Network, generic

U0304 Software Incompatibility With Gear Shift Control Module

Check engine lightUsually off
EmissionsNot relevant
Drive cycleNot required
Limp modePossible

U0304 is stored when a control unit, usually the transmission controller, finds that the software or calibration identity of the gear shift control module does not match what it expects. GM's generic U03xx procedure (Saab 9-5, 2011) treats such codes as configuration faults: checked at 9-16 V with normal bus traffic, no circuit test, cured by setup or programming. Allison uses U0304 for its 6th-generation controls as Gear Shift Module 1 Incompatible: a 6th-generation push-button selector does not work with a 5th-generation TCM, and the selector must match the TCM calibration; U0333 covers selector 2. U0103 means lost contact, U0404 invalid data from the same module. The driver may be unable to select a range.

Likely causes

Shift selector generation or type does not match the TCM calibration (e.g. after replacement)
Shift module or TCM replaced or flashed without setup
Software update aborted, wrong file loaded

Symptoms

  • Gear ranges cannot be selected or the selector does not respond
  • Transmission warning or code shown on the selector display
  • Code appears right after a selector or TCM was replaced

Repair estimate

DifficultyShop_onlyWorkshop job
Parts and labour€80–600
Time0.5–2 h

Typical range across vehicles; the real cost depends on what the testing finds.

Parts involved

gear shift moduletransmission control modulecontrol module software

Related codes

U0103U0404U0302U0300

References: saabwisonline.com, static.nhtsa.gov.