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I have a 1992 Chevy Corvette. I'm having trouble with all of

Customer Question

Customer: Hi, I am Red. I have a 1992 Chevy Corvette. I'm having trouble with all of my interior light staying on and draining my battery. I think it's a problem with the courtesy light timer module. Do you think that's the problem and tell me where to find the courtesy light timer module ?
JA: Thanks. Can you give me any more details about your issue?
Customer: I've looked all around under the front dash and can't courtesy light timer module.
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Customer: Sure, do you think that is the problem and you can tell me exactly where the courtesy light timer module is and how to fix it.
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Submitted: 1 year ago.
Category: Chevy
Expert:  Reggie Whiddon replied 1 year ago.

Hi I'm Reggie and am glad to help you are u asking for location and or diagnostic assistance just a moment while I access the info,

Customer: replied 1 year ago.
I know the interior lights are staying on when the door are closed and I'm driving. I have made sure that the dimmer switch is not push all the way up on the head light control panel. It just stated doing it and now it draining my battery over night.
Expert:  Reggie Whiddon replied 1 year ago.

Okay I went and looked at the wiring and also the failure pattern reports. I believe what Is most likely your problem Wil be a faulty door jamb switch

Expert:  Reggie Whiddon replied 1 year ago.

Do you know where they are? They are in your a pillar where the door closes and Wil push them shut. You can pull them out and check them

Expert:  Reggie Whiddon replied 1 year ago.

Let's do that first unplug them one at a time one of them should make the lights go out

Customer: replied 1 year ago.
I have checked the door switch and the buttons feel good and still have the a good spring tension ( I have to pull the door panels off to get he switches out). I have also checked the button for the back glass hatch. I think it is the courtesy light timer module because the first couple of time I noticed it was at night and while driving the lights went out.
Customer: replied 1 year ago.
Can you tell me where exactly the courtesy light timer module is located on my car ? I have been doing a lot of research and narrow it down to that, I'm pretty sure. Just can find it or anybody who can tell me where it is.
Expert:  Reggie Whiddon replied 1 year ago.

I do not know of a courtesy light timer module. The dome lamps in your csr are controlled by what is called a Central Control Module, this module grounds a relay that turns on dome lamps and it does this using input from door and hatch switchs. The CCM is located behind thr center of your dash about 6 to 8 inches above a relay board it is mounted on a slanted angle and can be hard to see.

Customer: replied 1 year ago.
Hi, Reggie
As I stated I have done a lot of research on this problem. I found a YouTube video of a person talking about it and using a pointer to point at it, but he does not say where it is located. Also if you just Google 1992 Chevy Corvette courtesy light timer module and look at images there is a wiring diagram that shows it. It is a small electrical box with about 7or 8 wires tape to a wire harness. My problem is I can't find it, so that is what I'm looking for is some one to tell me where it is. I tried to copy the image to you but it won't let me. As you probably already know Corvette's don't have much room but a lot of wires everywhere. So what I'm look for is to see if you can tell me where this small electrical box is ? Thank,Red
Expert:  Reggie Whiddon replied 1 year ago.


Vehicle Application:

1992 Corvette 5.7

Customer Concern:Interior lights stay on and kill the battery.

Average Reported Mileage:71000

Tests/Procedures:1. Remove the interior light relay and see if they go out.

2. If so, check the inputs to the Central Control Module (CCM) from the dash switch, hatch switch and the door switches.

3. If no inputs requesting the lights on, check the wire from the relay to the CCM for a short to ground holding the relay on.

Expert:  Reggie Whiddon replied 1 year ago.

bare with me Red i am looking

Expert:  Reggie Whiddon replied 1 year ago.

Here is a wiring diagram

Expert:  Reggie Whiddon replied 1 year ago.
Expert:  Reggie Whiddon replied 1 year ago.

Red something interesting look at the diagram i sent you for courtesy lights, and then look at the location pics i sent you you will see a part labeled door ajar diode module, i dont see it in the wiring diagram, it has the right amount of wires..

I believe that is what you are looking for

Expert:  Reggie Whiddon replied 1 year ago.

Red i am about to hop on my fourwheeler and get in the woods i will check back with you later please let me know if this has helped you

Customer: replied 1 year ago.
Ok, have fun. The stuff you sent really doesn't help. I looked on google and found the wiring diagram I was taking about and took a picture of it with my smart phone and sent it to my e-mail and then tried to attaché it to your message box. But it said it was to big to sent ( it is 5.1 MB ) I can only send 5MB. I'm working now and get off Wednesday morning, so I guess when I get home I will just have to keep tearing the dash apart. Thanks,Red
Expert:  Reggie Whiddon replied 1 year ago.

Hold on before you do that, Lets talk about this, please dont allow my opinion to frustrate you, I only want to help you.

