Auto Shift Manual Control Circuit High
The Powertrain Control Module (PCM) or Transmission Control Module (TCM) has detected an abnormally high electrical voltage in the auto shift manual control circuit. This circuit monitors the driver's inputs for manual gear selection, and a high voltage reading typically indicates a short to power or an internal switch failure.
While the vehicle can usually still be driven in standard automatic mode, this code disables manual shifting features and may trigger a transmission limp mode. It should be diagnosed soon to restore full transmission functionality.
Common symptoms
- Illuminated Check Engine Light
- Inability to use the manual shift (up/down) feature
- Transmission may default to a fail-safe or limp mode
- Harsh or erratic automatic shifting
- Gear indicator on the dashboard may flash or display incorrectly
Likely causes
- Liquid spilled on the center console or shifter assembly
- Faulty auto shift manual control switch
- Short to voltage in the auto shift manual control circuit wiring
- Corroded, loose, or damaged electrical connectors at the shifter assembly
- Faulty Transmission Control Module (TCM) or PCM (rare)
What to check before replacing parts
Inspect the center console and shifter assembly for signs of spilled liquids or physical damage.
Look for: Sticky residue, corrosion, or moisture around the manual shift switches that could cause an electrical short.
Check the wiring harness and connectors leading to the auto shift manual switch.
Look for: Frayed wires, melted insulation, or corroded pins that could cause a short to voltage or an open circuit.
Use a scan tool to monitor the auto shift manual switch PID data while toggling the shifter.
Look for: The scan tool should show the switch state changing (e.g., upshift/downshift); if it remains stuck on a high voltage state, the switch or circuit is faulty.
Test the auto shift manual control circuit for a short to voltage using a digital multimeter.
Look for: With the switch disconnected, check for unexpected battery voltage on the signal wire, which confirms a short to power in the wiring harness.
Test the auto shift manual switch continuity with a multimeter.
Look for: The switch should show continuity only when pressed or engaged; if it shows continuity at rest, the switch itself has failed internally.
This page explains the generic P0953 definition and is general reference information, not a diagnosis for your specific vehicle. Actual causes, severity, and repairs vary by make, model, engine, and mileage — always confirm with a scan tool and a qualified technician before replacing parts.
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