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

P05D6 Driver Mode Select Switch B Circuit High

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. No manufacturer document available to us uses codes for switch B (a second mode switch or second signal line); its monitoring is assumed to match switch A. P05D6 means its signal is above the valid range – with a pull-up usually an open circuit, otherwise a short to positive, like P05D2 for switch A.

Likely causes

Connector off or wire open
Switch B faulty
Short to positive

Symptoms

  • Mode selection via switch B inoperative
  • Check engine light possible
  • Vehicle stays in its basic mode

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

P05D4P05D5P05D7P05D2

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