I recently picked up a 2006 Dodge Dakota with a 545rfe. It was in limp mode when I got it, but I got it for cheap so I figured I would try to fix it. I changed the valve body and solenoid pack, all sensors on trans, PCM/tcm, and trans relay. I have after all that I have gotten codes P0882 P0700 P0750. Previous codes included P0846 P0871 P0988 P0876 P0882.
I have checked obvious locations for loose grounds and have inspected for any obvious wiring issues. I found a disconnected ground, but reconnected it. Any help is appreciated!

 

P0882 This is the code you need to fix first. TCM power input signal low. If the TCM isn't getting proper power, nothing is going to work right, and the PCM will automatically drop it into limp mode.

 

The alternator and starter passed a bench test. Battery is new and terminals are new. I checked under the dash and found an after market alarm. It is spliced into the main harnesses under the dash very badly. Some of the wires have 3 or 4 resistors just out in the open used to fill the gap where wire would not reach. I'm pretty sure my problem lies in this wiring rats nest. I'm going to attempt to completely remove the alarm. My problem is it's so cluttered and very hard to distinguish between oem and after market wiring. Im also having a hard time finding a wiring diagram for under the dash

 

If you click this link, you can download the 2005 Factory Service Manual, which has all the wiring diagrams that you could want.

Hope it helps.

 

Thanks for the diagram! I got the wiring situated. Now I'm getting P0700 P0750. I just replaced the valve body and solenoid pack though. Can it be defective? I got it off eBay "refurbished". I'd rather not keep replacing it. If that's not the problem, what else can it be?