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2007 Dodge Ram 1500 security light mystery

Battery failed, dead cell. Truck would not start. Computer stored a low voltage code and the security light, red LED on dash, came on. Replaced battery and cleared the code but the security light is flashing continuously while the truck is running. Truck does not have a security system, does not have a fob and does not have transponder keys. Have both the window sticker and factory build sheet from Dodge and no mention of any of the three above items. No codes are stored in the PCM. Dealer does not know why light flashes or how to stop it. Truck has 3.7L V6 with automatic transmission and 75000 miles. Have tried every suggestion I have heard and found to no avail. Any suggestions? Can PCM code be flashed by someone other than the dealer?

Try disconnecting the battery again. Leave it disconnected overnight. That will re-boot all the computers in the car. Might work.

Since you own a Chrysler vehicle, you must of heard of the TIPM?

Tester

Disconnected the battery terminals for 24 hours and charged the battery during that time. Reconnected battery terminals and cranked truck. Security light stayed on constantly while truck was running. After restarting the security light now blinks constantly, as before. There is no noticeable performance issues with the truck and all gages and accessories function normally. Does the firmware have to be reinstalled or an adjustment made every time there is an issue with the battery? That seems to be rather unusual for any vehicle.

Check your owner’s manual. It’s possible the security indicator is supposed to flash whenever it is armed. Another idea, there’s a computer-data-bus (CAN - bus) in your car that allows for computer-to-computer communication between the various modules. If that bus stops working for some reason the security indicator may turn on. To diagnose, your shop would use a scan tool would to probe the CAN bus functions to make sure they are all working. Even a single transistor failure could caused the CAN bus to not work correctly. Did you jump start another car, or receive a jump start yourself just prior to this problem? As mentioned above the TIPM is a common cause of weird problems. If all else fails ask your shop to temporarily replace it, might work.

Potentially related tsb’s

08-007-08 : Anti-theft system (related to failed circuit)
08-040-06: Anti-theft system (related to opening the hood)
08-016-06 : Intermittent electrical system failures (related to Ignition off draw fuse)

The security light staying on is usually a malfunction in the cluster. I have replaced a few clusters that had inoperative gauges and the security light on.

Your keys have black handles and not grey?