Network, generic

U0128 Lost Communication With Park Brake Control Module

Check engine lightOn
EmissionsNot relevant
Drive cycleNot required
Limp modeNo

U0128 signals that the electric parking brake controller has dropped off the bus. GM rates it very differently by node: the 2017 engine table waits 10 s for the park brake message and treats a miss as Type A (MIL at once), while the 2019 chassis controller (ICCM) needs only 1 s but files it as Type C without MIL; from model year 2018 GM folds this ICCM check into U0121. Saab's 9-5 list adds subtypes 71, 72 and 74 for corrupt frames. FCA names U0128 among the codes of a 2019 Cherokee 3.2 L PCM update. In GM Silverado trucks it appears with many other U codes when a harness fault upsets the whole network (PIT5713A). U0135/U0136 cover further park brake modules. The parking brake may not apply or release.

Likely causes

Fuse, supply or ground of the park brake module missing
Chafed or corroded bus wiring, often affecting several modules at once
Weak battery causing the module to drop out (stored code)
Controller software issue fixed by reprogramming
Park brake control module internally faulty

Symptoms

  • Service Parking Brake message or brake warning lamp
  • Electric parking brake does not apply or release
  • MIL on in vehicles where the engine controller stores it

Repair estimate

DifficultyMediumWorkshop job
Parts and labour€60–1,200
Time0.5–4 h

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

Parts involved

parking brake modulecan bus wiring

Related codes

U0317U0438U0135U0136U0129

References: gsi.ext.gm.com, gsi.ext.gm.com, saabwisonline.com, static.nhtsa.gov.