Network, generic

U0259 Lost Communication With Special Purpose Vehicle Control Module A

Check engine lightUsually off
EmissionsNot relevant
Drive cycleNot required
Limp modeNo

A special purpose vehicle control module is extra electronics for converted vehicles such as police cars, ambulances or work trucks. GM sells one from 2024 as Universal Vehicle Module (option KGU) and calls it special purpose vehicle control module for Silverado and Sierra pickups and the Tahoe and Blazer EV police vehicles. It reads switches and serial data, drives configurable outputs, offers a subset of J1939 data to upfitter equipment, and retrofitting it requires BCM and ELM reprogramming (PIT6315, Upfitter bulletin 203-b). Deutz's EMR engine controller for off-highway machines lists U0259-00 as a timeout of its tractor-trailer bridge. When slot A stops sending, the conversion functions it controls drop out, while the base vehicle normally drives on. Slots B to D are U025A to U025C, invalid data U055A.

Likely causes

Add-on controller without power or ground from the body builder's circuits
Damaged or wrongly spliced bus wiring from the conversion
Retrofit without the required vehicle configuration and module programming
Internal failure of the special purpose controller

Symptoms

  • Light bar, siren or other conversion functions inoperative or stuck
  • Upfitter switches or configurable inputs without effect

Repair estimate

DifficultyMediumWorkshop job
Parts and labour€50–700
Time0.5–3 h

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

Parts involved

special purpose vehicle module avehicle bus wiring

Related codes

U055AU025AU025BU025C

References: static.nhtsa.gov, gmupfitter.com, serdia.deutz.com.