Your problem is the dome lights staying on, we differ in what we believe may be wrong with it, our other difference is this component you are looking for the courtesy light timer module. I have looked at wiring from Chevrolet, All Data and Pro Demand. I can find no picture or listing of the timer module. I agree sometimes with end year models and changeover you can easily have a car with components that are not listed for that model year. But if you have my wiring diagram, what do you say we just check a couple things, We eliminate the door switchs from the circuit by doing that if your light still stays on, ok you win and i will shut up, but if those lights go off, you sir owe me a cold beer. I feel that strongly one of those is your issue, those switchs are a mechanical moving part, that are used very often in other words they have a life expectancy, the timer and relays seldom fail if they are no shorts or problems created by add ons and such.

Expert:  Reggie Whiddon replied 1 year ago.

Voltage is applied at all times from the CTSY Fuse to Courtesy, Cargo and Spare Tire Lamps. Ground to the Lamps are provided by either the Light Switch or the Courtesy Lamp Relay. The Courtesy Lamp Relay is energized by the Central Control Module (CCM) when either the LH or RH Door is opened.

On Coupe models only, ground for the Cargo Lamps is supplied from the Diode Module. They may be turned on by either the Light Switch, Courtesy Lamp Relay or the Hatch Ajar Switch (when the Hatch is open). The Diode Module prevents all of the Courtesy Lamps from turning "ON" when the Hatch is opened, and also from lighting the "Hatch Ajar" Indicator when the Hatch is closed and the Courtesy Lamps are "ON."


Voltage is applied at all times to the Vanity Mirrors and Lighted Rearview Mirror from the Cruise Fuse. Ground is provided by G202. The Lighted Rearview Mirror also receives an Incandescent Dimming Signal (CKT 8), and voltage from the Courtesy Lamp circuit (CKT 40). The Overhead Map Light on the Lighted Rearview Mirror is turned "ON" & "OFF" by an overhead switch at the mirror.


Voltage is applied at all times to the Glove Compartment switches/bulbs from the CTSY Fuse. Voltage is applied at all times to the Cigar Lighter from the B CONV PL Fuse which also feeds the console utility plug. Ground for the Glove Compartments and Cigar Lighter is supplied from G202.

Voltage is applied at all times to the Underhood Lamps from Fusible Link G through an in-line fuse underhood. Ground is supplied from G115 (LH Lamp) and G116 (RH Lamp). The Underhood Lamp Assemblies contain built-in mercury "gravity" switches that close when the hood is open.

Expert:  Reggie Whiddon replied 1 year ago.

Red that is straight from chevrolet look at it and tell me what you think. Red dont just start dismantling the dash, that is what you got me for, good luck and get back to me

Customer: replied 1 year ago.
Thanks for the help and information. I don't know how long we can keep this line of commutation open. But as I said earlier that I'm working, I work shift work and I won't get off until Wednesday morning. When I work on my car again I will take off the door panels and unplug the door switches one at a time to see if the interior lights go off, including the rear hatch switch. From you statement in your last message if the (courtesy lamp relay) goes bad will that make the lights stay on or not come on at all ? I've have only had this car a few months, but I did drive it at night a few times and it was dark inside, then I notice one night when I was driving the lights all stayed on and that is when my problem started, also I have found even though I have taken out all of the interior blubs, if it set for a couple days with out being stated the battery is dead. Until I get a chance to check out the door switches look at this and tell what you think. Type this in to You Tube ( C4 corvette cutaway interior timer ) also on different site they stated if the timer module is bad, cutting and connecting the white and black wires together the lights would go off with out delay when the doors are shut.. I appreciate all of your help. I'm pretty good at fixing mechanical things on cars, but the electrical part is my weakness. Thanks, Red
Expert:  Reggie Whiddon replied 1 year ago.

Good morning your statement about the battery drain is even more evidence of a switch failure. When a switch fails even though you pulled out the bulb it is important to note that the switch is sending a false signall to the ccm that a door is open, this will cause the module to never go to sleep causing excessive battery drain. I look forward to hearing back from you after your test

Customer: replied 1 year ago.
Hi Reggie,
Ok, I got home from work today with high hopes that one of the door/courtesy light switches were bad. So I removed both door panels and removed both door/courtesy light switches and the rear hatch switch. With the power on I used a light tester and tested all of the plugs and had power to all. Then I used the light tester and battery to test the switches. They all had a positive reading then while applying pressure and breaking the contact the power was lost. So I believe everything is good with the courtesy light switches, so for now I'm going back to looking for the courtesy light timer module so I can test it. If you have any more suggestions I can try let me know. Thanks, Red
Expert:  Reggie Whiddon replied 1 year ago.

The door jamb switches provide a ground path to module, the best way I know to check them is to undo the connector for each one and see if your lights go out, did you do that? It doesnt take much to send that ground signal i would unplug each one

Expert:  Reggie Whiddon replied 1 year ago.

Red i think after you unplug those switches and your lights are still on, drop the courtesy module and lets go to each input from the switches and make sure the ccm is being told to turn the light on, oh and i wonder if what you are referring to as timer module would be the relay, if it sticks it would keep the lights on, it is over in the relay box but none of my componenet location tells me or shows a picture of which one you would have to go by wire colors if your box doesnt label it, you may want to check that first if you suspect a bad relay swap it out with another one see if problem goes away