What is the function of the manu & power buttons?

Power Door Lock Operation
The vehicle is equipped with power door locks. Each lock actuator is powered and controlled by the door module mounted in the individual door, but the rear integration module (RIM), which is the master control for the door lock system, determines when the lock functions are permitted. The RIM receives and examines the requested lock function from the individual door modules, or from the remote function actuator (RFA) via the class 2 serial data circuit. The RIM also examines the transmission shift selector position and the ignition switch position information available over the Class 2 serial data circuits. If the RIM determines that a lock or unlock function is permitted, it sends a class 2 message back to the individual door modules commanding them to perform that Lock or Unlock function.
Power Door Lock Components
The power door lock system consists of the following components:
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Driver door lock switch

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Passenger front door lock switch

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LH rear door lock switch

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RH rear door lock switch

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LH middle door lock switch (w/ V4U)

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RH middle door lock switch (w/ V4U)

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Driver door switch assembly (DDSA)

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Driver door module (DDM)

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Passenger front door module (PDM)

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LH rear door module (LRDM)

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RH rear door module (RRDM)

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Left middle door module (LMDM) (w/ V4U)

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Right middle door module (RMDM) (w/ V4U)

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Driver door lock actuator

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Passenger front door lock actuator

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LH rear door lock actuator

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RH rear door lock actuator

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LH middle door lock actuator (w/V4U)

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RH middle door lock actuator (w/ V4U)

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Driver door cylinder unlock switch

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Rear integration module (RIM)

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DRVMDL fuse (10-amp)

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PASS MDL fuse (10-amp)

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RRDR MDL fuse (10-amp)

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Class 2 serial data link

these are to raise or lower the transmission shift arm to either get more Power from your engine or use the Manu to lower in order to get more economy from your engine.

do you mean the gear lever ? i expect its to change gear ratios for different driving conditions , do you have the owners hand book as this will fully explain the function

You apparently picked up power for the amp from the same circuit as the door locks. Simply relocate the power for the amp to another circuit. There should be some taps available that can provide enough power for the switching portion, but do not try to pick up primary power from the fuse panel...run it directly to the battery...if you drill through the firewall be sure to install a grommet so that the line doesn't rub against the metal and short it out. Good luck!

A electronic control module . passenger door module . I would check for a broke wire inside the flex boot from the body to passenger door .
Watch this video .
Dodge Grand Caravan No Power Window No Power Locks CAN Trouble

check the fuse.if its not that see if the motor to the door is getting power.this will take removing the trim from the door.

The PWR button (power) is like a sports mode. It keeps in lower gears for longer so you can gain more speed. Handy for overtaking or fast lane changing. Not wise to use this all the time due to poor fuel economy.

The MANU button (manual) allows you to operate the gears manually. With MANU on and gear lever in L, it will drive in 1st. Gear lever in 2, it will drive in 2nd. Gear lever in D, it will drive in 3rd. If Overdrive is enabled then D will give you 4th gear instead.

Maybe check for a child-safety function that disables the door panel buttons.

heated seats are controlled by a relay only and the power seats are hooked to a relay and a circuit breaker. The breaker is attached inside the fuse block as well with a metal top stamped 20 or 30 amp

There are 2 fuses that powers the radio, cigar lighter, etc.
They are: the 10 amp "GAUGE" and the 15 amp "CIG".
Look under the dash, on the driver side. The "CIG" fuse is the one that you need to replace.
It is in the middle of the fusebox, bottom row. again, a 15 amp fuse.
Please advise if you need additional information.

Hope this helps, and Thanks for choosing FixYa.