I have a mint condition 1994-c4 with only 26k miles. I replaced all the interior lights, including the under hood lites, with LED's. I love the bright white illumination.
I replaced the battery just prior. Key fob (PKE) has been erratic since, the security system has acted up very intermittently and the interior lights come on for no good reason & sometimes don't time out for a prolonged period. The security system went into alarm mode twice in the past 3 weeks, both times the car was totally not disturbed or touched.
Is there another means to reset the computer, besides unhooking the battery and waiting the prescribed time? ..... which I have done.
Could the LED lights be causing a problem???
____________________________________
Thanks for the quick response. I agree the LED lights most likely are not the cause.
The car had another security alert (horn honking etc) at midnight again. I have removed the horn fuse, to keep peace with the neighbors ..... until I get this resolved.
__________ Some additional information ____________
The battery is drained occasionally, since this problem surfaced. (New battery) I have fully charged it and monitor voltage with a meter frequently. This has not happened the last 48 hours after turning the PKE off.
The interior lights are erratic, sometimes turn on when doors are unlooked with key & door opened, but not always. Same thing with the lights shutting off. Occasionally turn on for a prolonged period of time but eventually turn off.
While driving the door locks chatter, appears to be related to hitting a bump in the road, (apparently vibration related). I have tried pounding on the doors, with my hand, attempting to recreate the lock chattering. So far I have not been able to localize the source.
I determined that there is a fuse labeled "PKE". Am considering pulling this fuse in order to isolate this problem, Will this completely disable the security & passive key entry system??
New information____________________
Thank you for your input. Very helpful.
Present state of car is:
1. There is a PKE fuse, Installed - I have never unplugged it.
2. Passive key system is turned OFF
3. LED's are installed - (2) under hood, (2)under mirror, (2) floor well, (2) door panel, (2) luggage area & (1) license plate.
4. I have removed the Horn fuse to eliminate the unwanted HONKING while working this problem.

I did try your suggestions, sitting in car with ignition switch on and moving tumbler around: no unustal symptoms. This AM the interior lights were on while car was totally undisturbed. I noticed that the "security" light also comes on with the interior lights. Turning the ignition key on/off did reset this condition. I sat in car and made a meaningful discovery concerning this problem and related to the passenger door.
Light finger pressure ​​when applied to the inside​​​​ passenger door panel, causes the interior & security​ light s to come on....... and a sharp rap with palm of hand even caused the doors to unlock. The most sensitive area is at the rear of this door (latch area).
This is the most hopeful discovery I have made concerning this problem.
I plan to remove the passenger door panel to further investigate and will post the results. (maybe a day or two before I get the time)
**********************
PROBLEM SOLVED: Right ON with the door ajar switch. THIS WAS THE PROBLEM.
Not related to the installation of interior lighting LEDs. It was just a coincidence that the problem surfaced following the LED install.
Evidently the door ajar switch located in the passenger door was failing + the outside temperature, at night (even here in Phoenix), got down into the lower 40's.
The failing switch was found to be very erratic internal contact make-break properties and the cold aggravated this condition. It was sensitive to vibrations as well.
I will order a new switch. Temporarally I placed a self adhesive rubber bumper pad in position to further depress the plunger, when door is closed.
Normal operation has been proven to be: with a door open, lock switch operated (doors locked), push in door ajar switch plunger - both door locks will move to the unlocked position or chatter if unlocked.(This is the case if key is in ignition either in the Off or ON position)
If no key is in ignition, the interior lights will go into timeout condition when the door jam switch is operated and doors are un-locked
***** I removed the faulty door ajar switch and connected it to an ohm meter. It is a normally closed switch (plunger out - not operated). When plunger is pushed in there is a point where the switch transfers to "open" and should continue to be "open" during the entire inward travel.
However this failing switch had momentary make/break periods during the inward travel this was especially true close to the transfer point. Occasionally it would be closed during the entire inward travel ... and if at a normally open point, I tapped on the switch housing, there would be momentary continuity.
Thnak you. The Corvette forum was a great asset which lead to this solution.
Oz
*******

 

I have a ‘96 and replaced all of the interior lights, as well as exterior with LEDs and have not experienced any difficulties. I don’t believe your problem is the lights.
Maybe, for just an easy fix, try disconnecting the negative battery terminal and see if that fixes the issue.

