Powertrain, generic · Vehicle speed, idle control and auxiliary inputs

P05D1 Driver Mode Select Switch A Circuit Low

Check engine lightOn
EmissionsRelevant
Drive cycleRequired
Limp modeNo

The driver mode select switch (tour, sport, eco, snow, off-road, towing) changes engine and transmission maps such as shift points, pedal map and cylinder deactivation, so CARB requires it to be monitored as an input. GM reads switch A as an eight-position resistor ladder in the body module and sets P05D1–P05D3 in its 2025 tables when a condition is present for 4 s within 5 s, type B with warning lamp after two trips. A fault blocks mode selection; the vehicle stays in its basic mode. P05D1 means the signal is below the lowest valid window: GM petrol body modules below 1.327 V, diesel below 0.528 V. Typical are a signal shorted to ground or a shorted switch.

Likely causes

Signal line to the body module shorted to ground (chafing in the console)
Switch shorted internally (moisture, spilled drink)
Connector at the switch damaged
Body module input

Symptoms

  • Drive mode cannot be changed, vehicle stays in normal mode
  • Mode display missing or jumping back
  • Check engine light (GM after two trips)

Repair estimate

DifficultyMediumDIY possible
Parts and labour€30–350
Time0.5–1.5 h

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

Parts involved

drive mode switchswitch wiringbody control module

Related codes

P05D0P05D2P05D3P05D5

References: gsi.ext.gm.com, gsi.ext.gm.com, law.cornell.edu.