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DTC codes / P09xx · Transmission / P0953

P0953Auto Shift Manual Control Circuit High

P0953 means the transmission control module (TCM) has detected an abnormally high voltage on the electrical circuit for the auto shift manual control, which is the driver-operated selector or shift request input for an automated manual transmission. The TCM expects a specific voltage range on that signal circuit, and a reading above the calibrated threshold triggers this code.

SystemPowertrain
Code typeGeneric (all makes)
SeverityHigh
Fix difficultyProfessional
AreaTransmission

Symptoms you may notice

  • The transmission may refuse to engage drive or reverse, leaving the vehicle stuck in neutral.
  • The gear position indicator may flash, show a dash, or display an incorrect gear.
  • The vehicle may enter limp mode with reduced power and limited gear selection.
  • Shift requests from the selector may be ignored or delayed, making the car undrivable.
  • Often no symptoms besides the warning light if the fault is intermittent.
  • A warning chime or message may appear on the instrument cluster.

Common causes, most likely first

  1. A short to voltage on the signal circuit, often from chafed wiring rubbing against a grounded or powered component.
  2. A faulty auto shift manual control selector or shift request switch that outputs a high voltage.
  3. Corroded, loose, or pushed-back pins at the selector connector or TCM connector.
  4. Water intrusion into the selector assembly or its connector, causing a high-resistance or shorted path.
  5. A failed TCM driver or internal pull-up resistor that misreads the circuit voltage.
  6. A poor ground for the selector or TCM, which can skew the signal voltage high.
  7. Aftermarket accessories or wiring repairs that backfeed voltage onto the signal circuit.

How to diagnose and fix it

  1. Scan all modules and record freeze-frame data to confirm P0953 is current and not a history code from a previous repair.
  2. Inspect the selector connector and TCM connector for corrosion, loose pins, and water intrusion, then clean and reseat as needed.
  3. Measure the signal circuit voltage at the selector with the key on and compare it to the manufacturer's expected range.
  4. Disconnect the selector and check for voltage on the signal circuit with the key on; voltage present with the selector unplugged indicates a short to voltage in the harness.
  5. Perform a wiggle test on the harness while watching live data for the shift request voltage to catch intermittent shorts.
  6. If the harness and connectors are good, substitute a known-good selector or use a scan tool to command shift requests and verify TCM response.
  7. Repair or replace the faulty harness, selector, or TCM as indicated, then clear codes and verify the circuit voltage returns to normal.

What a high-voltage shift circuit really means

  • A short to voltage on the signal circuit is more common than a failed selector, so inspect the harness routing near heat sources and moving components before replacing parts.
  • This code can set from a poor ground at the selector or TCM, which raises the signal voltage without any short, so never skip ground voltage-drop testing.
  • An intermittent P0953 that only appears in wet weather often points to water intrusion in the selector connector or a chafed wire behind the dash.
  • Aftermarket remote starters or alarm wiring tapped into the shift circuit can backfeed voltage and set this code, so check for non-factory wiring first.
  • Do not assume the TCM is bad; a failed TCM is rare, and most P0953 repairs trace back to the harness or selector connector.

Can I keep driving with P0953?

Do not drive the vehicle if it will not engage a gear or is stuck in limp mode, because the transmission may not respond to shift requests and the car can become unsafe in traffic. If the vehicle still moves and the light is the only symptom, drive only to a repair shop and avoid heavy traffic or highway speeds.

Tools that help

Tools we recommend are in the Auto Veteran shop on Amazon. As an Amazon Associate we earn from qualifying purchases.

Guidance is general and written for all OBD-II vehicles. Exact tests and values vary by model, so confirm the fault before replacing parts.

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