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Warning lights all on, then back off, while driving

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2007 Town and Country, about 190,000 miles.
While driving at steady highway speeds, I noticed the speedo going down toward zero. Then all the warning lights came on, and within a few seconds back off and the speedo went back to the correct reading. The engine ran smoothly. I saw no change in the voltmeter that is plugged into my lighter socket. Vehicle ran trouble-free the rest of the day.

Is this a warning sign of something that needs fix/replace? I like to do my own work and am seeking advice on what to do. I did unplug and plug back in the underhood fuse for the BCM, and saw no corrosion there.
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Discussion Starter · #5 ·
When the ignition key switch is initially turned to the ON / RUN posiiton, a wake up signal is sent to the instrument cluster. The cluster logic will power and illuminate all lamps for bulb check and then turn them off. I think you are getting an intermittent power up signal (poor connection) and the logic thinks it should do a bulb check each time as a result. So you would get flashing lamps on the instrument cluster.

There is a self test diagnostic procedure that you can perform on the instrument cluster. See attached image. This is for a 2005 minivan and I believe it would still be correct for a 2007 model? Also included is the pinout for the electrical connector at the cluster assembly. Check and make sure tight fitment of pins to receptacles and no broken solder joints on the cluster circuit board.

View attachment 89658
Thanks for the info. The self test shows code 100.6 - SBEC/DEC/MCM Communication Fault. I don't know what those mean, and where to look. The battery is about one year old, measures a bit over 12V at rest and 14.4V engine running.
 

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Discussion Starter · #8 ·
Your battery and electrical system voltages are within design parameters so I would NOT suspect the battery to be the source of this problem.

SBEC is acronym for single body engine controller or otherwise called the PCM (powertrian control module.) Acronyms DEC and MCM ????

The BCM receives the analog signal from the fuel level sensor, converts it to digital and transmits it over the PCI bus communication network. The PCM interprets engine temperature, converts to digital and transmits it over the PCI bus commuication network. You did not indicate a problem with the fuel level and engine temperature gauge readings so I am thinking this code 100.6 is a symptom but somewhat misleading to the actual problem.

I would follow the advice from ImperialCrown and check the instrument panel circuit board. Check the electrical connector at the instrument panel according to the pinout diagram in post #4.
Yes, I will take out the instrument panel and give a close look at the circuit board. I did replace some bulbs back there a couple months ago. Thanks for all the advice.
 
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