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Service bulletins for the 2020 Cadillac CT4

A bulletin is a manufacturer's communication to its dealers, as NHTSA indexes it. The summary is NHTSA's. The document is the manufacturer's: read it at NHTSA. A bulletin is not a recall, and listing a model year does not mean every vehicle of it is concerned.

888 on file from NHTSA, as of 2026-10-19.

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Only bulletins with component: Electrical system are shown. Show all

Bulletins, newest first
21NA0602021-05-10. Service bulletin. ELECTRICAL SYSTEM. This service bulletin describes the TLC/SPS2 Module Programming Requirements for Vehicles Using GM?s New Vehicle Intelligence Platform (VIP) Module Architecture.
20NA1322021-05-03. Service bulletin. ELECTRICAL SYSTEM. This warranty administration bulletin provides policy information on the requirements for battery testing and warranty replacements.
20NA1232021-05-03. Service bulletin. ELECTRICAL SYSTEM. This service bulletin provides repair information to correct a customer concern of a Malfunction Indicator Lamp (MIL) Illuminated with DTCs U1961, U1983 setting.
PIT5817A2021-04-19. Service bulletin. ELECTRICAL SYSTEM. This Preliminary information communicates and issue with a SES MIL and the BCM keeping the ignition main relay on after the vehicle is turned off. Dealers are to replace the BCM.
PIC6384D2021-04-19. Service bulletin. ELECTRICAL SYSTEM; STRUCTURE. This Preliminary information communicates a parts restriction is in place for the Body Control Module on 2020 Cadillac CT4, CT5, Chevrolet Corvette, Suburban, Tahoe and GMC Yukon.
PIE0606A2021-03-08. Service bulletin. AIR BAGS; ELECTRICAL SYSTEM. This engineering information (EI) is requesting information from technicians to perform the check list provided and contact the engineer listed in regards to the service airbag lamp illuminated on the driver information center (DIC).
030846004X2021-03-08. Service bulletin. ELECTRICAL SYSTEM; EQUIPMENT:OTHER:OWNERS/SERVICE/OTHER MANUAL. This service bulletin announces that the Part Restriction and Ordering Process Information for OnStar® Vehicle Communication Interface Modules (VCIM) (GMNA Only) has ended.
PIE06062021-03-01. Service bulletin. ELECTRICAL SYSTEM; AIR BAGS. This engineering information (EI) is requesting information from technicians to perform the check list provided and contact the engineer listed in regards to the service airbag lamp illuminated on the driver information center (DIC).
N2023205102021-03-01. Service bulletin. AIR BAGS; ENGINE AND ENGINE COOLING; ELECTRICAL SYSTEM; FUEL SYSTEM, GASOLINE; EQUIPMENT. Customer Satisfaction Program. Certain vehicles, equipped with a gas engine, may have a condition in which the printed circuit board inside of the water pump may have been manufactured incorrectly potentially causing a water pump failure. The vehicle coolant system temperature is monitored and will display multiple warnings to the customer as coolant temperatures rise. At a set coolant temperature, the MIL will illuminate, DTC P2B85 will set in the engine control module (ECM), the oil pressure gauge will indicate high oil pressure and reduced torque with notification to the driver of reduced power will occur. If the customer continues to drive after this warning and the coolant temperature continues to rise, a chime will occur, the AC will be disabled and an additional message instructing the driver to idle will illuminate. If the customer continues to drive the vehicle after all previous warnings and the coolant temperature continues to rise a message the engine will shut down could occur, and the engine will be shut down. Dealers are to replace the water pump.
N2023205102021-02-16. Service bulletin. LANE DEPARTURE; FUEL SYSTEM, GASOLINE; SERVICE BRAKES, HYDRAULIC; ELECTRICAL SYSTEM; AIR BAGS; ENGINE AND ENGINE COOLING; POWER TRAIN. Customer Satisfaction Program. Certain vehicles, equipped with a gas engine, may have a condition in which the printed circuit board inside of the water pump may have been manufactured incorrectly potentially causing a water pump failure. The vehicle coolant system temperature is monitored and will display multiple warnings to the customer as coolant temperatures rise. At a set coolant temperature, the MIL will illuminate, DTC P2B85 will set in the engine control module (ECM), the oil pressure gauge will indicate high oil pressure and reduced torque with notification to the driver of reduced power will occur. If the customer continues to drive after this warning and the coolant temperature continues to rise, a chime will occur, the AC will be disabled and an additional message instructing the driver to idle will illuminate. If the customer continues to drive the vehicle after all previous warnings and the coolant temperature continues to rise a message the engine will shut down could occur, and the engine will be shut down. Dealers are to replace the water pump.
