Code
P0957
Generic
P — Powertrain
Auto Shift Manual Mode Circuit Low
AI status
Completed
Completed
100%
Causes
- Damaged or shorted wiring in the manual mode/auto shift switch circuit
- Poor or corroded connector(s) at the switch or PCM/TCM
- Faulty manual mode/auto shift switch (gear selector or steering paddle switch)
- Blown fuse or poor power/ground feeding the circuit
- Short to ground in the signal wire
- Faulty PCM/TCM or internal input driver (less common)
Symptoms
- Check Engine/Transmission MIL illuminated
- Inability to engage or hold manual shift mode (won't enter manual or reverts to automatic)
- Transmission stuck in limp/backup mode in some vehicles
- Faults logged for transmission shift inputs
- Intermittent or permanent loss of manual shift function
What to check
- Read and record freeze frame and live data with a capable scan tool; confirm P0957 is current/active
- Visually inspect wiring and connectors at the shifter, steering wheel paddle (if applicable), and PCM/TCM
- Check fuses and power/ground circuits related to transmission control and shift selector
- Try the manual shift operation while monitoring the signal parameter with a scan tool (key on, engine off for voltage checks)
- Wiggle harnesses and connectors while watching live data for intermittent changes
Signal parameters
- Expected: digital/switch-type input. When circuit is not active typical signal ~5 V (or VIN reference) or open depending on design — consult vehicle wiring diagram
- Low/failed condition: signal near 0–0.5 V or effectively grounded when it should be high
- Switch closed continuity: near 0 Ω (or low resistance) between switch contacts when actuated; open/infinite when not actuated (depends on switch type)
- Resistance to ground on signal wire should be high (no short).
Diagnostic algorithm
- Obtain full trouble code data, freeze frame and current live data from scan tool; confirm P0957 is present and note status (pending/permanent)
- Inspect fuses and relays for the transmission/shifter circuits; replace any blown fuses and retest
- Perform a visual inspection of the shifter/switch assembly, wiring harness and connectors for damage, corrosion, or water ingress; repair as needed
- Backprobe the manual-mode signal wire at the switch with key ON (engine off) and measure voltage: compare to expected reference (usually ~5 V or key supply). Record readings with switch in both positions
- If the signal is low at the switch connector but normal at the PCM/TCM, repair/replace the switch or connector. If signal is low at the module, inspect wiring between switch and module for shorts to ground or open circuits
- Check continuity/resistance of the signal wire to the PCM/TCM; repair any opens or shorted sections. Perform a wiggle test while observing live data to find intermittent faults
- If wiring and switch verify good, perform module input driver tests per manufacturer service info; consider module replacement only after excluding harness and switch faults
- Clear codes, perform functional test of manual shift mode and road test to confirm repair; re-scan for any returning codes
Likely causes
- Connector pins pushed out, corroded or bent at the mode switch or module
- Chafed wiring rubbing to chassis ground causing low/grounded signal
- Water intrusion or contamination in shift selector module/switch
- Failed switch contacts (stuck open or low-resistance path to ground)
- Fuse for transmission control or shift circuitry open
Fault status
Status
P0957 — Auto Shift Manual Mode Circuit Low: signal below expected range (possible short to ground or open/failed switch).
Repair difficulty: Medium
Diagnostic time: 0.5-2.0 hours
Repair manuals
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