Powertrain, generic · Transmission
P071D Transmission Mode Switch B Circuit
Check engine lightUsually off
EmissionsNot relevant
Drive cycleNot required
Limp modeNo
A transmission mode switch selects an alternative shift schedule such as sport, winter or tow/haul; J2012 does not define which button is A or B. No manufacturer document available to us uses P071A–P071F: GM monitors its analog drive mode switch under its own codes (low below 21–29 % of 5 V, high from 94 %, 200 of 250 samples, two trips), which shows how such buttons are read as coded voltages. P071D is the general circuit fault of a second mode switch B, for example a separate winter and sport or tow/haul button. The second mode is then unavailable. Low and high are P071E/P071F; switch A has P071A–P071C.
Likely causes
Mode switch B faulty (selector lever or console)
Wiring or connector in the console damaged (spilled drinks, chafing)
Resistor coding drifted (analog buttons)
Control module faulty
Symptoms
- Mode B cannot be selected or stays active
- Mode indicator missing or flashing
- Transmission stays on the normal shift schedule
Repair estimate
DifficultyEasyDIY possible
Parts and labour€30–300
Time0.3–1.5 h
Typical range across vehicles; the real cost depends on what the testing finds.
Parts involved
transmission mode switchswitch wiringtransmission control module
Related codes
References: law.cornell.edu, gsi.ext.gm.com.