Chassis, generic

C0628 Variable Effort Steering Module Performance

Check engine lightUsually off
EmissionsNot relevant
Drive cycleNot required
Limp modePossible

C0628 says the unit that runs variable effort steering fails its own function checks. On GM's Magnasteer that unit was a separate module in 1996–97 and became part of the brake control module from 1998. A GM patent describes the logic: a microcomputer reads coil current from speed and lateral acceleration tables, limits the total and its rate of change and drives the coil by PWM; a Steering Solutions patent gives ±3 A full scale. Performance faults cover a driver stage that cannot reach the commanded current, a failed internal self-test or corrupt calibration. GM's Tech 2 can run a function test sweeping the coil current. No maker publishes C0628 in this sense; GM's PIP5094 list (2014 and older) carries the number with an older meaning.

Likely causes

Internal fault in the controlling module or its coil driver stage
Low or unstable supply voltage so the commanded current cannot be reached
Corrupt calibration or software after a module replacement or flash

Symptoms

  • Steering effort no longer changes with speed
  • Heavy steering when parking or light steering at highway speed
  • Steering, ABS or stability warning where the brake module hosts the function

Repair estimate

DifficultyHardWorkshop job
Parts and labour€50–1,200
Time0.5–3 h

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

Parts involved

ves module

Related codes

C0629C062AC062BC061CC061F

References: aa1car.com, patents.google.com, patents.google.com, static.nhtsa.gov.