster.
2. Do the inside dome light or the brake lights work? If yes, then you have power going into the light switch. If not, check Fuse E. They wiring diagram in the Factory Service Manual has them identified by letters, hopefully so does the fuse block under the dash. If not it will be one of the 2 fuses that are second from the end.
3. Then check Fuse F, the one on the end. That is in the circuit between the switch and the dash lights.
4. Try turning the dimmer switch back and forth. Sometimes if the rheostat is dirty or worn, there will be some spot in the rotation where it does work.
5. If that doesn't work, your best bet is either trying a different light switch, or unplugging it, and testing with a temporary jumper to bypass the switch. I'm guessing your local parts store in the UK doesn't have 50 year old American light switches in stock, and the jumper trick is a little complicated, so let us know if the easy remedies do anything first.
They are supposed to light up when the parking lights or headlights are on. The brightness is controlled by turning the knob on the light switch. That adjusts a rheostat inside the light switch, and those can get dirty or go bad, so that is probably the most likely culprit, but let's check the easy stuff first.
1. Do any of the other dash lights work? (heat controls, radio, clock) Those are on the same circuit, so if any work, then the problem is with individual bulbs being burned out, or connections with the instrument cluster.
2. Do the inside dome light or the brake lights work? If yes, then you have power going into the light switch. If not, check Fuse E. They wiring diagram in the Factory Service Manual has them identified by letters, hopefully so does the fuse block under the dash. If not it will be one of the 2 fuses that are second from the end.
3. Then check Fuse F, the one on the end. That is in the circuit between the switch and the dash lights.
4. Try turning the dimmer switch back and forth. Sometimes if the rheostat is dirty or worn, there will be some spot in the rotation where it does work.
5. If that doesn't work, your best bet is either trying a different light switch, or unplugging it, and testing with a temporary jumper to bypass the switch. I'm guessing your local parts store in the UK doesn't have 50 year old American light switches in stock, and the jumper trick is a little complicated, so let us know if the easy remedies do anything first.
Thank you so much for this - yes the speedometer and gauges. Will try and check all of this when i get home
Any luck?
stubs300
Senior Member
One day it works, the next it doesn't, and you did nothing to cause it. I hate dealing with those kinds of repairs! I have the same issue with my 66-300, I haven't looked that deep into it yet. I'm guessing that it's the switch as twisting it does nothing to get them working. 
So what you said helped - I can see light in the dashboard but sometimes its bright but it keeps dimming down. I don't drive the car at night as i found that sometimes when I come to a stop my car dies out. Front headlights are also bright but most of the time dimming down and back to bright then back down low.
Could this be the battery needs replacing?
Sounds like a charging system issue. You may want to start a new post titled "lights dimming". The guys here have almost all been through it.
Beyond my pay grade......
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