Lights cycling on/off when car unattended - 07 Grand Marquis

[mr-shine]

Hi - I am a new member, and have a problem I'm hoping someone can assist me with.
Three days ago I noticed my headlights, taillights, and interior lights were on,
shortly after I had parked the car and locked it with the remote.
I unlocked/locked, lights went out - a little while later, lights on again for several minutes, then went off by themselves.
In the interest of not draining the battery overnight, I switched the headlight switch from automatic, to OFF.
The situation continued (and still is) with only the interior lights going on/off.
When the lights are on, the keypad on driver door flashes - no pattern that I can see after watching it for quite a while in my garage,
but some times it will flash as many as 50-100 times before the lights go out again.
I am scheduled to leave to drive from NY to FL tomorrow or Friday,
and don't feel safe making this trip this way - lights on/off in motel parking lot, yields call in the middle of the night, etc.,.
I ordered a new "Lighting Control Module" hoping that is what it is.
It is due in this morning, and I have a very competent mechanic who will
try to troubleshoot the problem first, but is prepared to install the module.
Does anyone have any other suggestions as to what could be causing this ?
Thank you very much - Rich

[fastblackmerc]

Sounds like the LCM.

Try tapping the LCM (3 connector black box just to the right of the steering column). If that fixes the problem then you'll need a new or repaired LCM.

Two things... there is a Ford recall on the LCMs, and I can fix your old LCM complete with a life-of-the-vehicle warranty for much less than a new one.

Oh... BTW... the new LCM will eventually have the same problem.

[Spectragod]

His car is a 07', the lcm is revised and is different than the 03'-05' models. I have had some weird problems with the 06'-11' lcm's on fleet cars. The newer lcm's have some programmability to them as well.

[RF Overlord]

Most likely the LCM is bad, but bring a 5/16" wrench with you in case the problem comes back on your trip...you can disconnect the battery overnight.

Does the problem occur only when it's dark out or in a dark place like a garage?

[fastblackmerc]

His car is a 07', the lcm is revised and is different than the 03'-05' models. I have had some weird problems with the 06'-11' lcm's on fleet cars. The newer lcm's have some programmability to them as well.

I missed that...

I've seen alot of problems with the newer LCMs.

OP - what was the last work done?

Could be the auto sensor in the dash.

[larryo340]

"I switched the headlight switch from automatic, to OFF.
The situation continued (and still is) with only the interior lights going on/off."

I've seen bad keyless entry pads do that, you also said the backlighting on the keypad flashes...could have water intrusion in the keypad...that's fairly common. I would open the door panel and unplug the keypad and see if the symptoms continue.

[mr-shine]

Thank you everyone for your input/suggestions.
I went to a mechanic my son helps sometimes at night,
who diagnosed the problem using wiring schematic,
and his scanner. He found a couple of codes - two pointing to the LCM,
two pointing to the keypad. He was almost ready to install the new LCM
I had purchased where I used to work, but decided to dig a little deeper
into the keypad. He discovered that the 9/0 key was stuck ON,
causing the lights to go on with doors closed, cycle off after a while,
then back on, etc.,. My code does not use that key, but I think I may have
used it Sat night when I was trying to remember what key would pop the trunk,
instead of using the remote, or opening the door and using that button.
When he pushed the keys one by one, his scanner showed each key action,
and then OFF. The 9/0 did not show OFF. He played with that key until
it also showed OFF - problem gone.
A very strange problem - thank goodness I went to someone who finds
electrical problems a challenge, and uses his brain, instead of just
throwing parts at it...
This was quite stressful, because I am leaving Friday morning to
drive to FL for a short vacation.
Thank you again for your input.

[Turbov6Bryan]

3-4 button unlocks all 4
5-6 button does the trunk
Combine 7-8 & 9-0 to lock

Easiest way to remember is 4 is for all 4 and 5 is the 5th :)

Glad your guy fixed the key pad, I'll have to remember this issue for later days

Awesome fix!

[RF Overlord]

Sounds like your mechanic is a keeper!

[Gerry24]

Sweet :beer: