2004 Lincoln Town car brake light on, I clean code but no difference U1900

U1900 FORD - CAN Communication Bus Fault

Read more: https://www.autocodes.com/u1900_ford.html
Possible causes
Faulty / intermittent ignition switch connections
CAN Bus wiring intermittently open/shorted to power or ground Faulty / intermittent connection at PCM
Faulty electrical connections at ABS Control Module
Faulty electrical connections at the instrument cluster
Poor connections at the trailer brake controller/trailer connector

Tech notes This is typically a false/intermittent code. It can occur if: Someone hooks up a scanner to the OBDII port while the ignition is on or while the engine is idling. A trailer brake system is installed improperly/incorrectly on a truck with ABS (anti-lock brakes).

When is the code detected? When the PCM, Brake Controller and Instrument Cluster are unable to communicate with each other at any time while the ignition switch is turned to the "Run" position, code U1900 sets in memory.

Possible symptoms Engine Light ON (or Service Engine Soon Warning Light) Amber ABS (Anti-lock Brakes) Light ON Wrench Light On

U1900 Ford Description The Anti-ock Brakes System (ABS) module, the Powertrain Control Module (PCM), and the instrument cluster communicate over the Controller Area Network (CAN) Bus. This is a high-speed bus communication system and is not fault tolerant, which means any type of intermittent/loose connection between these 3 controllers will cause communication to stop. When the PCM, ABS module and instrument cluster are unable to communicate with each other at any time while the ignition switch is turned on, code U1900 will set.

Read more: https://www.autocodes.com/u1900_ford.html

U1900 CAN Communication Bus Fault Vehicle Security Module REFER to Section 418-00 . U1900 CAN Communication Bus Fault 4WD Control Module REFER to Section 418-00 . U1900 CAN Communication Bus Fault-Recieve Error Parking Aid Module REFER to Section 418-00 . U1900 CAN Communication Bus Fault-Recieve Error DSM REFER to Section 418-00 . U1900 CAN Communication Bus Fault-Recieve Error Instrument Cluster If the 4X4 light is not flashing at key ON, REFER to Section 418-00 .
If the 4X4 light is flashing at key ON, REFER to Section 308-07A . U1900 CAN Communication Bus Fault-Recieve Error Power Liftgate Module REFER to Section 418-00 . U1900 CAN Communication Bus Fault-Recieve Error Stability Assist Module REFER to Section 418-00 . U1900 CAN Communication Bus Fault-Recieve Error Air Suspension Module REFER to Section 418-00 .
which module won't communicate ? need a up scale scanner to communicate with all the modules on the vehicle. Do you know what C.A.N - controller area network is ? Serial data bus (network) All the modules on the vehicle share data on the network . U code's indicate a problem with the network .

check for bad ground open circuit

cHECK THE BRAKE LIGHT SWITCH,IT IS MOST LIKELY THE CAUSE.

If you still have brakes and it sounds like you do.
Air suspension?
But I would go for shock oil.

YOU HAVE A FAILTY RELAY AND SWITCH IN THE CAR

The code should be on a white sticker located on the truck hinge. Mine is on the right hinge.

First, disconnect the battery cable for about 10 minutes. This will clear the computer. Any codes set will be new. Check to see if all vacuum lines were connected by the tech. This code indicates EGR flow is not sufficient. Many people replace the DPFE which is a small part with 2 vacuum lines and one electric connector at the back of the motor.
However, it is just as important to clean the carbon buildup in the airhorn below a part called the throttle valve. You see the DPFE can be accurate in setting a low flow Code, but it doesn't know the difference between carbon buildup and bad parts.

brake light switch located on the steering column by brake peddal

Did the dealer clear the codes last time you were in. they have to be cleared