Powertrain, generic (extended)

P2670 Actuator Supply Voltage B Circuit Low

Check engine lightOn
EmissionsRelevant
Drive cycleNot required
Limp modePossible

P2670 is set when the second high-side actuator supply delivers too little voltage while it is switched on, which nearly always means a short to ground somewhere on the supply line or in a load connected to it. GM documents it in several controllers. In the 16OBDG08 TCM tables for Silverado and Sierra a ground short is recognised at an impedance of 0.43 ohm or less, confirmed after three events, Type A. GM's 2023 TCM compares the supply voltage with battery voltage and also watches the average current, 60 ms to fail, Type A. In GM's hybrid tables (Volt THPC in 16OBDG01, HPC1 in 19OBDG01) high side driver 2 reports the short within about 0.13 s, again Type A after one trip. Solenoids on that supply drop out, so the transmission enters a failsafe mode.

Likely causes

Supply wire chafed and shorted to ground
Shorted solenoid on the supplied group pulling the line down
Faulty high-side driver in the controller

Symptoms

  • Failsafe gear, no normal shifting
  • MIL on immediately
  • Further solenoid circuit codes stored alongside

Repair estimate

DifficultyHardWorkshop job
Parts and labour€100–1,500
Time1–5 h

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

Parts involved

actuator supply bcontrol modulewiring harness

Related codes

P2669P2671P0658P2685

References: gsi.ext.gm.com, gsi.ext.gm.com, gsi.ext.gm.com, gsi.ext.gm.com.