2nd Gen Non-Engine/Transmission interior lights

[PaulG]

okay i'm having a problem with my interior lights staying on.



dealer told me to try unplugging the light switch and door pins and if the lights went out it was one of them. i tried this and the lights stayed on. i tested the light sockets (map lights and dome) all is good there. So now i'm lost on what it could be. obviously it's getting power from somewhere so anyone have any idea's?

 

[tp0d]

bad contact in your dash dimmer/interior slider? do you use that switch a lot? might want to check there also... (prolly already have tho. . but i duno)



-j

 

[PaulG]

no i totally unplugged the light switches inside the cab, it's all one unit the headlight switch and slider so it's not the slider. i was wondering maybe if there is a relay in the system somewhere?

 

[Thomas]

... i tested the light sockets (map lights and dome) all is good there...

Just what sort of a test did you do?



I think you'll find that the map lights/dome light circuitry is quite complex, involving the Central Timer Module (CTM) also called the Integrated Electronic Module (IEM). This module is the device that controls wiper delay, heated seats, interior lights on for set time after door is closed, all those annoying chime warnings, and a lot of other things.



My limited reading of my model year 2000 factory service manual suggests that the interior lights are on switched-ground circuits. Twelve volts will always be present at one terminal of each bulb socket. The bulb will light when a path to ground is provided at the other terminal of the socket. A simple observation (with a normally functioning truck) that should convince you that the interior light wiring is a bit more complex than an ordinary flashlight is to watch what happens to these lights when you open the door and close the door - the lights should remain on for a set period of time. Again, open the door and close the door and then turn the key to the run position - the lights should remain on until the key is turned. All of these events are controlled by the CTM.



Your problem could be as simple as worn insulation and shorting of a wire from the driver's door jamb switch or a defective switch. Or it could be the CTM.

 

[ntillm01]

i was wondering maybe if there is a relay in the system somewhere?

Like Thomas wrote, yes, there is a relay in the system called a CTM. It's a big fancy relay, but still a relay. (assuming you have an uplevel enough truck to have a CTM)



If you unplugged the door switches and the light still stayed on, I would rule those out. Some other input to the CTM is making it think the dome lights should be on. You need to figure that out.



You never mentioned, but do they ever turn off (like when you turn the key on?)



Also, I'm guessing you already checked, but is it that the map lights are on? If those are clicked on, they stay on regardless of what the CTM is doing.

 

[PaulG]

i guess first off i have an SLT laramie not leather. second i bought the truck used but the interior lights never stayed on after opening and closing the door they just simply turn on and off just like a switch. i've heard of people saying about the light staying on after using the remote entry which i didn't have from the factory so maybe my truck doesn't have that "security" lighting.



yes i check the switches for the map lights they are not slicked on wouldn't matter anyhow if they were or weren't cause the dome is still on. i unplugged the map lights just to take them out of the equation. i guess i'll have to try to find that relay and start from there to see if thats bad if not like thomas said i kinda thought it was going to be a veyr complex wiring area! uuugggg :{

 

[ntillm01]

You'll find it. Just a matter of patience. Do you have a service manual? A schematic would help you out a lot.

I would think a SLT Laramie would have the "smart" CTM, but the way you describe the operation (dome light goes out immediately with a door close) your's may not have it. In that case, you would have a simpler system that only uses dimmer switch and door switches and the wiring inbetween. In my experience, a wire short turns out to be the culprit most of the time for these things.

Any aftermarket what-nots installed that maybe got screwed through a wire harness during installation? Aftermarket alarm that's tapped into the system (that you don't know about because the prior owner lost the key fob)?

 

[Thomas]

All model year 2000 Rams have CTM's - different flavors depending on electronic equipment.



CTM's used model year 2000:



56020157AC Without Keyless Entry

56045448AB Up to 10/07/99, with Keyless Entry

56045448AC 10/07/99 & After, with Keyless Entry

56045999AD With Heated Seats

 

[PaulG]

well i got inter. wire dia. from dealer going to take a look this weekend.

 

[FFL8N]

Same problem

OK. . I just did a search and found this post. I am having the exact same problem. My interior lights stay on. All 3 of them. I actually bought a new door switch and tried it on one door at a time. No luck. I then took both door switches off and the lights still stayed on. Then I also removed the light dimmer switch from the console. The lights are still on. Finally, I had to remove the 3 bulbs from the lights so that I can still have a radio. Did anyone ever find out what might cause this. I have the slt with leather. It is a manual though (if that changes anything).

 

[tURBOdIEZEl]

i was having the same problem... . and was getting tired of worring about my battery going dead, so i just took all the light bulbs out... . not a problem since :-laf

 

[FFL8N]

lights out!!

Thats funny... thats what I have done also... Am looking for a better fix.