PIC6385B2021-02-16. Service bulletin. EXTERIOR LIGHTING; ELECTRICAL SYSTEM. This Preliminary information communicates a parts restriction is in place for the exterior lighting module on 2020 Cadillac CT4, CT5 and Chevrolet Corvette.
PIE06062021-02-01. Service bulletin. AIR BAGS; ELECTRICAL SYSTEM. This engineering information (EI) is requesting information from technicians to perform the check list provided and contact the engineer listed in regards to the service airbag lamp illuminated on the driver information center (DIC).
20NA1142021-02-01. Service bulletin. EQUIPMENT; ELECTRICAL SYSTEM. This informational bulletin provides information for dealers/technicians on the false setting of DTC U0212.
16NA0192021-02-01. Service bulletin. POWER TRAIN; ELECTRICAL SYSTEM:SOFTWARE. This informational bulletin provides information on Transmission Adaptive Functions and Correcting Low Mileage Harsh Shifts, Slips, or Flares.
PIC6385B2021-01-25. Service bulletin. ELECTRICAL SYSTEM; EXTERIOR LIGHTING. This Preliminary information communicates a parts restriction is in place for the exterior lighting module on 2020 Cadillac CT4, CT5 and Chevrolet Corvette.
20NA1232020-12-21. Service bulletin. EQUIPMENT ADAPTIVE/MOBILITY; ELECTRICAL SYSTEM; EQUIPMENT. This service bulletin provides repair information to correct a customer concern of a Malfunction Indicator Lamp (MIL) Illuminated with DTCs U1961, U1983 setting.
PIT5782A2020-12-14. Service bulletin. ELECTRICAL SYSTEM; EQUIPMENT. This Preliminary information communicates and issue with programming a replacement side object detection module and engineering is working on the issue.
1308116001F2020-12-07. Service bulletin. EQUIPMENT; ELECTRICAL SYSTEM; POWER TRAIN:AUTOMATIC TRANSMISSION. The intent of this technical bulletin is to identify aftermarket ALDL or DLC interface devices as potential sources for causing multiple customer concerns that do not have other diagnostic methods to identify them.
N2023083202020-11-30. Service bulletin. ELECTRICAL SYSTEM:12V/24V/48V BATTERY; EQUIPMENT:ELECTRICAL:RADIO/TAPE DECK/CD ETC.. Customer Satisfaction Program - Certain 2020 model year Cadillac CT4, CT5, and Chevrolet Corvette vehicles, equipped with the Cadillac User Experience with embedded navigation or the Infotainment 3 premium system w/navigation (RPO IOT), may have a condition where the radio display is non-functional except for the backup camera. The embedded Multi-Media Controller (eMMC) firmware contains a defect that could cause a continuous rebooting condition. Rebooting will continue even after shutdown, resulting in a battery drain for the affected vehicle, and possibly a dead battery and a no-start condition. Dealers will replace the radio receiver.
20NA1962020-11-30. Service bulletin. ELECTRICAL SYSTEM. This service bulletin provides information and a service procedure for dealers/technicians on OnStar Over the Air Update for TTY / TDD Operation and Continuous Improvement Changes.
PIC6391D2020-11-16. Service bulletin. SERVICE BRAKES, HYDRAULIC; ELECTRICAL SYSTEM. This PI communicates a parts restriction is in effect on 2020 Cadillac CT4, CT5 and Chevrolet Corvette Electronic Brake Boost Control Module and Valve Kit, Brake Pressure Modulator.
PIP5675G2020-11-16. Service bulletin. ELECTRICAL SYSTEM. This Preliminary information communicates to the dealer that a customer may comment that the MIL light is illuminated. The technician may find P1098 and/or P26BB set current or history. That this may be caused by a software anomaly, and that GM is currently looking into the issue. It provides testing and related direction based on the results.
PIC6390B2020-11-16. Service bulletin. ELECTRICAL SYSTEM. This Preliminary information communicates a parts restriction is in place for the Central Gateway Module on 2020 Cadillac CT4, CT5, and Chevrolet Corvette.
PIP5675F2020-11-16. Service bulletin. ELECTRICAL SYSTEM. This Preliminary information communicates to the dealer that a customer may comment that the MIL light is illuminated. The technician may find P1098 and/or P26BB set current or history. That this may be caused by a software anomaly, and that GM is currently looking into the issue. It provides testing and related direction based on the results.
20NA1912020-10-26. Service bulletin. ELECTRICAL SYSTEM; ENGINE AND ENGINE COOLING. This technical bulletin provides repair information to correct a customer concern of Auto Start/Stop Disabled with Malfunction Indicator Lamp (MIL) Illuminated and DTC U0599 set.

The summaries are NHTSA's. Each bulletin's page links NHTSA's copy of the manufacturer's document.