 

It could actually be a problem with LEDs. I have to do some measurement on my CCM but it might be possible that the courtesy lights are PWM (pulse width modulation) driven and not DC driven.

If that's the case, you need to understand that LEDs do not electrically behave like light bulbs. They sure consume much less for the same lighting capability but their driving pattern (when PWM driven) consists in very sharp square waves that tends to radiate noise.

If you have a close look at the CCM wire bundle, they are all tighlty packed together, increasing the risk of coupling noise into surrounding wires (like the PKE signalling, which is also belonging to this wire harness).

If that's the case, I would not be surprised that the PKE / UTD behaves erratically. The interfaces are filtered for noise but not the kind of noise that you have introduced with the LEDs.

I don't know if I will have the time on short notice to check how the courtesy lights are driven.

Easy test...switch back to classic light bulbs...

 

Disregard the 'testing' just put it back to 'stock' anyway!

 

I had thoughts along this same line. A question that I have however, is why would this cause a problem when all lights are off? and could I possibly install a capacitor to filter the electrical noise?
I have experience in the electronic field and appreciate any/all input & am able to experiment with potential solutions. I just wiched that I still had an oscilloscope.

Please send any other ideas

 

If the problem also happens when the lights are turned off, then it is caused by something completely different. Some questions and ideas :

1- Have you wired any other aftermarket electronics recently, in addition to the LEDs ?

2- Do you have any electronic devices operating nearby the car in the PKE radio-frequency range (i think it's 900 MHz).

3- Have you tried replacing your Keyfob battery (it normaly only affect the detection range but a low battery could lead to erratic behaviour). Also try to put your Keyfob in a metalic box far away from the car and see if the problem still happens. Normally, the keyfob sends a signal every 21s when moved (there is a motion sensor inside), if not moved even if close to the car, it should not send any signals. Also :

Some FSM information for your info if you do not know how it works :

The PKE receiver constantly scans for a
transmitter’s signal. Once it has seen that the valid
transmitter has gone out of range, it waits 5 seconds,
locks the doors, arms the universal theft deterrent
system, and also will turn “OFF” the courtesy lights
and sound the horn through the CCM. This only
occurs if the passive lock/unlock mode has been turned
“ON.”

5- Does the PKE work normally (can you lock and unlock) ?

6- There is one PKE antenna in the driver door. Could it be loose, explaining the driver door chatter ?

7- If the AJAR switch itself is damaged and shaky (chatter as you described), it could accidently trigger the alarm if the vehicule was initially locked. That's the whole concept of UTD. If the alarm goes off, it means that a door or the hatch has been opened (so the AJAR switch open) while the vehicule was locked. If the vehicule is unlocked and the lights randomly goes on, it could also be explained by a faulty AJAR switch. If it happens too frequently, the CCM will be rarely asleep and will drain your battery quick. Try to investigate the door AJAR switches and hatch if you see or feel anything abnormal. This thing : https://www.google.com/url?sa=i&url=...AAAAAdAAAAABAJ

The goal would be to clearly separate a PKE issue from a simple door issue. So put the PKE fob away to remove one variable from the problem, or pull the fuse as you did, and see if the courtesy light randomly goes on.

8- An issue with the CCM itself, which is bit more complex to investigate.

