Powertrain, generic · Transmission

P0827 Up and Down Shift Switch Circuit Low

Check engine lightOn
EmissionsNot relevant
Drive cycleNot required
Limp modePossible

Many selectors read tap-up and tap-down over one shared wire with voltage steps or a resistor network; P0826–P0828 cover this shared circuit, P0815/P0816 the single directions. P0827 means the shared circuit voltage is too low – a short to ground, depending on the design an open on a pulled-up input, or a switch held closed. The only documented user is Ram's 2025 heavy-duty truck with the 6.7 Cummins and eight-speed TorqueFlite HD: a 2026 bulletin lists P0827 with P0826 and P085F and the MIL; the display shows N although P is engaged, the engine cannot be switched off and limp mode is possible. The fix was new transmission software. Saab reports the same state under P0826 (below 0.2 V for 30 s), GM under P0826.

Likely causes

Signal wire shorted to ground
Tap switch held closed or selector assembly faulty
Transmission software (Ram 2025)
Control module faulty

Symptoms

  • Tap or manual shifting not working
  • MIL (Ram)
  • N shown although in P, engine cannot be switched off (Ram)

Repair estimate

DifficultyMediumWorkshop job
Parts and labour€0–600
Time0.5–2.5 h

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

Parts involved

tap shift switchgear selectorswitch wiringtransmission control module

Related codes

P0826P0828P085FP0815P0816

References: static.nhtsa.gov, saabwisonline.com, law.cornell.edu.