Powertrain, generic · Transmission
P071C Transmission Mode Switch A Circuit High
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. P071C means the signal of mode switch A is above its upper limit – typically an open circuit pulled up inside the module, or a short to positive. The mode then cannot be selected. The opposite is P071B.
Likely causes
Wire or connector to the button open
Button open internally
Signal wire shorted to positive
Symptoms
- Mode A 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.