Cadillac P1850: Brake Band Apply Solenoid Circuit Malfunction (4L30-E)

What Does The Cadillac P1850 Code Mean?

Engine running with the TCM High Side driver closed, then with the A/T Band Control solenoid commanded “off”, the TCM detected the solenoid feedback voltage below 2.45v; or with the A/T Band Control solenoid commanded “off”, the feedback voltage was from  or the Band Control solenoid was commanded off and the feedback voltage was from 2.45 -3.53v, or the Band Control solenoid was commanded on and the feedback voltage was more than 4.02v

What Are The Potential Causes Of The Cadillac P1850 Code?

Below are some potential causes of this DTC:

• A/T band solenoid control circuit is open or shorted to ground
• A/T band control solenoid circuit is shorted to system power
• A/T band control solenoid power circuit (from PCM) is open
• A/T band control solenoid is damaged or has failed
• PCM has failed

Recommended Parts

Below are some recommended auto parts to help you address the trouble code affecting your vehicle and get it running smoothly again:

>>> WORKPRO 582-piece Crimp Terminals, Wire Connectors, Heat Shrink Tube, Electrical Repair Kit
>>> 4L60E Transmission Shift Solenoid Valve Set
>>> GM Genuine Parts 12633238 Engine Control Module

Note: During the purchasing process, please check carefully whether the part you want to buy fits your car!

Reference Sources

GM, 2013, Service Bullettin – Prior To Any Circuit Testing.