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Service bulletin 21-027-15 REV-B

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.

The communication, as NHTSA indexes it (as of 2026-10-19)
TypeService bulletin
NHTSA id10148972
Published by NHTSA2018-11-26
Manufacturer's number21-027-15 REV-B
Manufacturer's date2015-08-15
NHTSA componentPOWER TRAIN

NHTSA's summary

Flash: Transmission Shift Enhancements This bulletin involves reprogramming of the Transmission Control Module (TCM) with the latest available software. A small number of customers may experience an erroneous Malfunction Indicator Lamp (MIL) Illumination. Upon further investigation, the technician may find a Diagnostic Trouble Code (DTC) stored in the TCM memory. In addition, the following TCM calibration improvements are also available for vehicles equipped with the 845RE 8 speed transmission (Sales Code DFL). These improvements are listed per engine application. 3.0L Gas Engine (Sales Code EHD) ? P1DCD - TCM monitoring processor performance multiple clutches locked up. ? P1B13 - Park-By-Wire unintended out of park position. ? P0734 - Gear 4 Shift Incorrect Ratio. ? Improved upshift timing. ? Improved torque converter engagement. ? Improved shift timing during tow mode operation. ? Improved shift points during aggressive driving. ? Calibration improvement to correct bump feel during 2-1 downshift. ? Improved shift timing while in snow, base, and hill modes. 3.6L Gas Engine (Sales Code ERB) ? P1DCD - TCM monitoring processor performance multiple clutches locked up. ? P1B13 - Park-By-Wire unintended out of park position. ? P0734 - Gear 4 Shift Incorrect Ratio. ? Improved 4-3 and 3-2 downshifts. ? Improved shift timing at higher altitudes. ? Improved shift timing while in sand mode. ? Calibration improvement for multi-gear downshift timing during passing maneuvers. ? Calibration improvement for intermittent delayed upshift.

The document

The document is the manufacturer's. This site does not hold it. NHTSA files a document at one of these two addresses; we have not asked NHTSA which.

Components

Transmission and driveline

Trouble codes named

P0734, P1B13, P1DCD

Vehicles listed
DODGE DURANGO2015
JEEP GRAND CHEROKEE2015

Listing a model year does not mean every vehicle of it is concerned: the document says which.

Recalls for the same vehicles and component
20161842016-04-26. Powertrain
16V2400002016-04-25. POWER TRAIN:AUTOMATIC TRANSMISSION:CONTROL MODULE (TCM/PCM/TECM)

A recall listed here may apply to some of the same vehicles. Only the manufacturer can say whether it applies to one vehicle.

Other bulletins for the same vehicles and component
S26230000232026-04-15. Service bulletin. Power Liftgate Inoperative.
S2621000003 REV.A2026-03-18. Service bulletin. The vehicle will exhibit a service transmission/check engine warning indicator for the following transmission models: 845RE, 8HP45, 850RE, 8HP50, 8HP70, 8HP75, 8HP75-PHEV, 8HP75-LCV, 8HP90, 8HP95. Transmissions may exhibit the following diagnostic codes: P07E4, P1DB2, P0716, P1B14, P0733, P1D90, P1DB7, P1B13.
1012322024-11-07. Service bulletin. Plate - Planetary
21040142023-02-21. Service bulletin. 8HP70 Transmission Shift Enhancements
21039142023-02-21. Service bulletin. Transmission Shift Enhancements
21038142023-02-21. Service bulletin. 8HP70 SRT Transmission Shift Enhancements
18067142023-02-21. Service bulletin. MIL Illumination, P1CF3 Battery Temperature Sensor Out of Range Low
18063142023-02-21. Service bulletin. 5.7L Powertrain Diagnostic And System Improvements
21030142023-01-17. Service bulletin. Transmission Quick Learn Procedure
18074142023-01-17. Service bulletin. Flash: 3.0L Powertrain Diagnostic And System Enhancements This bulletin involves reprogramming the Powertrain Control Module (PCM) with the latest available software. The following software is being released to improve A/C compressor relay duty cycle operation to prevent ignition off battery draw.