I have a 2004 chrysler concorde. i got three code readings does anyone know what they are? they are p0700, p0871 and p0306

P0700 is just to alert you to the fact the transmission has fault codes.

P0871
http://bestride.com/engine-trouble-codes/P0871

P0701
http://bestride.com/engine-trouble-codes/P0701

P0961
https://www.yourmechanic.com/article/p0961-obd-ii-trouble-code-pressure-control-solenoid-a-control-circuit-range-performance-by-parker-hill

The P0700 means Transmission Control System (MIL Request)
The P0760 means Shift Solenoid "C"
The P0871 means Transmission Fluid Pressure Sensor/Switch "C" Circuit Range/Performance.
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spare transponder key

the engine light blinks when the engine has a misfire the large auto parts stores will scan it for free a code p0301 is cylinder one misfire a p0306 is cylinder number six

PO871: Trans Fluid Pressure Sensor/Switch C Range/Performance.I bet this is an external sensor that can be replaced from the outside of the trans.(I didn't work on automatics at the dealer-we had 2 specialists that repaired automatic transmissions.You can see why I prefer 3 pedals under my dash!)

Is this P0605 and P0700? If so read on.
P0605 - Control Module Fault
Possible causes- ECM/PCM Harness power supply circuit is open or shorted
- ECM/PCM Harness ground supply circuit is open or shorted
- ECM/PCM may be faulty
P0700 CHRYSLER - Transaxle Control System (TCM) Malfunction
Possible causes- Shorted or open circuit within transmission control module (TCM)
- Failure of transaxle control module
Tech notes Since the P0700 is just and informative code, check the TCM for more codes to resolve the problem

Sounds like you've got the dreaded "limp mode". In the 98-01 LH cars (Concorde, 300M, Intrepid), the problem is most commonly one of the sensors of the transmission. Other possibilities are internal mechanisms (valve body) or faulty TCM (transmission control module)/

Either way, get the codes pulled (if showing any) at autozone or a similar store, which they usually do for free. You'll probably see P0700 (General transmission fault) but if there is another code shown, it might tell you what is specifically wrong with the car. If P0700 is the only code you get, you might have to go to a dealer to get it scanned since their tools can see what the underlying codes are.

The fault code P1684 means that power to your powertrain control module (PCM) was interrupted. The most common cause of this is because of a weak battery. When the car is stated, the voltage drops low enough that it cuts power to the PCM for just a brief moment, which will set the fault. It can also be caused by a wiring issue to the PCM, or a bad connection in the battery cable. It may or may not cause issues with drivability. The fault should be thoroughly diagnosed by a qualified technician

What the P0700 code means. P0700 is set when the PCM detects a malfunction in the transmission control system. This malfunction causes the vehicle to set a Check Engine Light and trigger a failsafe mode. Once the failsafe mode is set it will remain until the fault is repaired or normal operation is detected

P0732 Gear 2 Incorrect ratio
P1782 P/ES Circuit Out Of Self Test Range
P1787 2-1 Downshift Error
P0700 Transmission Control System (MIL Request) Malfunction

Here is the deal, u have some serious transmission related faults, in order to sort this out u will need to take this to the dealer, allot of testing is required to get to the bottom of this, if I had to guess I would say the trans is going to have to be overhauled.

You need to scan the tcm. Code p0700 in the ecm just tells you there is codes in the tcm.