View Full Version : Interior Lights Flashing... HELP!

04-04-04, 03:58 PM
I am new to this Corvette site but some of you may recognize me, and the following post. I have searched all the archives I can find here and I didn't see anything, so if this is redundant I apologize.

I have a 84 that has developed the problem of flashing interior lights after I run the car. It is a mechanical flashing (by that I mean the flashing is predictable in frequency and duration) of all of the interior lights that starts immediately after turning the car off. The only way I can get the flashing to stop is by disconnecting the battery.

I've heard suggestions that the problem might be related to the car alarm, but I only have the factory system and as I can best remember the last time I set it off it was the exterior lights flashing with the horn blowing. I am inclined to think it isn't a alarm malfunction, but I have been wrong once or twice in the last half hour.:)

The car has always had varying degrees of ground problems in the past but as part of the stereo install and now this subsequent flashing light thing I have been cleaning all of the grounds I can find. None of the cleaning has helped either the flashing (or my ground loop stereo noise but that is a subject for a different thread).

As additional information I have recently installed a new stereo but this problem started about a week or two after the install. That install might be related to this problem but I can't imagine it is.

If anyone has had this problem I would greatly appreciate help with a solution. Or if you've got ideas I would love to hear what you think might get me out of this problem.

:w Thanks

04-04-04, 04:53 PM
wow...I feel your pain...while I didn't have exactly the same problem, mine was intermittent interior light blinking, staying off etc, I had to replace the delay module behind the passanger side dash.
I gather your problem is constant. Is the frequency of the blinking the same as the alarm flashes?

04-05-04, 08:43 AM
I have not set the alarm off recently. As memory serves the horn sounds at a much slower pace than these lights are flashing now. I can't remember if the exterior lights flash in sync with the horn or not. If the exterior lights do flash with the horn then no the alarm lights are not the same as the interior flashing I am talking about now. If the exterior lights falsh at a different pace than the horn during an alarm situation than I can only say maybe.

04-05-04, 07:21 PM
Just to update:

I set the alarm off and none of the exterior lights flash but the horn sounds of course the interior lights were flashing the entire time since they have the habit now of flashing constantly when the car is off. :mad :mad

I have disconnected completely all things electrical associated with my stereo install and the flashing problem persists. I donít doubt that the stereo install has something to do with the problem, as I can best remember (please bear with me, this problem has caused me to enjoy an adult beverage or two) the flashing didnít start as soon as the stereo got hooked up. It actually started later on and with no clear correlation (as I remember it) to a specific action on my part.

I just find it hard to believe that in the 18, 19, 20 years these cars have been on the road someone hasnít had the same problem, or at least know of someone who did.

Iíve read through the manuals again and either I am missing it, or the answer just isnít there. Thank you all for your suggestions. I guess I am going to go start pulling fuses to try and narrow down this gremlin.

Thanks again everyone!

04-06-04, 09:29 AM
Hi Bart,

I had an odd problem with my 84 as well with the interior lights. Turned out to be the delay module in front of the passenger side pad loaf of bread thing. Oddly, this also affected the door hatch release buttons, as they are powered from the same module. Do you have normal operation of the door hatch release buttons? If they are funky as well I think your delay timer is toast.

Hi all. I'm new here and have been lurjking for a while and have gained a lot of valuable information here so far. Never thought my first post would be an answer instead of a question.

04-06-04, 06:15 PM
Hi......I don't have an answer to your problem, but I am sure someone will have an answer for you soon. Anyway I wanted to welcome you to the Corvette Action Center..Enjoy!!!!!!!:w

04-06-04, 07:03 PM
At what rate do they flash? Do they flash at the same rate as the chime? Or do they flash at a rate like the turn signals?

I am guessing that you have a relay module in the pass. side dash like the later cars. If not then ignore. But I would remove the courtesy lamp relay and see if the problem continues or not. Or, can you tell me if the relay is clicking to the rythym of the flashing lights?

04-07-04, 08:26 PM
To answer some of your questions and to update yaíll about my lights I offer the following:

First an update of what I have done, I have removed the module behind the dash removed and inspected it. For 20 years old it looks just fine, there are not damaged parts or connections, and there is no smell of burning components. Since I had it apart I cleaned the contacts on the module and connector but that did not solve the problem. I plan on getting my dadís volt/ohm meter this weekend to troubleshoot the wiring and the module.

Now to answer questions: Bugger I do have normal operation of the hatch release buttons. KOPBET, the lights flash at a rate about twice that of the turn signals/hazards. In fact the lights donít match any of the cycle patterns of any of the different oscillating chimes, flashers, or alarms. There is also no clicking from a relay. I did a full car listen and got nothing.

Now for some questions of my own: Can new modules be purchased? I will be going through my Catalogs later, but I really wonít have a chance Ďtil this weekend. What can I expect to pay? KOPBET, could you email me that icon you have <-- over there?

Thanks again guys. I really appreciate your helping me. Bugger, if this forum is like others Iím apart of youíll be helping and being helped by some good people with a lot of knowledge.

04-07-04, 09:31 PM
I'm not sure which module you R&R'ed. Was it above the knee bolster on the passenger side? I was hoping that you could find and temporarily remove the courtesy lamp relay, if such thing exists on that year car, just to see if the symptom changes or goes away so we can decide which way to go. Do you see a box nearby with relays inside? I think there are four of them on my car but it is newer than yours. Sorry, I'm not more informed on that year car.

I wouldn't buy anything module-wise until you can determine that it is bad.

Another question: I am assuming from your description of the problem that the lights go off when the car is running? Is this true? While running, can you manipulate the cargo and courtesy lights with the headlamp switch? Do the lights come on when you open the door (running)?

What icon, this? You can right click it and save to your PC.


04-07-04, 11:33 PM
Here's the schematic for the Delay Timer. Put 12v to pin A & ground pin B back to the source. Put a test light on pin C. If it acts like Tinker Bell then that's the problem. Hope this helps out a little.....

04-08-04, 08:41 AM
Hi Bart,

With the delay module removed do you have normal courtesy light operation with the headlight switch? Mine did. Though the module looked, smelled, and even tasted fine, it had taken the unfortunate journey to electron heaven.

The following links show schematics of the courtesy light circuitry for the 84:



Using the above schematics, you can supply power, ground, and a momentary ground to test the module for correct function, or if you want you can mail me your module and I can test it in my car for you.

If it is the delay timer that has failed, and from your description it sounds like it has. it will be a hard part to find, at least it was for me. I have been told it is a one year-only part. Discontinued by GM and reportedly a part that fails frequently at this age. The capacitor that controls the timing dries out and starts to leak, and/or the pass transistor that supplies ground to the lights to turn them on fails.

None of the catalog houses that I know of were able to supply this module. After a dozen calls to salvage yards around the country I finally found one at Dino's Corvette Salvage for $80. After replacing the module my courtesy lights work fine now.


Good luck

04-09-04, 12:57 PM
Hey Guys,

Thanks for the schematics, I've always had toruble reading those things, but with the commentary here I think I am getting the hang of it.

Bugger, I am going to try and test it myself after I get the tools I'll need this weekend. Gotta love the 84 and all of it's one year parts, huh? I was going to try the test to see if the lights still work via the headlight switch, but I have not had the time... Tonight I will though.

I am wondering if it is something that can not only be identified but repaired. It looked like all of the electronic parts are stuff that could be found at Radio Shack. I'm not real swift with a soldering iron but that doesn't mean I wouldn't try. If the part is already broke, I can't make it more broke.

Thanks everyone, I'll update when I know something. <-- That could be a while.