Chassis, generic

C0595 Brake Booster Internal Power Driver Range/Performance

Check engine lightOn
EmissionsNot relevant
Drive cycleNot required
Limp modePossible

C0595 covers the power path inside the booster electronics: master switch, safety relay and the six-transistor bridge driver. GM's 2016/2019 hybrid booster switches its master switch on, off and on again at start-up and expects the voltage ratio behind it above 0.88. In GM's IBC unit the feedback behind the motor safety relay must stay above or below 80 % of supply for 50 ms, besides configuration and SPI checks of the bridge driver; XT4 and the 2023/2025 tables test the bridge driver chip at start-up. All Type A with MIL. GM bulletin 20-NA-073 (2019–20 CT6, XT5, XT6, Blazer, Acadia, Silverado, Sierra) lists C0595 with lost assist and push-through braking, fixed by BSCM software; 19-NA-202 does the same for the 2016–19 Malibu. Mitsubishi maps C18ED-04 here.

Likely causes

Brake module software (GM 20-NA-073, 19-NA-202)
Defective bridge driver chip or its SPI communication
Motor safety relay or master switch not switching correctly
Supply voltage dips or poor module ground

Symptoms

  • Loss of brake assist, longer and softer pedal with more force needed
  • Service StabiliTrak or brake messages, traction lamp on
  • Check engine lamp (requested by the brake module)

Repair estimate

DifficultyShop_onlyWorkshop job
Parts and labour€100–3,000
Time0.5–4 h

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

Parts involved

booster internal driverbrake system control module

Related codes

C0590C0596C0582C05D2P25A2

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