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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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What is the age and condition of the battery. Chryslers do not tolerate low voltage conditions well and will exhibit random and weird behavior. I would suggest having the battery and charging system checked out. Be certain the engine is fully warmed up as it may be related to a warm/hot engine compartment (heat related). Personally, I suspect the alternator is beginning to fail (diode pack) allowing an ac (alternating current) ripple sufficient enough to reset the instrument cluster and cause it to go through the start-up lamp check.

Daughter's 2006 Charger was doing this a couple of times per week and as you noted, the vehicle was running fine. While investigating also noticed all of the OBD emission monitors were not ready and all stayed not ready for the week I was checking things out. I would have expected some of them would go ready after a day or so. Battery was less than 2 years old so ruled that out at the time. While watching the system voltage with the engine running, notice an ever so slight dip in the voltage. Since I had previous experience with an ac ripple on another car where the ripple affected the output speed sensor and caused the speedometer to bounce to 15-20 mph while stopped, on a hunch, I replaced the alternator. The instrument cluster show stopped and have not had an issue since. Within a day or so after the alternator replacement all of the emission monitors showed ready.
 

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The battery & charging systems can be tested for free at most auto parts stores (if the parts counter isn't too busy).
It sounds like the PCI bus is dropping out? This can be from loose and/or corroded connections.

The next time the gauges drop out, try a fist thump on the dash top above the instrument cluster. If it is an intermittent poor connection, the gauges should spring back and the warning lights go back out.

A good visual inspection may be helpful. Has there been any wet carpet or water leak issues in the interior?

As with all intermittent electrical, it taks patience to wait for it to act up. The only diagnosis that can be done is when it is acting up. Otherwise everything will act normally and there wil be nothing to fix.

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An example of a PCI bus network between the modules. The bus passes data between the modules. If the instrument cluster (MIC) loses communication, it will have the symptoms that you describe:
 

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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. . . .
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.

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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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I would look the cluster circuit board over for any damage, corrosion or cracked solder joints.
Reflow any suspect joints (see image).
If nothing is found, look for a salvage yard instrument cluster.
The odometer mileage is stored in the BCM, so your original mileage should show unchanged.

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. . . . 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. . . .
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.
 

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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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