 

Just came back from a test drive. Have turned off the passive key feature. Battery has stayed up for several days now. I have not installed any electronic devices since installing the LEDs.
Everything seems to work as designed with the exception of the door lock solenoids chattering when hitting a bump. Another key clue is that, while driving, doors locked,
both doors unlock every time the car experiences a medium to sharp bump. When doors are unlocked and a vibration (bump) both door lock solenoids chatter and the interior door lock slides jump (chatter). I surmise that the door unlock switch in the passenger door/ the signal wire carrying the voltage is causing this action.
I tend to lean towards this rather than the door AJAR switch due to the observation of the information panel with NO "Door Ajar" Indication
If this is the case it could cause the alarm to activate if the doors are locked with the PKE/security system ON.
As you pointed out this could also cause the CCM not asleep and discharge the battery.
Thanks again for your information .
Oz

 

Interesting,

There's two things which are for me difficult to understand :

1 - The power door switches are motor driven according to the FSM (page "PASSIVE KEYLESS ENTRY/POWER DOOR LOCKS"). So it's not just a simple solenoid held in position by a signal that a bump could eventually change the state. The motor would normally rotate in direction to lock and in the other to unlock. That would mean that the unlock/lock signal must be applied to the to activate the motors.

2 - How would the power door switches change positions when the car is absolutely not moving. I also consider there a parasitic signal that would trigger the motor to unlock and then trigger the UTD.

Do you plan to continue investigating or are you considering leaving the PKE fuse out and do nothing about the random power switches behaviour ? That tickles my mind

 

What about a failing door switch. If that is the case it could both set the alarm off because it would think someone opened the door while armed and drain the battery (interior lights stay on). I’ve heard some try a squirt of wd40 is a free fix attempt.

 

Sit in the car, key on, engine off, shut doors, lock the doors.

Now wiggle the key back and forward in the ignition barrel.

Do the door locks do anything then?

Next step is unplug your PKE module and see what impact that has (can't remember if it is on it's own fuse on a 94 and my 94 service manuals are near the bottom of the stack of every other year)

I had LEDs all through my 94 coupe and also have them all through my 93 Callaway vert, never been an issue but i still have stock bulbs in the bottom of the mirror.

 

Thank you for your input. Very helpful.
Present state of car is:
1. There is a PKE fuse, Installed - I have never unplugged it.
2. Passive key system is turned OFF
3. LED's are installed - (2) under hood, (2)under mirror, (2) floor well, (2) door panel, (2) luggage area & (1) license plate.
4. I have removed the Horn fuse to eliminate the unwanted HONKING while working this problem.

I did try your suggestions, sitting in car with ignition switch on and moving tumbler around: no unustal symptoms. This AM the interior lights were on while car was totally undisturbed. I noticed that the "security" light also comes on with the interior lights. Turning the ignition key on/off did reset this condition. I sat in car and made a meaningful discovery concerning this problem and related to the passenger door.
Light finger pressure ​​when applied to the inside​​​​ passenger door panel, causes the interior & security​ light s to come on....... and a sharp rap with palm of hand even caused the doors to unlock. The most sensitive area is at the rear of this door (latch area).
This is the most hopeful discovery I have made concerning this problem.

 

It looks like you are manually and slightly moving the lock switch by doing this. This generates an interrupt signal to the CCM which then wakes up (and turn on the courtesy lights). See below,

The courtesy light should switch off after 5 to 15s is you remove this conditions.

Of course, if UTD/PKE is armed, this will trigger the alarm.

 

I have an 89 convertible. I replaced all the interior lights including all the lights in the dash. Much brighter and better for the instruments. No heat like the halogens, they were heat discoloring the circuit boards on the cluster.

 

this is unrelated to the question though.

 

PROBLEM SOLVED: Right ON with the door ajar switch. THIS WAS THE PROBLEM.
Not related to the installation of interior lighting LEDs. It was just a coincidence that the problem surfaced following the LED install.
Evidently the door ajar switch located in the passenger door was failing + the outside temperature, at night (even here in Phoenix), got down into the lower 40's.
The failing switch was found to be very erratic internal contact make-break properties and the cold aggravated this condition. It was sensitive to vibrations as well.
I will order a new switch. Temporarally I placed a self adhesive rubber bumper pad in position to further depress the plunger, when door is closed.
Normal operation has been proven to be: with a door open, lock switch operated (doors locked), push in door ajar switch plunger - both door locks will move to the unlocked position or chatter if unlocked.
Thnak you
Oz

 

Nice! Good job!